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• FFMPEG My stitched frames colors looks very different from my original video, causing my video to not be able to stitch it back properly

  26 mai 2024, par Wer Wer

  I am trying to extract some frames off my video to do some form of steganography. I accidentally used a 120fps video, causing the files to be too big when i extract every single frame. To fix this, I decided to calculate how many frames is needed to hide the bits (LSB replacement for every 8 bit) and then extract only certain amount of frames. This means

  


  

  1. if i only need 1 frame, ill extract frame0.png

  


  2. ill remove frame0 from the original video

  


  3. encode my data into frame0.png

  


  4. stitch frame0 back into ffv1 video

  


  5. concatenate frame0 video to the rest of the video, frame0 video in front.

  


  


  I can do extraction and remove frame0 from the video. However, when looking at frame0.mkv and the original.mkv, i realised the colors seemed to be different.
Frame0.mkv
original.mkv

  


  This causes a glitch during the stitching of videos together, where the end of the video has some corrupted pixels. Not only that, it stops the video at where frame0 ends. I think those corrupted pixels were supposed to be original.mkv pixels, but they did not concatenate properly.
results.mkv

  


  I use an ffmpeg sub command to extract frames and stitch them

  


      def split_into_frames(self, ffv1_video, hidden_text_length):
        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        ffv1_video_path = os.path.join(self.here, ffv1_video)
        ffv1_video = cv2.VideoCapture(ffv1_video_path)

        currentframe = 0
        total_frame_bits = 0
        frames_to_remove = []

        while True:
            ret, frame = ffv1_video.read()
            if ret:
                name = os.path.join(self.here, "data", f"frame{currentframe}.png")
                print("Creating..." + name)
                cv2.imwrite(name, frame)

                current_frame_path = os.path.join(
                    self.here, "data", f"frame{currentframe}.png"
                )

                if os.path.exists(current_frame_path):
                    binary_data = self.read_frame_binary(current_frame_path)

                if (total_frame_bits // 8) >= hidden_text_length:
                    print("Complete")
                    break
                total_frame_bits += len(binary_data)
                frames_to_remove.append(currentframe)
                currentframe += 1
            else:
                print("Complete")
                break

        ffv1_video.release()

        # Remove the extracted frames from the original video
        self.remove_frames_from_video(ffv1_video_path, frames_to_remove)



  


  This code splits the video into the required number of frames. It checks if the total amount of frame bits is enough to encode the hidden text

  


  def remove_frames_from_video(self, input_video, frames_to_remove):
    if not input_video.endswith(".mkv"):
        input_video += ".mkv"

    input_video_path = os.path.join(self.here, input_video)

    # Create a filter string to exclude specific frames
    filter_str = (
        "select='not("
        + "+".join([f"eq(n\,{frame})" for frame in frames_to_remove])
        + ")',setpts=N/FRAME_RATE/TB"
    )

    # Temporary output video path
    output_video_path = os.path.join(self.here, "temp_output.mkv")

    command = [
        "ffmpeg",
        "-y",
        "-i",
        input_video_path,
        "-vf",
        filter_str,
        "-c:v",
        "ffv1",
        "-level",
        "3",
        "-coder",
        "1",
        "-context",
        "1",
        "-g",
        "1",
        "-slices",
        "4",
        "-slicecrc",
        "1",
        "-an",  # Remove audio
        output_video_path,
    ]

    try:
        subprocess.run(command, check=True)
        print(f"Frames removed. Temporary video created at {output_video_path}")

        # Replace the original video with the new video
        os.replace(output_video_path, input_video_path)
        print(f"Original video replaced with updated video at {input_video_path}")

        # Re-add the trimmed audio to the new video
        self.trim_audio_and_add_to_video(input_video_path, frames_to_remove)
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")
        if os.path.exists(output_video_path):
            os.remove(output_video_path)

def trim_audio_and_add_to_video(self, video_path, frames_to_remove):
    # Calculate the new duration based on the remaining frames
    fps = 60  # Assuming the framerate is 60 fps
    total_frames_removed = len(frames_to_remove)
    original_duration = self.get_video_duration(video_path)
    new_duration = original_duration - (total_frames_removed / fps)

    # Extract and trim the audio
    audio_path = os.path.join(self.here, "trimmed_audio.aac")
    command_extract_trim = [
        "ffmpeg",
        "-y",
        "-i",
        video_path,
        "-t",
        str(new_duration),
        "-q:a",
        "0",
        "-map",
        "a",
        audio_path,
    ]
    try:
        subprocess.run(command_extract_trim, check=True)
        print(f"Audio successfully trimmed and extracted to {audio_path}")

        # Add the trimmed audio back to the video
        final_video_path = video_path.replace(".mkv", "_final.mkv")
        command_add_audio = [
            "ffmpeg",
            "-y",
            "-i",
            video_path,
            "-i",
            audio_path,
            "-c:v",
            "copy",
            "-c:a",
            "aac",
            "-strict",
            "experimental",
            final_video_path,
        ]
        subprocess.run(command_add_audio, check=True)
        print(f"Final video with trimmed audio created at {final_video_path}")

        # Replace the original video with the final video
        os.replace(final_video_path, video_path)
        print(f"Original video replaced with final video at {video_path}")
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")

def get_video_duration(self, video_path):
    command = [
        "ffprobe",
        "-v",
        "error",
        "-show_entries",
        "format=duration",
        "-of",
        "default=noprint_wrappers=1:nokey=1",
        video_path,
    ]
    try:
        result = subprocess.run(
            command, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
        )
        duration = float(result.stdout.decode().strip())
        return duration
    except subprocess.CalledProcessError as e:
        print(f"An error occurred while getting video duration: {e}")
        return 0.0


  


  here ill remove all the frames that has been extracted from the video

  


  def stitch_frames_to_video(self, ffv1_video, framerate=60):
    # this command is another ffmpeg subcommand.
    # it takes every single frame from data1 directory and stitch it back into a ffv1 video
    if not ffv1_video.endswith(".mkv"):
        ffv1_video += ".mkv"

    output_video_path = os.path.join(self.here, ffv1_video)

    command = [
        "ffmpeg",
        "-y",
        "-framerate",
        str(framerate),
        "-i",
        os.path.join(self.frames_directory, "frame%d.png"),
        "-c:v",
        "ffv1",
        "-level",
        "3",
        "-coder",
        "1",
        "-context",
        "1",
        "-g",
        "1",
        "-slices",
        "4",
        "-slicecrc",
        "1",
        output_video_path,
    ]

    try:
        subprocess.run(command, check=True)
        print(f"Video successfully created at {output_video_path}")
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")


  


  after encoding the frames, ill try to stitch the frames back into ffv1 video

  


  def concatenate_videos(self, video1_path, video2_path, output_path):
    if not video1_path.endswith(".mkv"):
        video1_path += ".mkv"
    if not video2_path.endswith(".mkv"):
        video2_path += ".mkv"
    if not output_path.endswith(".mkv"):
        output_path += ".mkv"

    video1_path = os.path.join(self.here, video1_path)
    video2_path = os.path.join(self.here, video2_path)
    output_video_path = os.path.join(self.here, output_path)

    # Create a text file with the paths of the videos to concatenate
    concat_list_path = os.path.join(self.here, "concat_list.txt")
    with open(concat_list_path, "w") as f:
        f.write(f"file '{video1_path}'\n")
        f.write(f"file '{video2_path}'\n")

    command = [
        "ffmpeg",
        "-y",
        "-f",
        "concat",
        "-safe",
        "0",
        "-i",
        concat_list_path,
        "-c",
        "copy",
        output_video_path,
    ]

    try:
        subprocess.run(command, check=True)
        print(f"Videos successfully concatenated into {output_video_path}")
        os.remove(concat_list_path)  # Clean up the temporary file
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")


  


  now i try to concatenate the frames video with the original video, but it is corrupting as the colors are different.

  


  this code does the other processing by removing all the extracted frames from the video, as well as trimming the audio (but i think ill be removing the audio trimming as i realised it is not needed at all)

  


  I think its because .png frames will lose colors when they get extracted out. The only work around I know is to extract every single frame. But this causes the program to run too long as for a 12 second video, I will extract 700++ frames. Is there a way to fix this ?

  


  my full code

  


  import json
import os
import shutil
import magic
import ffmpeg
import cv2
import numpy as np
import subprocess
from PIL import Image
import glob


import json
import os
import shutil
import magic
import ffmpeg
import cv2
import numpy as np
import subprocess
from PIL import Image
import glob


class FFV1Steganography:
    def __init__(self):
        self.here = os.path.dirname(os.path.abspath(__file__))

        # Create a folder to save the frames
        self.frames_directory = os.path.join(self.here, "data")
        try:
            if not os.path.exists(self.frames_directory):
                os.makedirs(self.frames_directory)
        except OSError:
            print("Error: Creating directory of data")

    def read_hidden_text(self, filename):
        file_path_txt = os.path.join(self.here, filename)
        # Read the content of the file in binary mode
        with open(file_path_txt, "rb") as f:
            hidden_text_content = f.read()
        return hidden_text_content

    def calculate_length_of_hidden_text(self, filename):
        hidden_text_content = self.read_hidden_text(filename)
        # Convert each byte to its binary representation and join them
        return len("".join(format(byte, "08b") for byte in hidden_text_content))

    def find_raw_video_file(self, filename):
        file_extensions = [".mp4", ".mkv", ".avi"]
        for ext in file_extensions:
            file_path = os.path.join(self.here, filename + ext)
            if os.path.isfile(file_path):
                return file_path
        return None

    def convert_video(self, input_file, ffv1_video):
        # this function is the same as running this command line
        # ffmpeg -i video.mp4 -t 12 -c:v ffv1 -level 3 -coder 1 -context 1 -g 1 -slices 4 -slicecrc 1 -c:a copy output.mkv

        # in order to run any ffmpeg subprocess, you have to have ffmpeg installed into the computer.
        # https://ffmpeg.org/download.html

        # WARNING:
        # the ffmpeg you should download is not the same as the ffmpeg library for python.
        # you need to download the exe from the link above, then add ffmpeg bin directory to system variables
        output_file = os.path.join(self.here, ffv1_video)

        if not output_file.endswith(".mkv"):
            output_file += ".mkv"

        command = [
            "ffmpeg",
            "-y",
            "-i",
            input_file,
            "-t",
            "12",
            "-c:v",
            "ffv1",
            "-level",
            "3",
            "-coder",
            "1",
            "-context",
            "1",
            "-g",
            "1",
            "-slices",
            "4",
            "-slicecrc",
            "1",
            "-c:a",
            "copy",
            output_file,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Conversion successful: {output_file}")
            return output_file
        except subprocess.CalledProcessError as e:
            print(f"Error during conversion: {e}")

    def extract_audio(self, ffv1_video, audio_path):
        # Ensure the audio output file has the correct extension
        if not audio_path.endswith(".aac"):
            audio_path += ".aac"

        # Full path to the extracted audio file
        extracted_audio = os.path.join(self.here, audio_path)

        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        command = [
            "ffmpeg",
            "-i",
            ffv1_video,
            "-q:a",
            "0",
            "-map",
            "a",
            extracted_audio,
        ]
        try:
            result = subprocess.run(
                command, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
            )
            print(f"Audio successfully extracted to {extracted_audio}")
            print(result.stdout.decode())
            print(result.stderr.decode())
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")
            print(e.stdout.decode())
            print(e.stderr.decode())

    def read_frame_binary(self, frame_path):
        # Open the image and convert to binary
        with open(frame_path, "rb") as f:
            binary_content = f.read()
            binary_string = "".join(format(byte, "08b") for byte in binary_content)
        return binary_string

    def remove_frames_from_video(self, input_video, frames_to_remove):
        if not input_video.endswith(".mkv"):
            input_video += ".mkv"

        input_video_path = os.path.join(self.here, input_video)

        # Create a filter string to exclude specific frames
        filter_str = (
            "select='not("
            + "+".join([f"eq(n\,{frame})" for frame in frames_to_remove])
            + ")',setpts=N/FRAME_RATE/TB"
        )

        # Temporary output video path
        output_video_path = os.path.join(self.here, "temp_output.mkv")

        command = [
            "ffmpeg",
            "-y",
            "-i",
            input_video_path,
            "-vf",
            filter_str,
            "-c:v",
            "ffv1",
            "-level",
            "3",
            "-coder",
            "1",
            "-context",
            "1",
            "-g",
            "1",
            "-slices",
            "4",
            "-slicecrc",
            "1",
            "-an",  # Remove audio
            output_video_path,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Frames removed. Temporary video created at {output_video_path}")

            # Replace the original video with the new video
            os.replace(output_video_path, input_video_path)
            print(f"Original video replaced with updated video at {input_video_path}")

            # Re-add the trimmed audio to the new video
            self.trim_audio_and_add_to_video(input_video_path, frames_to_remove)
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")
            if os.path.exists(output_video_path):
                os.remove(output_video_path)

    def trim_audio_and_add_to_video(self, video_path, frames_to_remove):
        # Calculate the new duration based on the remaining frames
        fps = 60  # Assuming the framerate is 60 fps
        total_frames_removed = len(frames_to_remove)
        original_duration = self.get_video_duration(video_path)
        new_duration = original_duration - (total_frames_removed / fps)

        # Extract and trim the audio
        audio_path = os.path.join(self.here, "trimmed_audio.aac")
        command_extract_trim = [
            "ffmpeg",
            "-y",
            "-i",
            video_path,
            "-t",
            str(new_duration),
            "-q:a",
            "0",
            "-map",
            "a",
            audio_path,
        ]
        try:
            subprocess.run(command_extract_trim, check=True)
            print(f"Audio successfully trimmed and extracted to {audio_path}")

            # Add the trimmed audio back to the video
            final_video_path = video_path.replace(".mkv", "_final.mkv")
            command_add_audio = [
                "ffmpeg",
                "-y",
                "-i",
                video_path,
                "-i",
                audio_path,
                "-c:v",
                "copy",
                "-c:a",
                "aac",
                "-strict",
                "experimental",
                final_video_path,
            ]
            subprocess.run(command_add_audio, check=True)
            print(f"Final video with trimmed audio created at {final_video_path}")

            # Replace the original video with the final video
            os.replace(final_video_path, video_path)
            print(f"Original video replaced with final video at {video_path}")
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def get_video_duration(self, video_path):
        command = [
            "ffprobe",
            "-v",
            "error",
            "-show_entries",
            "format=duration",
            "-of",
            "default=noprint_wrappers=1:nokey=1",
            video_path,
        ]
        try:
            result = subprocess.run(
                command, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
            )
            duration = float(result.stdout.decode().strip())
            return duration
        except subprocess.CalledProcessError as e:
            print(f"An error occurred while getting video duration: {e}")
            return 0.0

    def split_into_frames(self, ffv1_video, hidden_text_length):
        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        ffv1_video_path = os.path.join(self.here, ffv1_video)
        ffv1_video = cv2.VideoCapture(ffv1_video_path)

        currentframe = 0
        total_frame_bits = 0
        frames_to_remove = []

        while True:
            ret, frame = ffv1_video.read()
            if ret:
                name = os.path.join(self.here, "data", f"frame{currentframe}.png")
                print("Creating..." + name)
                cv2.imwrite(name, frame)

                current_frame_path = os.path.join(
                    self.here, "data", f"frame{currentframe}.png"
                )

                if os.path.exists(current_frame_path):
                    binary_data = self.read_frame_binary(current_frame_path)

                if (total_frame_bits // 8) >= hidden_text_length:
                    print("Complete")
                    break
                total_frame_bits += len(binary_data)
                frames_to_remove.append(currentframe)
                currentframe += 1
            else:
                print("Complete")
                break

        ffv1_video.release()

        # Remove the extracted frames from the original video
        self.remove_frames_from_video(ffv1_video_path, frames_to_remove)

    def stitch_frames_to_video(self, ffv1_video, framerate=60):
        # this command is another ffmpeg subcommand.
        # it takes every single frame from data1 directory and stitch it back into a ffv1 video
        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        output_video_path = os.path.join(self.here, ffv1_video)

        command = [
            "ffmpeg",
            "-y",
            "-framerate",
            str(framerate),
            "-i",
            os.path.join(self.frames_directory, "frame%d.png"),
            "-c:v",
            "ffv1",
            "-level",
            "3",
            "-coder",
            "1",
            "-context",
            "1",
            "-g",
            "1",
            "-slices",
            "4",
            "-slicecrc",
            "1",
            output_video_path,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Video successfully created at {output_video_path}")
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def add_audio_to_video(self, encoded_video, audio_path, final_video):
        # the audio will be lost during splitting and restitching.
        # that is why previously we separated the audio from video and saved it as aac.
        # now, we can put the audio back into the video, again using ffmpeg subcommand.

        if not encoded_video.endswith(".mkv"):
            encoded_video += ".mkv"

        if not final_video.endswith(".mkv"):
            final_video += ".mkv"

        if not audio_path.endswith(".aac"):
            audio_path += ".aac"

        final_output_path = os.path.join(self.here, final_video)

        command = [
            "ffmpeg",
            "-y",
            "-i",
            os.path.join(self.here, encoded_video),
            "-i",
            os.path.join(self.here, audio_path),
            "-c:v",
            "copy",
            "-c:a",
            "aac",
            "-strict",
            "experimental",
            final_output_path,
        ]
        try:
            subprocess.run(command, check=True)
            print(f"Final video with audio created at {final_output_path}")
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def concatenate_videos(self, video1_path, video2_path, output_path):
        if not video1_path.endswith(".mkv"):
            video1_path += ".mkv"
        if not video2_path.endswith(".mkv"):
            video2_path += ".mkv"
        if not output_path.endswith(".mkv"):
            output_path += ".mkv"

        video1_path = os.path.join(self.here, video1_path)
        video2_path = os.path.join(self.here, video2_path)
        output_video_path = os.path.join(self.here, output_path)

        # Create a text file with the paths of the videos to concatenate
        concat_list_path = os.path.join(self.here, "concat_list.txt")
        with open(concat_list_path, "w") as f:
            f.write(f"file '{video1_path}'\n")
            f.write(f"file '{video2_path}'\n")

        command = [
            "ffmpeg",
            "-y",
            "-f",
            "concat",
            "-safe",
            "0",
            "-i",
            concat_list_path,
            "-c",
            "copy",
            output_video_path,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Videos successfully concatenated into {output_video_path}")
            os.remove(concat_list_path)  # Clean up the temporary file
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def cleanup(self, files_to_delete):
        # Delete specified files
        for file in files_to_delete:
            file_path = os.path.join(self.here, file)
            if os.path.exists(file_path):
                os.remove(file_path)
                print(f"Deleted file: {file_path}")
            else:
                print(f"File not found: {file_path}")

        # Delete the frames directory and its contents
        if os.path.exists(self.frames_directory):
            shutil.rmtree(self.frames_directory)
            print(f"Deleted directory and its contents: {self.frames_directory}")
        else:
            print(f"Directory not found: {self.frames_directory}")


if __name__ == "__main__":
    stego = FFV1Steganography()

    # original video (mp4,mkv,avi)
    original_video = "video"
    # converted ffv1 video
    ffv1_video = "output"
    # extracted audio
    extracted_audio = "audio"
    # encoded video without sound
    encoded_video = "encoded"
    # final result video, encoded, with sound
    final_video = "result"

    # region --hidden text processing --
    hidden_text = stego.read_hidden_text("hiddentext.txt")
    hidden_text_length = stego.calculate_length_of_hidden_text("hiddentext.txt")
    # endregion

    # region -- raw video locating --
    raw_video_file = stego.find_raw_video_file(original_video)
    if raw_video_file:
        print(f"Found video file: {raw_video_file}")
    else:
        print("video.mp4 not found.")
    # endregion

    # region -- video processing INPUT--
    # converted_video_file = stego.convert_video(raw_video_file, ffv1_video)
    # if converted_video_file and os.path.exists(converted_video_file):
    #     stego.extract_audio(converted_video_file, extracted_audio)
    # else:
    #     print(f"Conversion failed: {converted_video_file} not found.")

    # stego.split_into_frames(ffv1_video, hidden_text_length * 50000)
    # endregion

    # region -- video processing RESULT --
    # stego.stitch_frames_to_video(encoded_video)
    stego.concatenate_videos(encoded_video, ffv1_video, final_video)
    # stego.add_audio_to_video(final_video, extracted_audio, final_video)
    # endregion

    # region -- cleanup --
    files_to_delete = [
        extracted_audio + ".aac",
        encoded_video + ".mkv",
        ffv1_video + ".mkv",
    ]

 stego.cleanup(files_to_delete)
    # endregion







  


• My stitched frames colors looks very different from my original video, causing my video to not be able to stitch it back properly [closed]

  27 mai 2024, par Wer Wer

  I am trying to extract some frames off my video to do some form of steganography. I accidentally used a 120fps video, causing the files to be too big when i extract every single frame. To fix this, I decided to calculate how many frames is needed to hide the bits (LSB replacement for every 8 bit) and then extract only certain amount of frames. This means

  


  

  1. if i only need 1 frame, ill extract frame0.png

  


  2. ill remove frame0 from the original video

  


  3. encode my data into frame0.png

  


  4. stitch frame0 back into ffv1 video

  


  5. concatenate frame0 video to the rest of the video, frame0 video in front.

  


  


  I can do extraction and remove frame0 from the video. However, when looking at frame0.mkv and the original.mkv, i realised the colors seemed to be different.
Frame0.mkv
original.mkv

  


  This causes a glitch during the stitching of videos together, where the end of the video has some corrupted pixels. Not only that, it stops the video at where frame0 ends. I think those corrupted pixels were supposed to be original.mkv pixels, but they did not concatenate properly.
results.mkv

  


  I use an ffmpeg sub command to extract frames and stitch them

  


      def split_into_frames(self, ffv1_video, hidden_text_length):
        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        ffv1_video_path = os.path.join(self.here, ffv1_video)
        ffv1_video = cv2.VideoCapture(ffv1_video_path)

        currentframe = 0
        total_frame_bits = 0
        frames_to_remove = []

        while True:
            ret, frame = ffv1_video.read()
            if ret:
                name = os.path.join(self.here, "data", f"frame{currentframe}.png")
                print("Creating..." + name)
                cv2.imwrite(name, frame)

                current_frame_path = os.path.join(
                    self.here, "data", f"frame{currentframe}.png"
                )

                if os.path.exists(current_frame_path):
                    binary_data = self.read_frame_binary(current_frame_path)

                if (total_frame_bits // 8) >= hidden_text_length:
                    print("Complete")
                    break
                total_frame_bits += len(binary_data)
                frames_to_remove.append(currentframe)
                currentframe += 1
            else:
                print("Complete")
                break

        ffv1_video.release()

        # Remove the extracted frames from the original video
        self.remove_frames_from_video(ffv1_video_path, frames_to_remove)



  


  This code splits the video into the required number of frames. It checks if the total amount of frame bits is enough to encode the hidden text

  


  def remove_frames_from_video(self, input_video, frames_to_remove):
    if not input_video.endswith(".mkv"):
        input_video += ".mkv"

    input_video_path = os.path.join(self.here, input_video)

    # Create a filter string to exclude specific frames
    filter_str = (
        "select='not("
        + "+".join([f"eq(n\,{frame})" for frame in frames_to_remove])
        + ")',setpts=N/FRAME_RATE/TB"
    )

    # Temporary output video path
    output_video_path = os.path.join(self.here, "temp_output.mkv")

    command = [
        "ffmpeg",
        "-y",
        "-i",
        input_video_path,
        "-vf",
        filter_str,
        "-c:v",
        "ffv1",
        "-level",
        "3",
        "-coder",
        "1",
        "-context",
        "1",
        "-g",
        "1",
        "-slices",
        "4",
        "-slicecrc",
        "1",
        "-an",  # Remove audio
        output_video_path,
    ]

    try:
        subprocess.run(command, check=True)
        print(f"Frames removed. Temporary video created at {output_video_path}")

        # Replace the original video with the new video
        os.replace(output_video_path, input_video_path)
        print(f"Original video replaced with updated video at {input_video_path}")

        # Re-add the trimmed audio to the new video
        self.trim_audio_and_add_to_video(input_video_path, frames_to_remove)
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")
        if os.path.exists(output_video_path):
            os.remove(output_video_path)

def trim_audio_and_add_to_video(self, video_path, frames_to_remove):
    # Calculate the new duration based on the remaining frames
    fps = 60  # Assuming the framerate is 60 fps
    total_frames_removed = len(frames_to_remove)
    original_duration = self.get_video_duration(video_path)
    new_duration = original_duration - (total_frames_removed / fps)

    # Extract and trim the audio
    audio_path = os.path.join(self.here, "trimmed_audio.aac")
    command_extract_trim = [
        "ffmpeg",
        "-y",
        "-i",
        video_path,
        "-t",
        str(new_duration),
        "-q:a",
        "0",
        "-map",
        "a",
        audio_path,
    ]
    try:
        subprocess.run(command_extract_trim, check=True)
        print(f"Audio successfully trimmed and extracted to {audio_path}")

        # Add the trimmed audio back to the video
        final_video_path = video_path.replace(".mkv", "_final.mkv")
        command_add_audio = [
            "ffmpeg",
            "-y",
            "-i",
            video_path,
            "-i",
            audio_path,
            "-c:v",
            "copy",
            "-c:a",
            "aac",
            "-strict",
            "experimental",
            final_video_path,
        ]
        subprocess.run(command_add_audio, check=True)
        print(f"Final video with trimmed audio created at {final_video_path}")

        # Replace the original video with the final video
        os.replace(final_video_path, video_path)
        print(f"Original video replaced with final video at {video_path}")
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")

def get_video_duration(self, video_path):
    command = [
        "ffprobe",
        "-v",
        "error",
        "-show_entries",
        "format=duration",
        "-of",
        "default=noprint_wrappers=1:nokey=1",
        video_path,
    ]
    try:
        result = subprocess.run(
            command, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
        )
        duration = float(result.stdout.decode().strip())
        return duration
    except subprocess.CalledProcessError as e:
        print(f"An error occurred while getting video duration: {e}")
        return 0.0


  


  here ill remove all the frames that has been extracted from the video

  


  def stitch_frames_to_video(self, ffv1_video, framerate=60):
    # this command is another ffmpeg subcommand.
    # it takes every single frame from data1 directory and stitch it back into a ffv1 video
    if not ffv1_video.endswith(".mkv"):
        ffv1_video += ".mkv"

    output_video_path = os.path.join(self.here, ffv1_video)

    command = [
        "ffmpeg",
        "-y",
        "-framerate",
        str(framerate),
        "-i",
        os.path.join(self.frames_directory, "frame%d.png"),
        "-c:v",
        "ffv1",
        "-level",
        "3",
        "-coder",
        "1",
        "-context",
        "1",
        "-g",
        "1",
        "-slices",
        "4",
        "-slicecrc",
        "1",
        output_video_path,
    ]

    try:
        subprocess.run(command, check=True)
        print(f"Video successfully created at {output_video_path}")
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")


  


  after encoding the frames, ill try to stitch the frames back into ffv1 video

  


  def concatenate_videos(self, video1_path, video2_path, output_path):
    if not video1_path.endswith(".mkv"):
        video1_path += ".mkv"
    if not video2_path.endswith(".mkv"):
        video2_path += ".mkv"
    if not output_path.endswith(".mkv"):
        output_path += ".mkv"

    video1_path = os.path.join(self.here, video1_path)
    video2_path = os.path.join(self.here, video2_path)
    output_video_path = os.path.join(self.here, output_path)

    # Create a text file with the paths of the videos to concatenate
    concat_list_path = os.path.join(self.here, "concat_list.txt")
    with open(concat_list_path, "w") as f:
        f.write(f"file '{video1_path}'\n")
        f.write(f"file '{video2_path}'\n")

    command = [
        "ffmpeg",
        "-y",
        "-f",
        "concat",
        "-safe",
        "0",
        "-i",
        concat_list_path,
        "-c",
        "copy",
        output_video_path,
    ]

    try:
        subprocess.run(command, check=True)
        print(f"Videos successfully concatenated into {output_video_path}")
        os.remove(concat_list_path)  # Clean up the temporary file
    except subprocess.CalledProcessError as e:
        print(f"An error occurred: {e}")


  


  now i try to concatenate the frames video with the original video, but it is corrupting as the colors are different.

  


  this code does the other processing by removing all the extracted frames from the video, as well as trimming the audio (but i think ill be removing the audio trimming as i realised it is not needed at all)

  


  I think its because .png frames will lose colors when they get extracted out. The only work around I know is to extract every single frame. But this causes the program to run too long as for a 12 second video, I will extract 700++ frames. Is there a way to fix this ?

  


  my full code

  


  import json
import os
import shutil
import magic
import ffmpeg
import cv2
import numpy as np
import subprocess
from PIL import Image
import glob


import json
import os
import shutil
import magic
import ffmpeg
import cv2
import numpy as np
import subprocess
from PIL import Image
import glob


class FFV1Steganography:
    def __init__(self):
        self.here = os.path.dirname(os.path.abspath(__file__))

        # Create a folder to save the frames
        self.frames_directory = os.path.join(self.here, "data")
        try:
            if not os.path.exists(self.frames_directory):
                os.makedirs(self.frames_directory)
        except OSError:
            print("Error: Creating directory of data")

    def read_hidden_text(self, filename):
        file_path_txt = os.path.join(self.here, filename)
        # Read the content of the file in binary mode
        with open(file_path_txt, "rb") as f:
            hidden_text_content = f.read()
        return hidden_text_content

    def calculate_length_of_hidden_text(self, filename):
        hidden_text_content = self.read_hidden_text(filename)
        # Convert each byte to its binary representation and join them
        return len("".join(format(byte, "08b") for byte in hidden_text_content))

    def find_raw_video_file(self, filename):
        file_extensions = [".mp4", ".mkv", ".avi"]
        for ext in file_extensions:
            file_path = os.path.join(self.here, filename + ext)
            if os.path.isfile(file_path):
                return file_path
        return None

    def convert_video(self, input_file, ffv1_video):
        # this function is the same as running this command line
        # ffmpeg -i video.mp4 -t 12 -c:v ffv1 -level 3 -coder 1 -context 1 -g 1 -slices 4 -slicecrc 1 -c:a copy output.mkv

        # in order to run any ffmpeg subprocess, you have to have ffmpeg installed into the computer.
        # https://ffmpeg.org/download.html

        # WARNING:
        # the ffmpeg you should download is not the same as the ffmpeg library for python.
        # you need to download the exe from the link above, then add ffmpeg bin directory to system variables
        output_file = os.path.join(self.here, ffv1_video)

        if not output_file.endswith(".mkv"):
            output_file += ".mkv"

        command = [
            "ffmpeg",
            "-y",
            "-i",
            input_file,
            "-t",
            "12",
            "-c:v",
            "ffv1",
            "-level",
            "3",
            "-coder",
            "1",
            "-context",
            "1",
            "-g",
            "1",
            "-slices",
            "4",
            "-slicecrc",
            "1",
            "-c:a",
            "copy",
            output_file,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Conversion successful: {output_file}")
            return output_file
        except subprocess.CalledProcessError as e:
            print(f"Error during conversion: {e}")

    def extract_audio(self, ffv1_video, audio_path):
        # Ensure the audio output file has the correct extension
        if not audio_path.endswith(".aac"):
            audio_path += ".aac"

        # Full path to the extracted audio file
        extracted_audio = os.path.join(self.here, audio_path)

        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        command = [
            "ffmpeg",
            "-i",
            ffv1_video,
            "-q:a",
            "0",
            "-map",
            "a",
            extracted_audio,
        ]
        try:
            result = subprocess.run(
                command, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
            )
            print(f"Audio successfully extracted to {extracted_audio}")
            print(result.stdout.decode())
            print(result.stderr.decode())
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")
            print(e.stdout.decode())
            print(e.stderr.decode())

    def read_frame_binary(self, frame_path):
        # Open the image and convert to binary
        with open(frame_path, "rb") as f:
            binary_content = f.read()
            binary_string = "".join(format(byte, "08b") for byte in binary_content)
        return binary_string

    def remove_frames_from_video(self, input_video, frames_to_remove):
        if not input_video.endswith(".mkv"):
            input_video += ".mkv"

        input_video_path = os.path.join(self.here, input_video)

        # Create a filter string to exclude specific frames
        filter_str = (
            "select='not("
            + "+".join([f"eq(n\,{frame})" for frame in frames_to_remove])
            + ")',setpts=N/FRAME_RATE/TB"
        )

        # Temporary output video path
        output_video_path = os.path.join(self.here, "temp_output.mkv")

        command = [
            "ffmpeg",
            "-y",
            "-i",
            input_video_path,
            "-vf",
            filter_str,
            "-c:v",
            "ffv1",
            "-level",
            "3",
            "-coder",
            "1",
            "-context",
            "1",
            "-g",
            "1",
            "-slices",
            "4",
            "-slicecrc",
            "1",
            "-an",  # Remove audio
            output_video_path,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Frames removed. Temporary video created at {output_video_path}")

            # Replace the original video with the new video
            os.replace(output_video_path, input_video_path)
            print(f"Original video replaced with updated video at {input_video_path}")

            # Re-add the trimmed audio to the new video
            self.trim_audio_and_add_to_video(input_video_path, frames_to_remove)
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")
            if os.path.exists(output_video_path):
                os.remove(output_video_path)

    def trim_audio_and_add_to_video(self, video_path, frames_to_remove):
        # Calculate the new duration based on the remaining frames
        fps = 60  # Assuming the framerate is 60 fps
        total_frames_removed = len(frames_to_remove)
        original_duration = self.get_video_duration(video_path)
        new_duration = original_duration - (total_frames_removed / fps)

        # Extract and trim the audio
        audio_path = os.path.join(self.here, "trimmed_audio.aac")
        command_extract_trim = [
            "ffmpeg",
            "-y",
            "-i",
            video_path,
            "-t",
            str(new_duration),
            "-q:a",
            "0",
            "-map",
            "a",
            audio_path,
        ]
        try:
            subprocess.run(command_extract_trim, check=True)
            print(f"Audio successfully trimmed and extracted to {audio_path}")

            # Add the trimmed audio back to the video
            final_video_path = video_path.replace(".mkv", "_final.mkv")
            command_add_audio = [
                "ffmpeg",
                "-y",
                "-i",
                video_path,
                "-i",
                audio_path,
                "-c:v",
                "copy",
                "-c:a",
                "aac",
                "-strict",
                "experimental",
                final_video_path,
            ]
            subprocess.run(command_add_audio, check=True)
            print(f"Final video with trimmed audio created at {final_video_path}")

            # Replace the original video with the final video
            os.replace(final_video_path, video_path)
            print(f"Original video replaced with final video at {video_path}")
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def get_video_duration(self, video_path):
        command = [
            "ffprobe",
            "-v",
            "error",
            "-show_entries",
            "format=duration",
            "-of",
            "default=noprint_wrappers=1:nokey=1",
            video_path,
        ]
        try:
            result = subprocess.run(
                command, check=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE
            )
            duration = float(result.stdout.decode().strip())
            return duration
        except subprocess.CalledProcessError as e:
            print(f"An error occurred while getting video duration: {e}")
            return 0.0

    def split_into_frames(self, ffv1_video, hidden_text_length):
        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        ffv1_video_path = os.path.join(self.here, ffv1_video)
        ffv1_video = cv2.VideoCapture(ffv1_video_path)

        currentframe = 0
        total_frame_bits = 0
        frames_to_remove = []

        while True:
            ret, frame = ffv1_video.read()
            if ret:
                name = os.path.join(self.here, "data", f"frame{currentframe}.png")
                print("Creating..." + name)
                cv2.imwrite(name, frame)

                current_frame_path = os.path.join(
                    self.here, "data", f"frame{currentframe}.png"
                )

                if os.path.exists(current_frame_path):
                    binary_data = self.read_frame_binary(current_frame_path)

                if (total_frame_bits // 8) >= hidden_text_length:
                    print("Complete")
                    break
                total_frame_bits += len(binary_data)
                frames_to_remove.append(currentframe)
                currentframe += 1
            else:
                print("Complete")
                break

        ffv1_video.release()

        # Remove the extracted frames from the original video
        self.remove_frames_from_video(ffv1_video_path, frames_to_remove)

    def stitch_frames_to_video(self, ffv1_video, framerate=60):
        # this command is another ffmpeg subcommand.
        # it takes every single frame from data1 directory and stitch it back into a ffv1 video
        if not ffv1_video.endswith(".mkv"):
            ffv1_video += ".mkv"

        output_video_path = os.path.join(self.here, ffv1_video)

        command = [
            "ffmpeg",
            "-y",
            "-framerate",
            str(framerate),
            "-i",
            os.path.join(self.frames_directory, "frame%d.png"),
            "-c:v",
            "ffv1",
            "-level",
            "3",
            "-coder",
            "1",
            "-context",
            "1",
            "-g",
            "1",
            "-slices",
            "4",
            "-slicecrc",
            "1",
            output_video_path,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Video successfully created at {output_video_path}")
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def add_audio_to_video(self, encoded_video, audio_path, final_video):
        # the audio will be lost during splitting and restitching.
        # that is why previously we separated the audio from video and saved it as aac.
        # now, we can put the audio back into the video, again using ffmpeg subcommand.

        if not encoded_video.endswith(".mkv"):
            encoded_video += ".mkv"

        if not final_video.endswith(".mkv"):
            final_video += ".mkv"

        if not audio_path.endswith(".aac"):
            audio_path += ".aac"

        final_output_path = os.path.join(self.here, final_video)

        command = [
            "ffmpeg",
            "-y",
            "-i",
            os.path.join(self.here, encoded_video),
            "-i",
            os.path.join(self.here, audio_path),
            "-c:v",
            "copy",
            "-c:a",
            "aac",
            "-strict",
            "experimental",
            final_output_path,
        ]
        try:
            subprocess.run(command, check=True)
            print(f"Final video with audio created at {final_output_path}")
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def concatenate_videos(self, video1_path, video2_path, output_path):
        if not video1_path.endswith(".mkv"):
            video1_path += ".mkv"
        if not video2_path.endswith(".mkv"):
            video2_path += ".mkv"
        if not output_path.endswith(".mkv"):
            output_path += ".mkv"

        video1_path = os.path.join(self.here, video1_path)
        video2_path = os.path.join(self.here, video2_path)
        output_video_path = os.path.join(self.here, output_path)

        # Create a text file with the paths of the videos to concatenate
        concat_list_path = os.path.join(self.here, "concat_list.txt")
        with open(concat_list_path, "w") as f:
            f.write(f"file '{video1_path}'\n")
            f.write(f"file '{video2_path}'\n")

        command = [
            "ffmpeg",
            "-y",
            "-f",
            "concat",
            "-safe",
            "0",
            "-i",
            concat_list_path,
            "-c",
            "copy",
            output_video_path,
        ]

        try:
            subprocess.run(command, check=True)
            print(f"Videos successfully concatenated into {output_video_path}")
            os.remove(concat_list_path)  # Clean up the temporary file
        except subprocess.CalledProcessError as e:
            print(f"An error occurred: {e}")

    def cleanup(self, files_to_delete):
        # Delete specified files
        for file in files_to_delete:
            file_path = os.path.join(self.here, file)
            if os.path.exists(file_path):
                os.remove(file_path)
                print(f"Deleted file: {file_path}")
            else:
                print(f"File not found: {file_path}")

        # Delete the frames directory and its contents
        if os.path.exists(self.frames_directory):
            shutil.rmtree(self.frames_directory)
            print(f"Deleted directory and its contents: {self.frames_directory}")
        else:
            print(f"Directory not found: {self.frames_directory}")


if __name__ == "__main__":
    stego = FFV1Steganography()

    # original video (mp4,mkv,avi)
    original_video = "video"
    # converted ffv1 video
    ffv1_video = "output"
    # extracted audio
    extracted_audio = "audio"
    # encoded video without sound
    encoded_video = "encoded"
    # final result video, encoded, with sound
    final_video = "result"

    # region --hidden text processing --
    hidden_text = stego.read_hidden_text("hiddentext.txt")
    hidden_text_length = stego.calculate_length_of_hidden_text("hiddentext.txt")
    # endregion

    # region -- raw video locating --
    raw_video_file = stego.find_raw_video_file(original_video)
    if raw_video_file:
        print(f"Found video file: {raw_video_file}")
    else:
        print("video.mp4 not found.")
    # endregion

    # region -- video processing INPUT--
    # converted_video_file = stego.convert_video(raw_video_file, ffv1_video)
    # if converted_video_file and os.path.exists(converted_video_file):
    #     stego.extract_audio(converted_video_file, extracted_audio)
    # else:
    #     print(f"Conversion failed: {converted_video_file} not found.")

    # stego.split_into_frames(ffv1_video, hidden_text_length * 50000)
    # endregion

    # region -- video processing RESULT --
    # stego.stitch_frames_to_video(encoded_video)
    stego.concatenate_videos(encoded_video, ffv1_video, final_video)
    # stego.add_audio_to_video(final_video, extracted_audio, final_video)
    # endregion

    # region -- cleanup --
    files_to_delete = [
        extracted_audio + ".aac",
        encoded_video + ".mkv",
        ffv1_video + ".mkv",
    ]

 stego.cleanup(files_to_delete)
    # endregion







  


  Edit for results expectations :
I dont know if there is a way to match the exact color encoding between the stitched png frames and the rest of the ffv1 video. Is there a way I can extract the frames such that the color, encoding or anything I may not know about ffv1 match the original ffv1 video ?

  


• Dreamcast SD Adapter and DreamShell

  31 décembre 2014, par Multimedia Mike — Sega Dreamcast

  Nope ! I’m never going to let go of the Sega Dreamcast hacking. When I was playing around with Dreamcast hacking early last year, I became aware that there is such a thing as an SD card adapter for the DC that plugs into the port normally reserved for the odd DC link cable. Of course I wanted to see what I could do with it.

  The primary software that leverages the DC SD adapter is called DreamShell. Working with this adapter and the software requires some skill and guesswork. Searching for these topics tends to turn up results from various forums where people are trying to cargo-cult their way to solutions. I have a strange feeling that this post might become the unofficial English-language documentation on the matter.

  Use Cases
  What can you do with this thing ? Undoubtedly, the primary use is for backing up (ripping) the contents of GD-ROMs (the custom optical format used for the DC) and playing those backed up (ripped) copies. Presumably, users of this device leverage the latter use case more than the former, i.e., download ripped games, load them on the SD card, and launch them using DreamShell.

  However, there are other uses such as multimedia playback, system exploration, BIOS reprogramming, high-level programming, and probably a few other things I haven’t figured out yet.

  Delivery
  I put in an order via the dc-sd.com website and in about 2 short months, the item arrived from China. This marked my third lifetime delivery from China and curiously, all 3 of the shipments have pertained to the Sega Dreamcast.

  
  

  

  Click for larger image

  
  

  I thought it was very interesting that this adapter came in such complete packaging. The text is all in Chinese, though the back states “Windows 98 / ME / 2000 / XP, Mac OS 9.1, LINUX2.4”. That’s what tipped me off that they must have just cannibalized some old USB SD card readers and packaging in order to create these. Closer inspection of the internals through the translucent pink case confirms this.

  Usage
  According to its change log, DreamShell has been around for a long time with version 1.0.0 released in February of 2004. The current version is 4.0.0 RC3. There are several downloads available :

  1. DreamShell 4.0 RC 3 CDI Image
  2. DreamShell 4.0 RC 3 + Boot Loader
  3. DreamShell 4.0 RC 3 + Core CDI image

  Option #2 worked for me. It contains a CDI disc image and the DreamShell files in a directory named DS/.

  Burn the CDI to a CD-R in the normal way you would burn a bootable Dreamcast disc from a CDI image. This is open-ended and left as an exercise to the reader, since there are many procedures depending on platform. On Linux, I used a small script I found once called burncdi-dc.sh.

  Then, copy the contents of the DS/ folder to an SD card. As for filesystem, FAT16 and FAT32 are both known to work. The files in DS/ should land in the root of the SD card ; the folder DS/ should not be in the root.

  Plug the SD card into the DC SD adapter and plug the adapter in the link cable port on the back of the Dreamcast. Then, boot the disc. If it works, you will see this minor corruption of the usual Sega licensing screen :

  
  
  

  Then, there will be a brief white-on-black text screen that explains the booting process :
  

  
  
  

  Then, there will be the main DreamShell logo :

  
  
  

  Finally, you will land on the DreamShell main desktop :

  
  
  

  Skepticism
  At first, I was supremely skeptical of the idea that this SD adapter could perform speedily enough to play games reasonably. This was predicated on the observation that my DC coder’s cable that I used to use for homebrew development could not transfer faster than 115200 bits/second, amounting to about 11 kbytes/sec. I assumed that this was a fundamental limitation of the link port.

  In fact, I ripped a few of my Dreamcast discs over a decade ago and still have those rips lying around. So I copied the ISO image of Resident Evil : Code Veronica — the game I personally played most on the DC — to the SD card (anywhere works) and used the “ISO loader” icon seen on the desktop above to launch the game.

  It works :

  
  
  

  The opening FMV plays at full speed. Everything loads as fast as I remember. I was quite surprised.

  Digression : My assumptions about serial speeds have often been mistaken. 10 years ago, I heard stories about how we would soon be able to watch streaming video on our cell phones. I scoffed because I thought the 56K limitation of dialup modems was some sort of fundamental speed-of-light type of limitation for telephony bandwidth, wired or wireless.

  The desktop menu also includes a ‘speedtest’ tool that profiles the write and read performance of your preferred storage medium. For my fastest SD card (a PNY 2 GB card) :

  
  
  

  This is probably more representative of the true adapter bandwidth as reading and writing is a good deal faster through more modern interfaces on PC and Mac with this same card.

  Look at the other options on the speedtest console. Hard drive ? Apparently, it’s possible, but it requires a good deal more hardware hacking than just purchasing this SD adapter.

  Ripping
  As you can see from the Resident Evil screenshot, playing games works quite nicely. How about ripping ? I’m pleased to say that DreamShell has a beautiful ripping interface :

  
  
  

  Enter a name for the disc (or read the disc label), select the storage medium, and let it, well, rip. It indicates which track it’s working on and the Sega logo acts as a progress bar, shading blue as the track rip progresses.

  I’m finally, efficiently, archiving that collection of Sega Dreamcast demo discs ; I’m hoping they’ll eventually find a home at the Internet Archive. How is overall ripping performance ? Usually about 38-40 minutes to rip a full 900-1000 MB. That certainly beats the 27-28 hours that were required when I performed the ripping at 11 kbytes/sec via the DC coders cable.

  All is well until I get a sector reading error :

  
  
  

  That’s when it can come in handy to have 3 DC consoles (see ?! not crazy !).

  Other Uses
  There’s a file explorer. You can browse the filesystem of the SD card, visual memory unit, or the CD portion of the GD-ROM (would be more useful if it accessed the GD area). There are FFmpeg files included. So I threw a random Cinepak file and random MPEG-1 file at it to see what happens. MPEG-1 didn’t do anything, but this Cinepak file from some Sierra game played handily :

  
  
  

  If you must enter strings, it helps to have a Dreamcast keyboard (which I do). Failing that, here’s a glimpse of the onscreen keyboard that DreamShell equips :

  
  
  

  Learning to use it is a game in itself.

  There is an option of installing DreamShell in the BIOS. I did not attempt this. I don’t know if it’s possible (not like there’s a lot of documentation)– perhaps a custom BIOS modchip is needed. But here’s what the screen looks like :

  
  
  

  There is also a plain console to interact with (better have a physical keyboard). There are numerous file manipulation commands and custom system interaction commands. I see one interesting command called ‘addr’ that looks useful for dumping memory regions to a file.

  A Lua language interpreter is also built in. I would love to play with this if I could ascertain whether DreamShell provided Dreamcast-specific APIs.

  Tips And Troubleshooting
  I have 3 Dreamcast consoles, affectionately named Terran, Protoss, and Zerg after the StarCraft II stickers with which they are adorned. Some seem to work better than others. Protoss seemed to be able to boot the DreamShell disc more reliably than the others. However, I was alarmed when it couldn’t boot one morning when it was churning the previous day.

  I think the problem is that it was just cold. That seemed to be the issue. I put in a normal GD-ROM and let it warm up on that disc for awhile and then DreamShell booted fine. So that’s my piece of cargo-culting troubleshooting advice.