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• Best way to cut by audio level in ffmpeg ?

  17 octobre 2019, par Aayla Pozho

  I have several hundred video files with varying amounts of frames that are silent but not blank at the beginning (5-10 seconds). I need to remove these few seconds of silence based on the audio levels, and I would prefer to do it as efficiently as possible as I have several hundred of these files to process.

  I recently found this post and confirmed that all audio tracks have a value of "-inf" until the point I want to cut, but I’m not entirely sure where to proceed from here.

• FFMPEG set ZxY width and height thumbnail while keeping aspect ratio with padding

  22 janvier 2023, par AlanSTACK

  I have been searching Stack Overflow for code to create thumbnails using FFmpeg.

  


  But the options I've come across either result in distorted thumbnails when using the -s 100x100 and a specific frame, or only correctly scale one side of the image when using -vf 100 :-1. This is an issue for me as all thumbnails need to be the same size.

  


  Is there a way to achieve both a set height/width and maintain a consistent aspect ratio, such as filling in blank spaces with black boxes ?

  


• Transcoding Videos Using FastAPI and ffmpeg

  15 janvier 2024, par Sanji Vinsmoke

  I created an API using Fast API where I upload one or more videos, may specify the resolution of transcoding, and the output is transcoded video from 240p upto the resolution I specified. Available resolutions are - 240p, 360p, 480p, 720p, 1080p. I used ffmpeg for the transcoding job.

  


  The problem that is bugging me since yesterday is that, after deploying to the s3 bucket and adding the url for the index.m3u8 file in any hls player, the video is blank. Only the audio and streaming are working. I have tried tweaking with the parameters in the ffmpeg parameters, the error is still there. I tried manually transcoding a video file locally, even that video's index.m3u8 file is blank in live version. I added the relevant codes for this project. I implemented each feature one by one, but I simply cannot find the reason why the video is totally blank on live.

  


  def transcode_video(input_path, output_folder, res, video_id, video_resolution, progress_bar=None):
    # Transcode the video into .m3u8 format with segment format
    output_path = os.path.join(output_folder, f"{res}_{video_id}.m3u8")

    # Use subprocess for command execution
    chunk_size = 1 # Specify the desired chunk size in seconds

    transcode_command = [
        "ffmpeg", "-i", input_path, "-vf", f"scale={res}:'trunc(ow/a/2)*2'", "-c:a", "aac", "-strict", "-2",
        "-f", "segment", "-segment_time", str(chunk_size), "-segment_list", output_path, "-segment_format", "ts",
        f"{output_path.replace('.m3u8', '_%03d.ts')}"
    ]

    try:
        subprocess.run(transcode_command, check=True, capture_output=True)
    except subprocess.CalledProcessError as e:
        print(f"Error during transcoding: {e}")
        print(f"FFmpeg error output: {e.stderr}")
        # Continue with the next video even if an error occurs
        return False

    # Update the progress bar
    if progress_bar:
        progress_bar.update(1)
    return True


def get_bandwidth(resolution):
    # Define a simple function to calculate bandwidth based on resolution
    resolutions_and_bandwidths = {
        240: 400000,
        360: 850000,
        480: 1400000,
        720: 2500000,
        1080: 4500000,
    }
    
    return resolutions_and_bandwidths.get(resolution, 0)
def create_index_m3u8(video_id, resolutions_to_transcode):
    # Write the index.m3u8 file
    index_m3u8_path = os.path.join(OUTPUT_FOLDER, f"index_{video_id}.m3u8")
    with open(index_m3u8_path, "w") as index_file:
        index_file.write("#EXTM3U\n")
        index_file.write("#EXT-X-VERSION:3\n")

        for res in resolutions_to_transcode:
            aspect_ratio = 16 / 9
            folder_name = f"{res}p_{video_id}"
            resolution_file_name = f"{res}_{video_id}.m3u8"
            index_file.write(
                f"#EXT-X-STREAM-INF:BANDWIDTH={get_bandwidth(res)},RESOLUTION={int(res * aspect_ratio)}x{res}\n{folder_name}/{resolution_file_name}\n"
            )


  


  I tried reducing or increasing chunk size, adding codecs, setting up dimensions. Where am I doing wrong ?

  


  My python version is 3.8.18, ffmpeg version-4.4.4, ffmpeg-python version-0.2.0