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• ffmpeg : speed up AND rotate video

  30 juillet 2021, par LFPGaming

  This is my current script that I'm trying to use to speed up the playspeed and rotate my video by 90', but it doesn't work when I include the transpose=1 argument.

  


  "C:\ffmpeg-win64\bin\ffmpeg.exe" -i "C:\video1.mkv" -vf "setpts=PTS/60" "transpose=1" -an -crf 18 "C:\video2.mkv"


  


  Script works without the transpose argument and speeds up my video perfectly, but Script won't run once I try to rotate the video by 90' and outputs an error :

  


  Unable to find a suitable output format for 'transpose=1'
transpose=1: Invalid argument


  


  Can anyone tell me where I'm going wrong ?

  


• How do I play back video on Android with custom playback speed ?

  13 novembre 2015, par guidow

  I want to play back a video in Android, rendering it to a SurfaceTexture or something else that is usable as an OpenGL ES texture, but I need very precise control over the playback speed of the video to synchronize it to a stream of external events. These events will happen at a roughly predictable speed, but the exact speed will depend on many small mechanical details, influenced by many small factors, including the weather (and possibly even the phase of the moon...).

  The android.media.MediaPlayer class provided by android allows rendering to a SurfaceTexture (and the 360Videos app from the Oculus Mobile SDK successfully uses that feature), but unfortunately does not seem to allow altering the playback speed, at least not as far as I could tell from the documentation here.

  I have tried pausing and resuming the playback using pause() and start() respectively, to influence the playback speed, but that leads to extremely choppy and slow playback. My idea here was to make the video have a higher framerate than would ever be needed, and to then manually retard every frame until it actually needs to be shown. From the messages in the log, it looks to me like the MediaPlayer class will release various needed resources on pause and rerequest them on resume, which obviously kills performance if you do that once per frame.

  Another option I am looking at is ffmpeg. This one seems like it will do what i want, it doesn’t do any timings itself, it just decodes frames whenever I tell it to to a buffer, leaving me to use it however I want, whenever I want. The obvious drawback is that ffmpeg, at least on android, doesn’t do hardware decoding and probably won’t be able to decode 4K media in realtime.

  Yet another thing I was looking at was OpenMAX AL. Unfortunately, OpenMax AL is pretty hard to get into. I haven’t found any good beginner’s documentation yet, only some old, maybe outdated, READMEs as well as the interface specification from Khronos. The latter is a very long and cumbersome read, though, and I couldn’t yet even figure out if OpenMAX AL will even allow me to do my own timings...

• How to Bulk Speed UP and Crop Videos FFMPEG

  6 septembre 2023, par Usemo Shank

  I have videos in (input) folder that is located on the root of the script, I also have output folder on the root, The input folder has several videos that i want to speed up in bulk by 1.1 percent, I also want to cropt the videos by 90 percent (Meaning 90 Percent of original video is visible).

  


  I have a code that does not function well. Here is the code I have

  


   import os
import subprocess

# Define input and output directories
input_folder = "input"
output_folder = "output"

# Create the output directory if it doesn't exist
if not os.path.exists(output_folder):
    os.makedirs(output_folder)

# List all video files in the input directory
input_files = [f for f in os.listdir(input_folder) if f.endswith(('.mp4', '.avi', '.mkv'))]

# Speed up and crop each video
for input_file in input_files:
    input_path = os.path.join(input_folder, input_file)
    output_file = os.path.splitext(input_file)[0] + "_speed_crop.mp4"
    output_path = os.path.join(output_folder, output_file)

    # FFmpeg command to speed up video by 1.1x and crop to 90%
    ffmpeg_command = [
        "ffmpeg",
        "-i", input_path,
        "-vf", "setpts=1.1*PTS,crop=in_w*0.9:in_h*0.9",
        "-c:v", "libx264",
        "-crf", "20",
        "-c:a", "aac",
        "-strict", "experimental",
        output_path
    ]

    # Run FFmpeg command
    subprocess.run(ffmpeg_command)

print("Conversion complete.")