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• Bash process substitution in Python with Popen

  7 septembre 2022, par moorej

  I'm attempting to create a looped video file by calling ffmpeg from the python subprocess library. Here's the part that's giving me problems :

  


  import subprocess as sp
sp.Popen(['ffmpeg', '-f', 'concat', '-i', "<(for f in ~/Desktop/*.mp4; do echo \"file \'$f\'\"; done)", "-c", "copy", "~/Desktop/sample3.mp4"])


  


  With the above code I'm getting the following error :

  


  <(for f in /home/delta/Desktop/*.mp4; do echo "file '$f'"; done): No such file or directory


  


  I did find a similarly phrased question here. But I'm not sure how the solution might apply to solving my issue.

  


• Trying to fetch all audio streams with FFmpeg Python

  27 juillet 2022, par Apollo

  I'm using ffmpeg-python to fetch streams from a video and write some parameters (codec_name, resolution, etc.) for each stream into csv.

  


  video = 'test.mkv'
probe = ffmpeg.probe(video)
video_stream = next((stream for stream in probe['streams'] if stream['codec_type'] == 'video'), None)
print(video_stream['codec_long_name'])
audio_stream = next((stream for stream in probe['streams'] if stream['codec_type'] == 'audio'), None)
...


  


  My problem is that it works well for a video stream, but not for multiple audio (or subtitles) streams. If the video has several audio streams it returns only one audio stream.

  


  I've tried another approach, but it returns some streams 2-3 times and I get duplicates. So if the video sample has 4 audio tracks, I end up with 9 audio streams instread of 4.

  


  audio_streams = []
for audio in (probe['streams']):
    if (audio['codec_type'] == 'audio'):
        audio_streams.append(audio)
        pprint(audio_streams)


  


  All other ideas I tried don't work, I'm new to programming and I'm stuck with it.
How can I get all audio streams from a file without duplicates ?

  


• How do I connect two GIFs to play one after another in Python ?

  9 novembre 2022, par Andrew

  If I have two GIFs, GIF 1 being 10 seconds long and GIF 2 being 5 seconds long, is there a way to connect them so the final GIF is a total of 15 seconds long ?

  


  Would I have to loop through each frame of both the GIFs with imageio.mimread() and output, once all the frames are read in memory ?

  


  Or is there another way by knowing the start and end times and shifting it ?

  


  Edit :
The solution presented by FirefoxMetzger is extremely Pythonic, ideal if you do not wish to install other software / packages like gifsicle.

  


  import imageio.v3 as iio
import numpy as np

frames = np.vstack([
    iio.imread("imageio1.gif"),
    iio.imread("imageio2.gif"),
])

# get duration each frame is displayed
iio.imwrite("imageio_combined.gif", frames)


  


  This completes in 15.6 seconds for two GIFs, each containing 100 frames.

  


  However, if runtime is important, I recommend gifsicle :

  


  gifsicle(
    sources=["imageio1.gif", "imageio2.gif"], # or just omit it and will use the first source provided.
    destination="imageio3.gif",
    options=["--optimize=2", "--threads=2", "--no-conserve-memory"]
)


  


  This completes in 4.8 seconds, which is three times as fast.