Detecting AV1-encoded videos with Python (alexwlchan.net)

Somehow I thought this was going to be about detecting AV1 based on the decoded video frames, which would have been interesting!

Is launching an ffmpeg process so heavyweight that there's a reason to avoid it? If anything, it feels like it would trivialize parallelism, which is probably a feature, not a bug, if you have a bunch of videos to go through.

My first question is, where is this guy getting AV1 videos? Never seen these on the high seas.

Also, given that these videos are going to be reencoded, which is tremendously expensive, I feel that any optimization in this step is basically premature. Naively launching ffprobe 10,000 times is probably still less heavyweight than 1 reencode.

    av1_videos = {
        p
        for p in glob.glob("**/*.mp4", recursive=True)
        if is_av1_video(p)
    }

    assert av1_videos == set()

Building a set just to check if it's empty is a bit more complexity than necessary. A more direct way that also bails out early:

    assert not any(is_av1_video(p) for p in glob.glob("**/*.mp4", recursive=True))

Equivalently (de Morgan's law):

    assert all(not is_av1_video(p) for p in glob.glob("**/*.mp4", recursive=True))

> I’ve saved some AV1-encoded videos that I can’t play on my iPhone.

Sure you can. Install VLC on your phone and you'll be able to play the AV1 videos. Even the iPhone 7 released in 2016 can play AV1 video.

Don't agonise over battery life. The dav1d decoder for AV1 is great:

https://www.reddit.com/r/AV1/comments/1cf7eti/av1_dav1d_play...

https://www.reddit.com/r/AV1/comments/1cg2wv4/dav1d_battery_...

https://www.reddit.com/r/AV1/comments/1cgyace/dav1d_battery_...

https://www.reddit.com/r/AV1/comments/1chpz2r/dav1d_battery_...

Note that ffprobe can output JSON which is much easier to handle than CSV. I have this snippet in my bashrc:

ffpj() { for f in "$@"; do ffprobe -v quiet -print_format json -show_format -show_streams "$f"; done }

This is a perfectly fine blog post, but is about something so basic I don't understand why it's submitted to HN.

Yes, ffprobe and mediainfo are the two common tools for this. This just feels like something that belongs as the answer to an everyday StackOverflow question. I don't understand what it's doing on the front page of HN.

There's a python module for this:

https://pypi.org/project/ffmpeg-python/

https://github.com/kkroening/ffmpeg-python

  >>> import ffmpeg
  >>> video_metadata = ffmpeg.probe('test.mp4')
  >>> print(video_metadata['streams'][0]['codec_name'])
  h264