Convert videos to Chromebook-compatible format, if necessary

fixvid

#!/usr/bin/env python3

import sys
import subprocess
import json
import os

# Supported by Chrome OS according to https://www.chromium.org/audio-video
ACCEPTABLE_VIDEO=('theora', 'vp8', 'vp9', 'h264', 'mpeg4')

ACCEPTABLE_AUDIO=('aac', 'mp3', 'vorbis', 'opus', 'pcm_mulaw', 'pcm_f32le',
                  'pcm_s16le', 'pcm_u8', 'flac', 'amr_nb', 'amr_wb')

def check_codec(filename):
    video_ok = audio_ok = False

    output = subprocess.run(['ffprobe', '-i', filename,
                             '-of', 'json', '-show_streams'],
                            stdout=subprocess.PIPE,
                            stderr=subprocess.DEVNULL)
    dat = json.loads(output.stdout.decode('utf-8'))
    for stream in dat.get('streams', []):
        #print(repr(stream))

        if stream.get('codec_type', '') == 'video' and \
           stream.get('codec_name', '') in ACCEPTABLE_VIDEO:
            video_ok = True

        if stream.get('codec_type', '') == 'audio' and \
           stream.get('codec_name', '') in ACCEPTABLE_AUDIO:
            audio_ok = True

    return (video_ok, audio_ok)

for filename in sys.argv[1:]:
    video_ok, audio_ok = check_codec(filename)
    if (not video_ok) or (not audio_ok):
        print(filename, 'needs reencoding')
        basename, ext = os.path.splitext(filename)

        acodec = 'copy' if audio_ok else 'libvo_aacenc'
        if video_ok:
            vparams = ['-codec:v', 'copy']
        else:
            vparams = ['-codec:v', 'libx264',
                       '-preset', 'slower',
                       '-tune', 'film',
                       '-crf', '20',
                       '-profile:v', 'high', # TiVo compatibility
                       '-level', '4.1',      # TiVo compatibility
                       '-movflags', '+faststart']
            ext = '.m4v'

        outfile = basename+'-fixed'+ext

        #print(outfile, acodec, vparams)
        subprocess.run(['ffmpeg', '-threads', '0', '-i', filename] +
                       vparams +
                       ['-codec:a', acodec, '-b:a', '192k', '-y', outfile])