Ffmpeg-python: Duplicate option names via kwargs?

[monokal]

Afternoon!

So, from the README:

Special option names:
Arguments with special names such as -qscale:v (variable bitrate), -b:v (constant bitrate), etc. can be specified as a keyword-args dictionary as follows:

(
ffmpeg
.input('in.mp4')
.output('out.mp4', **{'qscale:v': 3})
.run()
)

However, if you're running multiple renditions, such as in the example below, how could this be achieved? The kwargs dictionary would have to contain duplicate keys, which obviously isn't possible:

ffmpeg -hide_banner -y -i beach.mkv \
  -vf scale=w=640:h=360:force_original_aspect_ratio=decrease -c:a aac -ar 48000 -c:v h264 -profile:v main -crf 20 -sc_threshold 0 -g 48 -keyint_min 48 -hls_time 4 -hls_playlist_type vod  -b:v 800k -maxrate 856k -bufsize 1200k -b:a 96k -hls_segment_filename beach/360p_%03d.ts beach/360p.m3u8 \
  -vf scale=w=842:h=480:force_original_aspect_ratio=decrease -c:a aac -ar 48000 -c:v h264 -profile:v main -crf 20 -sc_threshold 0 -g 48 -keyint_min 48 -hls_time 4 -hls_playlist_type vod -b:v 1400k -maxrate 1498k -bufsize 2100k -b:a 128k -hls_segment_filename beach/480p_%03d.ts beach/480p.m3u8 \
  -vf scale=w=1280:h=720:force_original_aspect_ratio=decrease -c:a aac -ar 48000 -c:v h264 -profile:v main -crf 20 -sc_threshold 0 -g 48 -keyint_min 48 -hls_time 4 -hls_playlist_type vod -b:v 2800k -maxrate 2996k -bufsize 4200k -b:a 128k -hls_segment_filename beach/720p_%03d.ts beach/720p.m3u8 \
  -vf scale=w=1920:h=1080:force_original_aspect_ratio=decrease -c:a aac -ar 48000 -c:v h264 -profile:v main -crf 20 -sc_threshold 0 -g 48 -keyint_min 48 -hls_time 4 -hls_playlist_type vod -b:v 5000k -maxrate 5350k -bufsize 7500k -b:a 192k -hls_segment_filename beach/1080p_%03d.ts beach/1080p.m3u8

What I have so far is as follows, but obviously can't be expanded in to kwargs, so pretty useless:

renditions = [
    {'resolution': '426x240', 'bitrate': '400k', 'audiorate': '64k'},
    {'resolution': '640x360', 'bitrate': '800k', 'audiorate': '96k'},
    {'resolution': '842x480', 'bitrate': '1400k', 'audiorate': '128k'},
    {'resolution': '1280x720', 'bitrate': '2800k', 'audiorate': '128k'},
    {'resolution': '1920x1080', 'bitrate': '5000k', 'audiorate': '192k'}
]

ffmpeg_params = {'renditions': []}

for rendition in renditions:
    ffmpeg_params['renditions'].append(
        {
            'vf': "scale=w={}:h={}:force_original_aspect_ratio=decrease".format(
                rendition['resolution'].split('x')[0], rendition['resolution'].split('x')[1]),
            'c:a': 'aac',
            'ar': '48000',
            'c:v': 'h264',
            'profile:v': 'main',
            'crf': '20',
            'sc_threshold': '0',
            'g': '48',
            'keyint_min': '48',
            'hls_time': '4',
            'hls_playlist_type': 'vod',
            'b:v': f"{rendition['bitrate']}",
            'maxrate': '856k',
            'bufsize': '1200k',
            'b:a': f"{rendition['audiorate']}",
            'hls_segment_filename': f"{rendition['resolution'].split('x')[1]}p_{segment_format}"
        }
    )

I can see a few references to multiple inputs and concat in the README, but I'm not grasping how to make use of these, if they're even relevant to my issue.

Thanks in advance.

[kkroening]

In that particular case, it looks like you have multiple outputs and as such, multiple calls to .output can be made, each with its own kwargs. The multi-output filter graph can be combined and executed using .merge_outputs (see examples).

[monokal]

Outstanding support, thank you @kkroening

Here's what I've done taking your support on-board:

import ffmpeg

input_file = 'input.mp4'
segment_format = '%03d.ts'  # Will be prepended with "<resolution>_"

renditions = [
    {'name': '240p', 'resolution': '426x240', 'bitrate': '400k', 'audiorate': '64k'},
    {'name': '360p', 'resolution': '640x360', 'bitrate': '700k', 'audiorate': '96k'},
    {'name': '480p', 'resolution': '854x480', 'bitrate': '1250k', 'audiorate': '128k'},
    {'name': 'HD 720p', 'resolution': '1280x720', 'bitrate': '2500k', 'audiorate': '128k'},
    {'name': 'HD 720p 60fps', 'resolution': '1280x720', 'bitrate': '3500k', 'audiorate': '128k'},
    {'name': 'Full HD 1080p', 'resolution': '1920x1080', 'bitrate': '4500k', 'audiorate': '192k'},
    {'name': 'Full HD 1080p 60fps', 'resolution': '1920x1080', 'bitrate': '5800k', 'audiorate': '192k'},
    {'name': '4k', 'resolution': '3840x2160', 'bitrate': '14000k', 'audiorate': '192k'},
    {'name': '4k 60fps', 'resolution': '3840x2160', 'bitrate': '23000k', 'audiorate': '192k'}
]

ffmpeg_input_stream = ffmpeg.input(input_file)
ffmpeg_output_streams = []

for rendition in renditions:
    ffmpeg_params = {
        'vf': "scale=w={}:h={}:force_original_aspect_ratio=decrease".format(
            rendition['resolution'].split('x')[0], rendition['resolution'].split('x')[1]),
        'c:a': 'aac',
        'ar': '48000',
        'c:v': 'h264',
        'profile:v': 'main',
        'crf': '20',
        'sc_threshold': '0',
        'g': '48',
        'keyint_min': '48',
        'hls_time': '4',
        'hls_playlist_type': 'vod',
        'b:v': f"{rendition['bitrate']}",
        'maxrate': '856k',
        'bufsize': '1200k',
        'b:a': f"{rendition['audiorate']}",
        'hls_segment_filename': f"{rendition['resolution'].split('x')[1]}p_{segment_format}"
    }

    ffmpeg_output_streams.append(
        ffmpeg.output(
            ffmpeg_input_stream,
            f"{rendition['resolution'].split('x')[1]}p.m3u8",
            **ffmpeg_params
        )
    )

output_streams = ffmpeg.merge_outputs(*ffmpeg_output_streams)

ffmpeg.run(output_streams)

[kkroening]

Thanks for sharing, @monokal