[FFmpeg-devel] [PATCH] doc/ffmpeg - rewrite Stream Selection chapter

Carl Eugen Hoyos ceffmpeg at gmail.com
Wed May 30 02:27:14 EEST 2018

2018-05-27 6:16 GMT+02:00, Gyan Doshi <gyandoshi at gmail.com>:

> v2 attached.

> +In the absence of any map options for a particular output file, ffmpeg inspects the output
> +format to check which type of streams can be included in it, viz. video, audio and/or

Sorry, what is "viz."?

> +subtitles. For each acceptable stream type, ffmpeg will pick one stream, when available,
> +from among all the inputs.

I don't think this is correct, not every stream type is picked.
Or do I misunderstand?

> +It will select that stream based upon the following criteria:
> +@*
> +@*for video, it is the stream with the highest resolution,
> +@*for audio, it is the stream with the most channels,
> +@*for subtitles, it is the first subtitle stream

Please remove the actual current criteria:
This is just the current state of the implementation, for one
of the above, this is obviously not a good choice, for the
others, we could find better criteria.
Or mention that they may all change at any point.

> +The output format's default subtitle encoder may be text-based or image-based, and only a
> +subtitle stream of the same type can be chosen.

I wish that were true but I fear it isn't;-(


> +In the case where several streams of the same type rate equally, the stream with the
> lowest
> +index is chosen.

Please remove this.

All-in-all, this is far too complicated imo.

Please resend, Carl Eugen

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