[FFmpeg-devel] [PATCH 2/3] ffmpeg.c: refine picking default video stream

Michael Niedermayer michael at niedermayer.cc
Wed Oct 14 20:09:31 EEST 2020


On Wed, Oct 14, 2020 at 10:53:10AM +0200, Anton Khirnov wrote:
> Use a floating-point score value to take into account bitrate, when
> multiple streams with the same resolution are present.
> 
> Stop accessing private AVStream.codec_info_nb_frames field, as the
> sample in question
> http://samples.ffmpeg.org/ffmpeg-bugs/trac/ticket2639/Thailand-Wave.wmv
> is now handled by the above change.
> ---
>  fftools/ffmpeg_opt.c | 23 ++++++++++++++++++-----
>  1 file changed, 18 insertions(+), 5 deletions(-)

Breaks:
-i tickets/4496/08_lect_01.rm  file.avi

as refernce here is what ffmpeg shows about the streams:
    Stream #0:0: Audio: sipr (sipr / 0x72706973), 8000 Hz, mono, flt, 4 kb/s
    Stream #0:1: Audio: sipr (sipr / 0x72706973), 8000 Hz, mono, flt, 8 kb/s
    Stream #0:2: Audio: cook (cook / 0x6B6F6F63), 22050 Hz, mono, fltp, 4 kb/s
    Stream #0:3: Audio: sipr (sipr / 0x72706973), 8000 Hz, mono, flt, 4 kb/s
    Stream #0:4: Video: rv20 (RV20 / 0x30325652), yuv420p, 320x240, 252 kb/s, 15 fps, 15 tbr, 1k tbn, 1k tbc
    Stream #0:5: Video: rv20 (RV20 / 0x30325652), yuv420p, 320x240, 252 kb/s, 15 fps, 15 tbr, 1k tbn, 1k tbc
    Stream #0:6: Video: rv20 (RV20 / 0x30325652), yuv420p, 320x240, 252 kb/s, 15 fps, 15 tbr, 1k tbn, 1k tbc
    Stream #0:7: Video: rv20 (RV20 / 0x30325652), yuv420p, 320x240, 252 kb/s, 15 fps, 15 tbr, 1k tbn, 1k tbc
    Stream #0:8: Video: rv20 (RV20 / 0x30325652), yuv420p, 320x240, 252 kb/s, 15 fps, 15 tbr, 1k tbn, 1k tbc
    Stream #0:9: Video: rv20 (RV20 / 0x30325652), yuv420p, 320x240, 252 kb/s, 15 fps, 15 tbr, 1k tbn, 1k tbc
    Stream #0:10: Video: rv20 (RV20 / 0x30325652), yuv420p, 320x240, 252 kb/s, 15 fps, 15 tbr, 1k tbn, 1k tbc
    Stream #0:11: Video: rv20 (RV20 / 0x30325652), yuv420p, 320x240, 252 kb/s, 15 fps, 15 tbr, 1k tbn, 1k tbc
    Stream #0:12: Video: rv20 (RV20 / 0x30325652), yuv420p, 320x240, 252 kb/s, 15 fps, 15 tbr, 1k tbn, 1k tbc
    Stream #0:13: Video: rv20 (RV20 / 0x30325652), yuv420p, 320x240, 252 kb/s, 15 fps, 15 tbr, 1k tbn, 1k tbc

sample should be here according to the ticket:
https://samples.ffmpeg.org/ffmpeg-bugs/trac/ticket2152/

I dont think you can reliably detect non empty streams from the header alone
in every case.

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If the United States is serious about tackling the national security threats 
related to an insecure 5G network, it needs to rethink the extent to which it
values corporate profits and government espionage over security.-Bruce Schneier
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