[FFmpeg-trac] #9201(undetermined:reopened): -c:v mpeg2video ignoring -qmin+qmax

[FFmpeg]

#9201: -c:v mpeg2video ignoring -qmin+qmax
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             Reporter:  Warren       |                    Owner:  (none)
  Young                              |
                 Type:  defect       |                   Status:  reopened
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  unspecified  |               Resolution:
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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Comment (by IvanDSM):

 To aid in debugging this, I've come up with a minimal reproducible example
 using public domain footage, with a much simpler set of command line
 arguments.

 First, download the public domain 1903 film of Alice in Wonderland from
 Wikimedia Commons at the following link:
 https://upload.wikimedia.org/wikipedia/commons/b/bb/Alice_in_Wonderland_%281903%29.ogv

 Then, run the following command in the directory where you downloaded the
 film:

 {{{ffmpeg -i "Alice_in_Wonderland_(1903).ogv" -c:v mpeg2video -b:v 1024k
 -maxrate:v 1575k -bufsize:v 921.6k -qmin:v 4 -qmax:v 20 -an alice.mkv}}}

 The resulting output will show the non-working qmin/qmax problem:

 {{{  Stream #0:0: Video: mpeg2video (Main) (mpg2 / 0x3267706D),
 yuv420p(tv, progressive), 480x360 [SAR 1:1 DAR 4:3], q=2-31, 1024 kb/s,
 29.97 fps, 1k tbn}}}

 The live updating line at the bottom will also show values of q under 4
 being used extremely often.

 Adding -loglevel debug shows that the options are supposedly being
 correctly parsed:

 {{{
 Splitting the commandline.
 Reading option '-loglevel' ... matched as option 'loglevel' (set logging
 level) with argument 'debug'.
 Reading option '-i' ... matched as input url with argument
 'Alice_in_Wonderland_(1903).ogv'.
 Reading option '-c:v' ... matched as option 'c' (select encoder/decoder
 ('copy' to copy stream without reencoding)) with argument 'mpeg2video'.
 Reading option '-b:v' ... matched as option 'b' (video bitrate (please use
 -b:v)) with argument '1024k'.
 Reading option '-maxrate:v' ... matched as AVOption 'maxrate:v' with
 argument '1575k'.
 Reading option '-bufsize:v' ... matched as AVOption 'bufsize:v' with
 argument '921.6k'.
 Reading option '-qmin:v' ... matched as AVOption 'qmin:v' with argument
 '4'.
 Reading option '-qmax:v' ... matched as AVOption 'qmax:v' with argument
 '20'.
 Reading option '-an' ... matched as option 'an' (disable audio) with
 argument '1'.
 Reading option 'alice.mkv' ... matched as output url.
 Finished splitting the commandline.
 }}}

 Please note that although I've opted to use {{{-qmin:v}}} and
 {{{-qmax:v}}} in this example, removing the {{{:v}}} suffix makes no
 difference.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/9201#comment:5>
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