mpeg4 codec encoding bitrate (-b) is not honored

[George Yohng]

Please check this example:
​http://pvtftp.trueinstruments.com/ffmpeg_bug.zip

The example .bat file is for Windows, but it should equally work under Linux. This is tested on Sep 15 snapshot of the GIT.

Running the command as such:

• ffmpeg -i video-2011-09-07-12-02-58.mp4 -b 18000k -an a.avi

Does not honor 18M bit rate, and instead encodes the file with 3-4Mbps bit rate with q constantly equal to 31.

Also, -qmin/-qmax spec is not honored, and if qmin/qmax is specified to, for example, 2-8, q still stays at 31.0

qscale is the only thing that works fine.

Jul 31 2010 doesn't seem to have this problem and encodes everything correctly.

[George Yohng]

There is a sample video, ffmpeg Sep 15 Windows build and a batch file under the link in the original bug description, but it doesn't seem to depend on this particular video. I tested it with several 1280x720 cellphone h264 input videos, and the problem is reproducible on ARM-Linux (Android) as well as on Windows.

[Carl Eugen Hoyos]

Since I cannot reproduce this issue (bitrate for minimal quantizer is <16Mb, quantizer is shown as 1-2 for -b18000k): Please add complete, uncut output of ffmpeg.

(Please do not offer FFmpeg binaries for download!)

[George Yohng]

FFmpeg output dump

[George Yohng]

I just did a refresh from git and cannot reproduce it either.

Please check the attached output of the affected Windows build of ffmpeg (and I had the same with Android with ffmpeg-HEAD-8af64e1 archive, whichever is that).

Apologies for submitting, if this is no longer valid.

[Carl Eugen Hoyos]

Please reopen if this is reproducible with current git head, oldabi, 0.8.3 or 0.7.4.