#341 Bitrate control does not work with h264

Dave Baker

Bitrate control does not work with video codec set to
h264. With the following command:

ffmpeg -b 192 -ab 48 -bufsize 256 -i "$1" -vcodec h264
-acodec aac -s 360x288 -cropleft 20 -cropright 20
-cropbottom 16 -croptop 16 -ac 1 -ar 22050 "$dest_file"

The expected result is that a file with an average
total bitrate of around 250kbps will be generated.

The actual result is a file with average total bitrate
of around 550kbps.

FFmpeg correctly does correctly report the bitrates
that is is attempting to achieve. Complete output follows:

ffmpeg version CVS, build 3342336, Copyright (c)
2000-2004 Fabrice Bellard
configuration: --enable-mp3lame --enable-libogg
--enable-vorbis --enable-theo
ra --enable-faad --enable-faac --enable-xvid
--enable-x264 --enable-gpl --disabl
e-ffserver --disable-ffplay
built on Dec 21 2005 15:44:47, gcc: 3.3.4
Input #0, avi, from 'ident_oil_music-mpeg4.avi':
Duration: 00:00:15.5, start: 0.000000, bitrate: 2708 kb/s
Stream #0.0, 25.00 fps(r): Video: mpeg4, yuv420p, 720x576
Stream #0.1: Audio: mp3, 48000 Hz, stereo, 192 kb/s
File 'test.mp4' already exists. Overwrite ? [y/N] y
Output #0, mp4, to 'test.mp4':
Stream #0.0, 25.00 fps(c): Video: h264, yuv420p,
320x256, q=2-31, 192 kb/s
Stream #0.1: Audio: aac, 22050 Hz, mono, 48 kb/s
Stream mapping:
Stream #0.0 -> #0.0
Stream #0.1 -> #0.1
[h264 @ 0x8498990]no need for a SAR
[h264 @ 0x8498990]VBV maxrate or buffer size specified,
but not both.
[h264 @ 0x8498990]using cpu capabilities MMX MMXEXT SSE
Press [q] to stop encoding
frame= 43 q=31.0 Lsize= 126kB time=1.7 bitrate=
video:113kB audio:11kB global headers:0kB muxing
overhead 1.430395%
[h264 @ 0x8498990]slice I:4 Avg QP:26.00 size:
6042 PSNR Mean Y:55.97 U:54.49 V:54.57 Avg:55.42
[h264 @ 0x8498990]slice P:39 Avg QP:30.54 size:
2321 PSNR Mean Y:38.82 U:37.11 V:37.10 Avg:38.16
[h264 @ 0x8498990]mb I I16..4: 51.9% 0.0% 48.1%
[h264 @ 0x8498990]mb P I16..4: 7.9% 0.0% 6.1%
P16..4: 26.6% 17.2% 7.5% 0.0% 0.0% skip:34.7%
[h264 @ 0x8498990]final ratefactor: 33.45
[h264 @ 0x8498990]PSNR Mean Y:40.418 U:38.726 V:38.722
Avg:39.768 Global:37.930 kb/s:533.39

This bug was encountered with the CVS version of ffmpeg
as of December 21st 2005.


  • This Sourceforge bug tracker here has been abandoned many years ago.

    Our new tracker can be found through http://www.ffmpeg.org/bugreports.html