[Bug 356322] [NEW] using -qscale in ffmpeg doesn't have any effect on coding

Nido Media nido at foxserver.be
Mon Apr 6 14:38:27 UTC 2009 

Public bug reported:

Binary package hint: ffmpeg

using ffmpeg comming with ubuntu jaunty (which is FFmpeg version
0.5=-svn17737+3:0.svn20090303-1ubuntu4); usage of the -qscale rather then -b
doesn't change the end result file size. In fact; coding a flv video five times
with qscale going from 1 to 5 has no effect; using 25 doesn't quite make the
video any smaller or less nice to watch.

Originally found this with trying to transcode vob mpeg to a theora; trying
-qmin, -qmax -sameq seems to have the same effect.


I guess the default of 200kb/s for the bitrate setting is taking precedence over
what's set for the quantizer


Here's some command line session which shows the problem. This isn't limited to vob -> flv; qscale doesn't work for theora->theora as well, (and probably a lot more, if not everything).


0 nido at toad:~/ for x in 1 2 3 4 5; do ffmpeg -y -i HARRY_POTTER_GOBLET_OF_FIRE1.vob -croptop 80 -cropbottom 80 -t 00:01:00 -ss 00:00:00 -an -sameq -f flv -qscale $x video$x.flv; done

FFmpeg version 0.5-svn17737+3:0.svn20090303-1ubuntu4, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --extra-version=svn17737+3:0.svn20090303-1ubuntu4 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --disable-stripping --disable-vhook --enable-libdc1394 --enable-shared --disable-static
  libavutil     49.15. 0 / 49.15. 0
  libavcodec    52.20. 0 / 52.20. 0
  libavformat   52.31. 0 / 52.31. 0
  libavdevice   52. 1. 0 / 52. 1. 0
  libavfilter    0. 4. 0 /  0. 4. 0
  libswscale     0. 7. 1 /  0. 7. 1
  libpostproc   51. 2. 0 / 51. 2. 0
  built on Mar 23 2009 07:13:25, gcc: 4.3.3

Seems stream 0 codec frame rate differs from container frame rate: 50.00 (50/1) -> 25.00 (25/1)
Input #0, mpeg, from 'HARRY_POTTER_GOBLET_OF_FIRE1.vob':
  Duration: 01:15:42.86, start: 0.052000, bitrate: 12699 kb/s
    Stream #0.0[0x1e0]: Video: mpeg2video, yuv420p, 720x576 [PAR 64:45 DAR 16:9], 7500 kb/s, 25 tbr, 90k tbn, 50 tbc
    Stream #0.1[0x80]: Audio: ac3, 48000 Hz, 5.1, s16, 384 kb/s
    Stream #0.2[0x81]: Audio: ac3, 0 channels, s16
Output #0, flv, to 'video1.flv':
    Stream #0.0: Video: flv, yuv420p, 720x416 [PAR 227:221 DAR 10215:5746], q=2-31, 200 kb/s, 90k tbn, 25 tbc
Stream mapping:
  Stream #0.0 -> #0.0
Press [q] to stop encoding
frame= 1501 fps=103 q=0.0 Lsize=   12920kB time=60.04 bitrate=1762.8kbits/s    
video:12896kB audio:0kB global headers:0kB muxing overhead 0.183273%
FFmpeg version 0.5-svn17737+3:0.svn20090303-1ubuntu4, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --extra-version=svn17737+3:0.svn20090303-1ubuntu4 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --disable-stripping --disable-vhook --enable-libdc1394 --enable-shared --disable-static
  libavutil     49.15. 0 / 49.15. 0
  libavcodec    52.20. 0 / 52.20. 0
  libavformat   52.31. 0 / 52.31. 0
  libavdevice   52. 1. 0 / 52. 1. 0
  libavfilter    0. 4. 0 /  0. 4. 0
  libswscale     0. 7. 1 /  0. 7. 1
  libpostproc   51. 2. 0 / 51. 2. 0
  built on Mar 23 2009 07:13:25, gcc: 4.3.3

Seems stream 0 codec frame rate differs from container frame rate: 50.00 (50/1) -> 25.00 (25/1)
Input #0, mpeg, from 'HARRY_POTTER_GOBLET_OF_FIRE1.vob':
  Duration: 01:15:42.86, start: 0.052000, bitrate: 12699 kb/s
    Stream #0.0[0x1e0]: Video: mpeg2video, yuv420p, 720x576 [PAR 64:45 DAR 16:9], 7500 kb/s, 25 tbr, 90k tbn, 50 tbc
    Stream #0.1[0x80]: Audio: ac3, 48000 Hz, 5.1, s16, 384 kb/s
    Stream #0.2[0x81]: Audio: ac3, 0 channels, s16
Output #0, flv, to 'video2.flv':
    Stream #0.0: Video: flv, yuv420p, 720x416 [PAR 227:221 DAR 10215:5746], q=2-31, 200 kb/s, 90k tbn, 25 tbc
Stream mapping:
  Stream #0.0 -> #0.0
Press [q] to stop encoding
frame= 1501 fps= 98 q=0.0 Lsize=   12920kB time=60.04 bitrate=1762.8kbits/s    
video:12896kB audio:0kB global headers:0kB muxing overhead 0.183273%
FFmpeg version 0.5-svn17737+3:0.svn20090303-1ubuntu4, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --extra-version=svn17737+3:0.svn20090303-1ubuntu4 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --disable-stripping --disable-vhook --enable-libdc1394 --enable-shared --disable-static
  libavutil     49.15. 0 / 49.15. 0
  libavcodec    52.20. 0 / 52.20. 0
  libavformat   52.31. 0 / 52.31. 0
  libavdevice   52. 1. 0 / 52. 1. 0
  libavfilter    0. 4. 0 /  0. 4. 0
  libswscale     0. 7. 1 /  0. 7. 1
  libpostproc   51. 2. 0 / 51. 2. 0
  built on Mar 23 2009 07:13:25, gcc: 4.3.3

Seems stream 0 codec frame rate differs from container frame rate: 50.00 (50/1) -> 25.00 (25/1)
Input #0, mpeg, from 'HARRY_POTTER_GOBLET_OF_FIRE1.vob':
  Duration: 01:15:42.86, start: 0.052000, bitrate: 12699 kb/s
    Stream #0.0[0x1e0]: Video: mpeg2video, yuv420p, 720x576 [PAR 64:45 DAR 16:9], 7500 kb/s, 25 tbr, 90k tbn, 50 tbc
    Stream #0.1[0x80]: Audio: ac3, 48000 Hz, 5.1, s16, 384 kb/s
    Stream #0.2[0x81]: Audio: ac3, 0 channels, s16
Output #0, flv, to 'video3.flv':
    Stream #0.0: Video: flv, yuv420p, 720x416 [PAR 227:221 DAR 10215:5746], q=2-31, 200 kb/s, 90k tbn, 25 tbc
Stream mapping:
  Stream #0.0 -> #0.0
Press [q] to stop encoding
frame= 1501 fps= 99 q=0.0 Lsize=   12920kB time=60.04 bitrate=1762.8kbits/s    
video:12896kB audio:0kB global headers:0kB muxing overhead 0.183273%
FFmpeg version 0.5-svn17737+3:0.svn20090303-1ubuntu4, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --extra-version=svn17737+3:0.svn20090303-1ubuntu4 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --disable-stripping --disable-vhook --enable-libdc1394 --enable-shared --disable-static
  libavutil     49.15. 0 / 49.15. 0
  libavcodec    52.20. 0 / 52.20. 0
  libavformat   52.31. 0 / 52.31. 0
  libavdevice   52. 1. 0 / 52. 1. 0
  libavfilter    0. 4. 0 /  0. 4. 0
  libswscale     0. 7. 1 /  0. 7. 1
  libpostproc   51. 2. 0 / 51. 2. 0
  built on Mar 23 2009 07:13:25, gcc: 4.3.3

Seems stream 0 codec frame rate differs from container frame rate: 50.00 (50/1) -> 25.00 (25/1)
Input #0, mpeg, from 'HARRY_POTTER_GOBLET_OF_FIRE1.vob':
  Duration: 01:15:42.86, start: 0.052000, bitrate: 12699 kb/s
    Stream #0.0[0x1e0]: Video: mpeg2video, yuv420p, 720x576 [PAR 64:45 DAR 16:9], 7500 kb/s, 25 tbr, 90k tbn, 50 tbc
    Stream #0.1[0x80]: Audio: ac3, 48000 Hz, 5.1, s16, 384 kb/s
    Stream #0.2[0x81]: Audio: ac3, 0 channels, s16
Output #0, flv, to 'video4.flv':
    Stream #0.0: Video: flv, yuv420p, 720x416 [PAR 227:221 DAR 10215:5746], q=2-31, 200 kb/s, 90k tbn, 25 tbc
Stream mapping:
  Stream #0.0 -> #0.0
Press [q] to stop encoding
frame= 1501 fps=103 q=0.0 Lsize=   12920kB time=60.04 bitrate=1762.8kbits/s    
video:12896kB audio:0kB global headers:0kB muxing overhead 0.183273%
FFmpeg version 0.5-svn17737+3:0.svn20090303-1ubuntu4, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  configuration: --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --extra-version=svn17737+3:0.svn20090303-1ubuntu4 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --disable-stripping --disable-vhook --enable-libdc1394 --enable-shared --disable-static
  libavutil     49.15. 0 / 49.15. 0
  libavcodec    52.20. 0 / 52.20. 0
  libavformat   52.31. 0 / 52.31. 0
  libavdevice   52. 1. 0 / 52. 1. 0
  libavfilter    0. 4. 0 /  0. 4. 0
  libswscale     0. 7. 1 /  0. 7. 1
  libpostproc   51. 2. 0 / 51. 2. 0
  built on Mar 23 2009 07:13:25, gcc: 4.3.3

Seems stream 0 codec frame rate differs from container frame rate: 50.00 (50/1) -> 25.00 (25/1)
Input #0, mpeg, from 'HARRY_POTTER_GOBLET_OF_FIRE1.vob':
  Duration: 01:15:42.86, start: 0.052000, bitrate: 12699 kb/s
    Stream #0.0[0x1e0]: Video: mpeg2video, yuv420p, 720x576 [PAR 64:45 DAR 16:9], 7500 kb/s, 25 tbr, 90k tbn, 50 tbc
    Stream #0.1[0x80]: Audio: ac3, 48000 Hz, 5.1, s16, 384 kb/s
    Stream #0.2[0x81]: Audio: ac3, 0 channels, s16
Output #0, flv, to 'video5.flv':
    Stream #0.0: Video: flv, yuv420p, 720x416 [PAR 227:221 DAR 10215:5746], q=2-31, 200 kb/s, 90k tbn, 25 tbc
Stream mapping:
  Stream #0.0 -> #0.0
Press [q] to stop encoding
frame= 1501 fps=104 q=0.0 Lsize=   12920kB time=60.04 bitrate=1762.8kbits/s    
video:12896kB audio:0kB global headers:0kB muxing overhead 0.183273%


0 nido at toad:~/ ls -la video[12345].flv
-rw-r--r-- 1 nido nido 13230180 2009-04-02 14:00 video1.flv
-rw-r--r-- 1 nido nido 13230180 2009-04-02 14:00 video2.flv
-rw-r--r-- 1 nido nido 13230180 2009-04-02 14:00 video3.flv
-rw-r--r-- 1 nido nido 13230180 2009-04-02 14:00 video4.flv
-rw-r--r-- 1 nido nido 13230180 2009-04-02 14:01 video5.flv

** Affects: ffmpeg (Ubuntu)
     Importance: Undecided
         Status: New

-- 
using -qscale in ffmpeg doesn't have any effect on coding
https://bugs.launchpad.net/bugs/356322
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