Chris Lasher [EMAIL PROTECTED] added the comment:
michaelni: The muxing overhead now, on numbers reported by FFmpeg, seems
reasonable, and actually very low:
$ ffmpeg -y -f x11grab -s 800x600 -r 20 -i :0.0+0,49 -vcodec mpeg4 -qscale 2 -f
oss -i /dev/dsp -acodec libmp3lame /tmp/out.avi
FFmpeg version SVN-r14282, Copyright (c) 2000-2008 Fabrice Bellard, et al.
configuration: --enable-gpl --enable-x11grab --enable-postproc
--enable-nonfree --enable-avfilter --enable-pthreads --enable-libfaac
--enable-libfaad --enable-liba52 --enable-libx264 --enable-libdc1394
--enable-libgsm --enable-libmp3lame --enable-libxvid --enable-libtheora
--enable-libvorbis
libavutil version: 49.7.0
libavcodec version: 51.60.0
libavformat version: 52.17.0
libavdevice version: 52.0.0
libavfilter version: 0.0.0
built on Jul 18 2008 22:42:37, gcc: 4.2.3 (Ubuntu 4.2.3-2ubuntu7)
[x11grab @ 0x87612d0]device: :0.0+0,49 - display: :0.0 x: 0 y: 49 width: 800
height: 600
[x11grab @ 0x87612d0]shared memory extension found
Input #0, x11grab, from ':0.0+0,49':
Duration: N/A, start: 1216660717.937591, bitrate: 307200 kb/s
Stream #0.0: Video: rawvideo, rgb32, 800x600, 307200 kb/s, 20.00 tb(r)
Input #1, oss, from '/dev/dsp':
Duration: N/A, start: 1216660717.956617, bitrate: N/A
Stream #1.0: Audio: pcm_s16le, 44100 Hz, mono, 705 kb/s
Output #0, avi, to '/tmp/out.avi':
Stream #0.0: Video: mpeg4, yuv420p, 800x600, q=2-31, 200 kb/s, 20.00 tb(c)
Stream #0.1: Audio: libmp3lame, 44100 Hz, mono, 64 kb/s
Stream mapping:
Stream #0.0 - #0.0
Stream #1.0 - #0.1
Press [q] to stop encoding
frame= 83 fps= 19 q=2.0 Lsize=2250kB time=4.15 bitrate=4441.0kbits/s
video:2200kB audio:34kB global headers:0kB muxing overhead 0.702765%
However the problem of poor framerates still applies. Despite FFmpeg reporting a
framerate of 34 fps in the above recording, the actual video appears extremely
choppy. Again, using -an so that no audio is captured, the video appears smooth.
When I use the -vsync 0 option, then I start to believe the framerate reported
during capture, which is really low--5 to 6 FPS.
$ ffmpeg -y -f x11grab -s 800x600 -r 20 -i :0.0+0,49 -vcodec mpeg4 -qscale 2
-vsync 0 -f oss -i /dev/dsp -acodec libmp3lame /tmp/out.avi
FFmpeg version SVN-r14282, Copyright (c) 2000-2008 Fabrice Bellard, et al.
configuration: --enable-gpl --enable-x11grab --enable-postproc
--enable-nonfree --enable-avfilter --enable-pthreads --enable-libfaac
--enable-libfaad --enable-liba52 --enable-libx264 --enable-libdc1394
--enable-libgsm --enable-libmp3lame --enable-libxvid --enable-libtheora
--enable-libvorbis
libavutil version: 49.7.0
libavcodec version: 51.60.0
libavformat version: 52.17.0
libavdevice version: 52.0.0
libavfilter version: 0.0.0
built on Jul 18 2008 22:42:37, gcc: 4.2.3 (Ubuntu 4.2.3-2ubuntu7)
[x11grab @ 0x87612d0]device: :0.0+0,49 - display: :0.0 x: 0 y: 49 width: 800
height: 600
[x11grab @ 0x87612d0]shared memory extension found
Input #0, x11grab, from ':0.0+0,49':
Duration: N/A, start: 1216660853.359198, bitrate: 307200 kb/s
Stream #0.0: Video: rawvideo, rgb32, 800x600, 307200 kb/s, 20.00 tb(r)
Input #1, oss, from '/dev/dsp':
Duration: N/A, start: 1216660853.377797, bitrate: N/A
Stream #1.0: Audio: pcm_s16le, 44100 Hz, mono, 705 kb/s
Output #0, avi, to '/tmp/out.avi':
Stream #0.0: Video: mpeg4, yuv420p, 800x600, q=2-31, 200 kb/s, 20.00 tb(c)
Stream #0.1: Audio: libmp3lame, 44100 Hz, mono, 64 kb/s
Stream mapping:
Stream #0.0 - #0.0
Stream #1.0 - #0.1
Press [q] to stop encoding
frame= 18 fps= 5 q=2.0 Lsize=1727kB time=3.35 bitrate=4222.8kbits/s
video:1685kB audio:28kB global headers:0kB muxing overhead 0.851495%
Capturing a smaller resolution does not help.
$ ffmpeg -y -f x11grab -s 400x300 -r 20 -i :0.0+0,49 -vcodec mpeg4 -qscale 2
-vsync 0 -f oss -i /dev/dsp -acodec libmp3lame /tmp/out.avi
FFmpeg version SVN-r14282, Copyright (c) 2000-2008 Fabrice Bellard, et al.
configuration: --enable-gpl --enable-x11grab --enable-postproc
--enable-nonfree --enable-avfilter --enable-pthreads --enable-libfaac
--enable-libfaad --enable-liba52 --enable-libx264 --enable-libdc1394
--enable-libgsm --enable-libmp3lame --enable-libxvid --enable-libtheora
--enable-libvorbis
libavutil version: 49.7.0
libavcodec version: 51.60.0
libavformat version: 52.17.0
libavdevice version: 52.0.0
libavfilter version: 0.0.0
built on Jul 18 2008 22:42:37, gcc: 4.2.3 (Ubuntu 4.2.3-2ubuntu7)
[x11grab @ 0x87612d0]device: :0.0+0,49 - display: :0.0 x: 0 y: 49 width: 400
height: 300
[x11grab @ 0x87612d0]shared memory extension found
Input #0, x11grab, from ':0.0+0,49':
Duration: N/A, start: 1216661133.627390, bitrate: 76800 kb/s
Stream #0.0: Video: rawvideo, rgb32, 400x300, 76800 kb/s, 20.00 tb(r)
Input #1, oss, from '/dev/dsp':
Duration: N/A, start: 1216661133.640649, bitrate: N/A
Stream #1.0: Audio: pcm_s16le, 44100 Hz, mono, 705 kb/s
Output #0, avi, to '/tmp/out.avi':
Stream
