[FFmpeg-user] Picture jerky when screencasting?

[lugoteehalt]

As beginner trying to use ffmpeg to record screen, screencasting.  Problem is
the recorded picture jerks - as though only every 4th. frame, say, is being
recorded. This recording, say, BBC iplayer at full screen. 

ffmpeg -f alsa -ac 2 -i pulse -f x11grab -s `xdpyinfo | grep 'dimensions:'|
awk '{print $2}'` -r 25 -i :0.0 -sameq out.mpg

Tried this:

ffmpeg -f alsa -ac 2 -i pulse -f x11grab -r 30 -s 1360x768 -i :0.0 -acodec
pcm_s16le -vcodec libx264 -vpre lossless_ultrafast output.mkv
ffmpeg version git-N-30155-g01a73d6, Copyright (c) 2000-2011 the FFmpeg
developers
  built on May 23 2011 22:32:40 with gcc 4.4.5
  configuration: --enable-gpl --enable-version3 --enable-nonfree
--enable-postproc --enable-libfaac --enable-libmp3lame
--enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora
--enable-libvorbis --enable-libx264 --enable-libxvid --enable-x11grab
  libavutil    51.  2. 1 / 51.  2. 1
  libavcodec   53.  6. 0 / 53.  6. 0
  libavformat  53.  2. 0 / 53.  2. 0
  libavdevice  53.  0. 0 / 53.  0. 0
  libavfilter   2. 10. 0 /  2. 10. 0
  libswscale    0. 14. 0 /  0. 14. 0
  libpostproc  51.  2. 0 / 51.  2. 0
[alsa @ 0x9b5cb40] capture with some ALSA plugins, especially dsnoop, may
hang.
[alsa @ 0x9b5cb40] Estimating duration from bitrate, this may be inaccurate
Input #0, alsa, from 'pulse':
  Duration: N/A, start: 1306952159.991708, bitrate: N/A
    Stream #0.0: Audio: pcm_s16le, 44100 Hz, 2 channels, s16, 1411 kb/s
[x11grab @ 0x9b6ec00] device: :0.0 -> display: :0.0 x: 0 y: 0 width: 1360
height: 768
[x11grab @ 0x9b6ec00] shared memory extension found
[x11grab @ 0x9b6ec00] Estimating duration from bitrate, this may be
inaccurate
Input #1, x11grab, from ':0.0':
  Duration: N/A, start: 1306952160.163753, bitrate: 1002700 kb/s
    Stream #1.0: Video: rawvideo, bgra, 1360x768, 1002700 kb/s, 30 tbr,
1000k tbn, 30 tbc
Incompatible pixel format 'bgra' for codec 'libx264', auto-selecting format
'yuv420p'
[buffer @ 0x9b5e680] w:1360 h:768 pixfmt:bgra tb:1/1000000 sar:0/1
sws_param:
[ffsink @ 0x9b5d520] auto-inserting filter 'auto-inserted scaler 0' between
the filter 'src' and the filter 'out'
[scale @ 0x9b5dee0] w:1360 h:768 fmt:bgra -> w:1360 h:768 fmt:yuv420p
flags:0xa0000004
[libx264 @ 0x9b558e0] --psnr used with psy on: results will be invalid!
[libx264 @ 0x9b558e0] --tune psnr should be used if attempting to benchmark
psnr!
[libx264 @ 0x9b558e0] interlace + weightp is not implemented
[libx264 @ 0x9b558e0] using cpu capabilities: MMX2 SSE2Fast SSSE3
FastShuffle Cache64
[libx264 @ 0x9b558e0] constant rate-factor is incompatible with 2pass.
Output #0, matroska, to 'output.mkv':
    Stream #0.0: Video: libx264, yuv420p, 1360x768, q=0-69, pass 1, pass 2,
200 kb/s, 90k tbn, 30 tbc
    Stream #0.1: Audio: pcm_s16le, 44100 Hz, 2 channels, s16, pass 1, pass
2, 1411 kb/s
Stream mapping:
  Stream #1.0 -> #0.0
  Stream #0.0 -> #0.1
Error while opening encoder for output stream #0.0 - maybe incorrect
parameters such as bit_rate, rate, width or height

Any suggestions?  'constant rate-factor in incompatible with 2pass' is in
red.  Thanks any help.


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