[FFmpeg-user] Picture jerky when screencasting?

[belcampo]

On 06/01/11 20:42, lugoteehalt wrote:
> 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.
I don't know what ultimately your intention is, but you're playing 
iplayer, which is 25fps, so grabbing at -r 30, isn't .... AFAIK
You've choosen lossles which results in 1002700kb/s which is an awfull 
lot of data to process.
Your system also has to decode and display the iplayer stuff, don't know 
how taxing that is on your system, but all in all I think it's way too 
much for any system. I'm not 100% sure though.
>
>
> --
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