[FFmpeg-user] Picture jerky when screencasting?

[Etienne Buira]

Hi.

On Wed, Jun 01, 2011 at 11:42:25AM -0700, 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!

Not in my libx264-lossless_ultrafast.ffpreset, you should check where
ffmpeg will search for them.
Please try the same with a genuine ffpreset before tweaking.

> [libx264 @ 0x9b558e0] --tune psnr should be used if attempting to benchmark
> psnr!
> [libx264 @ 0x9b558e0] interlace + weightp is not implemented
> FastShuffle Cache64
> [libx264 @ 0x9b558e0] constant rate-factor is incompatible with 2pass.

Ditto * 3

> 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.