[MPlayer-users] ffmpeg quality questions

[Yan Seiner]

I am trying to capture a couple of images from a webcam with ffmpeg:

ffmpeg -f video4linux2 -s 512x384 -vframes 2 -i /dev/video0 -sameq -vf 
yadif=1 -f image2 /tmp/test%02d.jpg

The problem is that the images are heavily compressed and lose a lot of 
detail.

Can someone look at the above line and the output below and suggest some 
improvemnts?  In particular, the metadata stream indicates a rate of 200 
kb/sec; that's very little.  Is there some way to increase that?

ffmpeg version 0.8.7, Copyright (c) 2000-2011 the FFmpeg developers
  built on Aug  6 2012 19:12:19 with gcc 4.6.3 20120201 (prerelease)
  configuration: --enable-cross-compile 
--cross-prefix=mips-openwrt-linux-uclibc- --arch=mips --target-os=linux 
--prefix=/usr --enable-shared --enable-static --disable-debug 
--pkg-config=pkg-config --enable-gpl --enable-version3 --disable-asm 
--disable-doc --disable-dxva2 --enable-pthreads --disable-optimizations 
--enable-small --disable-stripping --enable-zlib --disable-outdevs
  libavutil    51.  9. 1 / 51.  9. 1
  libavcodec   53.  8. 0 / 53.  8. 0
  libavformat  53.  5. 0 / 53.  5. 0
  libavdevice  53.  1. 1 / 53.  1. 1
  libavfilter   2. 23. 0 /  2. 23. 0
  libswscale    2.  0. 0 /  2.  0. 0
  libpostproc  51.  2. 0 / 51.  2. 0
[video4linux2 @ 0xa07410] Estimating duration from bitrate, this may be 
inaccurate
Input #0, video4linux2, from '/dev/video0':
  Duration: N/A, start: 1345162532.988122, bitrate: 94277 kb/s
    Stream #0.0: Video: rawvideo, yuyv422, 512x384, 94277 kb/s, 29.97 
tbr, 1000k tbn, 29.97 tbc
Incompatible pixel format 'yuyv422' for codec 'mjpeg', auto-selecting 
format 'yuvj420p'
[buffer @ 0xa01cd0] w:512 h:384 pixfmt:yuyv422 tb:1/1000000 sar:0/1 
sws_param:
[yadif @ 0xa021c0] mode:1 parity:-1
[yadif @ 0xa021c0] auto-inserting filter 'auto-inserted scaler 0' 
between the filter 'src' and the filter 'Parsed filter 0 yadif'
[scale @ 0xa02860] w:512 h:384 fmt:yuyv422 -> w:512 h:384 fmt:yuvj420p 
flags:0x4
Output #0, image2, to '/tmp/test%02d.jpg':
  Metadata:
    encoder         : Lavf53.5.0
    Stream #0.0: Video: mjpeg, yuvj420p, 512x384, q=2-31, 200 kb/s, 90k 
tbn, 29.97 tbc
Stream mapping:
  Stream #0.0 -> #0.0
Press [q] to stop, [?] for help
frame=    2 fps=  0 q=0.0 Lsize=      -0kB time=00:00:00.06 bitrate=  
-2.6kbits/s   
video:7kB audio:0kB global headers:0kB muxing overhead -100.304119%

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