[FFserver-user] Extract single image from MJPEG stream

[roko]

Hi all

I'm trying to get a single image from an IP Camera MJPEG stream, like this:

ffmpeg -i http://192.168.99.97/video.mjpg -vframes 1 -y algo.jpeg


It works.  But there is a significant delay (between 10 and 20 seconds) getting the frame.  I assume that this time is used to "guess" the right video settings from the source.  I need this to return as soon as possible.  Can someone help me with the right settings for the command line ? thx.


emelo at alfa:~> ffmpeg -i http://192.168.99.97/video.mjpg -vframes 1 -y algo.jpeg 
ffmpeg version 0.11.1 Copyright (c) 2000-2012 the FFmpeg developers
  built on Jun 10 2012 22:43:48 with gcc 4.5.1 20101208 [gcc-4_5-branch revision 167585]
  configuration: --shlibdir=/usr/lib64 --prefix=/usr --mandir=/usr/share/man --libdir=/usr/lib64 --enable-shared --disable-static --enable-debug --disable-stripping --extra-cflags='-fmessage-length=0 -O2 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector -funwind-tables -fasynchronous-unwind-tables -g -fPIC -I/usr/include/gsm' --enable-gpl --enable-x11grab --enable-version3 --enable-pthreads --enable-avfilter --enable-libpulse --enable-libvpx --enable-libmp3lame --enable-libvorbis --enable-libtheora --enable-libspeex --enable-libxvid --enable-libx264 --enable-libschroedinger --enable-libgsm --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-postproc --enable-libdc1394 --enable-librtmp --enable-libfreetype --enable-avresample
  libavutil      51. 54.100 / 51. 54.100
  libavcodec     54. 23.100 / 54. 23.100
  libavformat    54.  6.100 / 54.  6.100
  libavdevice    54.  0.100 / 54.  0.100
  libavfilter     2. 77.100 /  2. 77.100
  libswscale      2.  1.100 /  2.  1.100
  libswresample   0. 15.100 /  0. 15.100
  libpostproc    52.  0.100 / 52.  0.100
<<<<<<<<< HERE IS THE DELAY >>>>>>>>>>
[mjpeg @ 0x62e140] Estimating duration from bitrate, this may be inaccurate
Input #0, mjpeg, from 'http://192.168.99.97/video.mjpg':                        
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: mjpeg, yuvj420p, 640x480 [SAR 1:1 DAR 4:3], 25 fps, 25 tbr, 1200k tbn, 25 tbc
[buffer @ 0x917a20] w:640 h:480 pixfmt:yuvj420p tb:1/1200000 sar:1/1 sws_param:flags=2
[buffersink @ 0x80d680] No opaque field provided
Output #0, image2, to 'algo.jpeg':                                              
  Metadata:
    encoder         : Lavf54.6.100
    Stream #0:0: Video: mjpeg, yuvj420p, 640x480 [SAR 1:1 DAR 4:3], q=2-31, 200 kb/s, 90k tbn, 25 tbc
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg -> mjpeg)
Press [q] to stop, [?] for help
frame=    1 fps=0.0 q=6.4 Lsize=       0kB time=00:00:00.04 bitrate=   0.0kbits/s    
video:36kB audio:0kB global headers:0kB muxing overhead -100.000000%
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