[FFmpeg-user] Problem using FFMpeg, x11grab, and FFServer

Joel Longanecker joel.longanecker at gmail.com
Wed Jul 30 06:01:15 CEST 2014

Hey guys. Trying an experiment with FFMpeg. The end goal is to serve the
output of an xvfb session over the web and display it on a web page. I
think i've narrowed down my problem to the parameters I am calling ffmpeg

    ffmpegProcess = subprocess.Popen(['ffmpeg',
'-f', 'x11grab',
'-r', '25',
'-s', '640x480',
'-i', ':1.0',
'-pix_fmt', 'yuv420p',
'-preset', 'medium',

and here is my steam that I am trying to serve.

    <Stream live.flv>
Feed feed1.ffm
        Format flv
        VideoCodec libx264

        AVOptionVideo crf 18

        AVOptionVideo preset ultrafast


        VideoSize 640x480

And here are the errors I am getting.

    [tcp @ 0x733b60] TCP connection to localhost:8090 failed: Connection
    Tue Jul 29 22:15:48 2014 - - [GET] "/feed1.ffm HTTP/1.1" 200
    [tcp @ 0x73bbe0] TCP connection to localhost:8090 failed: Connection
    [libx264 @ 0x73e4e0] broken ffmpeg default settings detected
    [libx264 @ 0x73e4e0] use an encoding preset (e.g. -vpre medium)
    [libx264 @ 0x73e4e0] preset usage: -vpre <speed> -vpre <profile>
    [libx264 @ 0x73e4e0] speed presets are listed in x264 --help
    [libx264 @ 0x73e4e0] profile is optional; x264 defaults to high
    Output #0, ffm, to 'http://localhost:8090/feed1.ffm':
        creation_time   : now
        Stream #0:0: Video: h264, yuv444p, 640x480, q=2-31, 128 kb/s, 1000k
tbn, 25 tbc
    Stream mapping:
      Stream #0:0 -> #0:0 (rawvideo -> libx264)
    Error while opening encoder for output stream #0:0 - maybe incorrect
parameters such as bit_rate, rate, width or height

Any help would be greatly appreciated. Thanks!

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