title: Capture Android screen as a video file using FFmpeg
body: <p>I am trying to capture an Android device's screen as a video file using FFmpeg with this command: </p>
  
  <pre><code>/data/local/ffmpeg -y -vcodec rawvideo -f rawvideo -pix_fmt rgb32 -s 320x480 -i /dev/graphics/fb0 /sdcard/output2.avi 2&gt; /sdcard/out.txt
  </code></pre>
  
  <p>This creates a file with a single (unclear) frame and stops. </p>
  
  <pre><code>ffmpeg version 0.11.1 Copyright (c) 2000-2012 the FFmpeg developers
    built on Sep 20 2012 13:28:38 with gcc 4.6.x-google 20120106 (prerelease)
    configuration: --arch=arm --cpu=cortex-a8 --target-os=linux --enable-runtime-cpudetect --prefix=/data/data/org.witness.sscvideoproto --enable-pic --disable-shared --enable-static --cross-prefix=/opt/android-ndk/toolchains/arm-linux-androideabi-4.6/prebuilt/linux-x86/bin/arm-linux-androideabi- --sysroot=/opt/android-ndk/platforms/android-3/arch-arm --extra-cflags='-I../x264 -mfloat-abi=softfp -mfpu=neon' --extra-ldflags=-L../x264 --enable-version3 --enable-gpl --disable-doc --enable-yasm --enable-decoders --enable-encoders --enable-muxers --enable-demuxers --enable-parsers --enable-protocols --enable-filters --enable-avresample --enable-libfreetype --disable-indevs --enable-indev=lavfi --disable-outdevs --enable-hwaccels --enable-ffmpeg --disable-ffplay --disable-ffprobe --disable-ffserver --disable-network --enable-libx264 --enable-zlib
    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
  [rawvideo @ 0xee5540] Estimating duration from bitrate, this may be inaccurate
  Input #0, rawvideo, from '/dev/graphics/fb0':
    Duration: N/A, start: 0.000000, bitrate: N/A
      Stream #0:0: Video: rawvideo (BGRA / 0x41524742), bgra, 320x480, 25 tbr, 25 tbn, 25 tbc
  [buffer @ 0xef16e0] w:320 h:480 pixfmt:bgra tb:1/25 sar:0/1 sws_param:flags=2
  [buffersink @ 0xef1950] No opaque field provided
  [format @ 0xef1a70] auto-inserting filter 'auto-inserted scaler 0' between the filter 'src' and the filter 'format'
  [scale @ 0xef2c10] w:320 h:480 fmt:bgra sar:0/1 -&gt; w:320 h:480 fmt:yuv420p sar:0/1 flags:0x4
  Output #0, avi, to '/sdcard/output2.avi':
    Metadata:
      ISFT            : Lavf54.6.100
      Stream #0:0: Video: mpeg4 (FMP4 / 0x34504D46), yuv420p, 320x480, q=2-31, 200 kb/s, 25 tbn, 25 tbc
  Stream mapping:
    Stream #0:0 -&gt; #0:0 (rawvideo -&gt; mpeg4)
  Press [q] to stop, [?] for help
  frame=    5 fps=0.0 q=5.4 Lsize=     199kB time=00:00:00.20 bitrate=8156.6kbits/s    
  video:193kB audio:0kB global headers:0kB muxing overhead 2.929166%
  </code></pre>
  
  <p>Any idea what am I doing wrong?</p>