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• FFmpeg Libraries : How Do I Convert a Video to 4 Level Grayscale Video at 160x100 Pixels and as Raw Data

  15 avril 2014, par pimathbrainiac

  This seems like an odd question, so I am going to start from the beginning :

  I am a calculator programmer, specifically a Ti-89 programmer, and I'm trying to make a video player for it. I have the code for the calculator side done already, but I need to be able to convert video to a specific format that works as follows :

  Each frame is 4 level grayscale, where there are 2 bytes for every 8 horizontal pixels, a "back," or dark byte, and a "front," or light byte. Basically, every frame is 2 monochrome binary images, with the first byte of the first one is followed by the first byte of the second one, so data is stored as follows :

  FB(front buffer)[1],BB(back buffer)[1],FB[2],BB[2], etc...

  Here's how the display works : (defining 0 as white and 3 as black, with 1 and 2 being in-between shades)
  Each front buffer bit is worth 1, so if the front buffer were displayed with nothing in the back buffer, the "1" (or true) bits would show up as light gray pixels. These are then added to the back buffer bits, which are worth 2 (so if the back buffer were displayed with nothing in the front buffer, the "1" (or true) bits would show up as dark gray pixels) to get :

  "0" bit on either buffer = white pixel (0+0=0)

  "1" bit on front buffer but not back buffer = light gray pixel (1+0=1)

  "1" bit on back buffer but not front buffer = dark gray pixel (0+2=2)

  "1" bit on both buffers = black pixel (1+2=3)

  I have this down calculator-side, but I need to know : 1) How to convert the video to a specific framerate using the libs 2) How to convert these frames to 4-level grayscale at 160x100 pixels and 3) How to save these frames as raw data in the format I described. Thank you in advance for your answer(s).

• FFmpeg stops at once after start streaming

  15 avril 2014, par Byte

  I use FFmpeg like this :

  ffmpeg -i "http://xxx/mpegts" -map 0:2 -map 0:0 -vcodec copy -acodec copy -f flv rtmp://localhost/live/xxx

  At once after start i see this :

  ffmpeg version 0.8.10-4:0.8.10-0ubuntu0.12.04.1, Copyright (c) 2000-2013 the Libav developers
  
  built on Feb  6 2014 20:56:59 with gcc 4.6.3
  
  *** THIS PROGRAM IS DEPRECATED ***
  
  This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
  
  [h264 @ 0xdec460] non-existing PPS referenced
  
  [h264 @ 0xdec460] non-existing PPS 0 referenced
  
  [h264 @ 0xdec460] decode_slice_header error
  
  [h264 @ 0xdec460] no frame!
  
  ... (previous 4 lines repeats 5-6 times)
  
  [mpegts @ 0xde27a0] max_analyze_duration reached
  
  [mpegts @ 0xde27a0] Estimating duration from bitrate, this may be inaccurate
  
  Input #0, mpegts, from 'http://xxx/mpegts':
  
    Duration: N/A, start: 63077.826856, bitrate: 255 kb/s
  
    Program 1 
  
      Stream #0.0[0x44](eng): Audio: aac, 48000 Hz, stereo, s16, 122 kb/s
  
      Stream #0.1[0x45](rus): Audio: aac, 48000 Hz, stereo, s16, 132 kb/s
  
      Stream #0.2[0x46]: Video: h264 (Constrained Baseline), yuv420p, 720x576 [PAR 64:45 DAR 16:9], 26.51 fps, 25 tbr, 90k tbn, 50 tbc
  
  Output #0, flv, to 'rtmp://localhost/live/xxx':
  
    Metadata:
  
      encoder         : Lavf53.21.1
  
      Stream #0.0: Video: [7][0][0][0] / 0x0007, yuv420p, 720x576 [PAR 64:45 DAR 16:9], q=2-31, 1k tbn, 25 tbc
  
      Stream #0.1(eng): Audio: aac, 48000 Hz, stereo, 122 kb/s
  
  Stream mapping:
  
    Stream #0.2 -> #0.0
  
    Stream #0.0 -> #0.1
  
  Press ctrl-c to stop encoding
  
  developer@myhost:

  And it is all. Process stops. In RTMP server i see new connection what at once disconnected.
  What may be wrong ?

  Thanks.

• swscaler warning : deprecated pixel format used

  18 juin 2016, par Martin Delille

  I want to perform a color space conversion of my video frame before converting it to an opengl texture with the following code :

  struct SwsContext * pSwsCtx = sws_getCachedContext(NULL,width, height, codec->pix_fmt, width, height, AV_PIX_FMT_RGBA, SWS_POINT, NULL, NULL, NULL);

  Each time the sws_getCachedContext() function is called I got the following warning :

  [swscaler @ 0x10506fa00] deprecated pixel format used, make sure you did set range correctly

  Here is my ffmpeg output for version information :

  ffmpeg version 2.2 Copyright (c) 2000-2014 the FFmpeg developers
  
    built on Mar 26 2014 15:29:01 with Apple LLVM version 5.1 (clang-503.0.38) (based on LLVM 3.4svn)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/2.2 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-nonfree --enable-hardcoded-tables --enable-avresample --enable-vda --cc=clang --host-cflags= --host-ldflags= --enable-libx264 --enable-libfaac --enable-libmp3lame --enable-libxvid
  
    libavutil      52. 66.100 / 52. 66.100
  
    libavcodec     55. 52.102 / 55. 52.102
  
    libavformat    55. 33.100 / 55. 33.100
  
    libavdevice    55. 10.100 / 55. 10.100
  
    libavfilter     4.  2.100 /  4.  2.100
  
    libavresample   1.  2.  0 /  1.  2.  0
  
    libswscale      2.  5.102 /  2.  5.102
  
    libswresample   0. 18.100 /  0. 18.100
  
    libpostproc    52.  3.100 / 52.  3.100
  
  Hyper fast Audio and Video encoder

  Any idea to disable this warning ? How to set the color range correctly ?