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• X264 encoding using Opencv

  29 novembre 2011, par user573193

  I am working with a high resolution camera : 4008x2672. I a writing a simple program which grabs frame from the camera and sends the frame to a avi file. For working with such a high resolution, I found only x264 codec that could do the trick (Suggestions welcome). I am using opencv for most of the image handling stuff. As mentioned in this post http://doom10.org/index.php?topic=1019.0 , I modified the AVCodecContext members as per ffmpeg presets for libx264 (Had to do this to avoid broken ffmpeg defaults settings error). This is output I am getting when I try to run the program

  libx264 @ 0x992d040]non-strictly-monotonic PTS 
  
  1294846981.526675 1 0 //Timestamp camera_no frame_no
  
  1294846981.621101 1 1
  
  1294846981.715521 1 2
  
  1294846981.809939 1 3
  
  1294846981.904360 1 4
  
  1294846981.998782 1 5
  
  1294846982.093203 1 6
  
      Last message repeated 7 times
  
  [avi @ 0x992beb0]st:0 error, non monotone timestamps 
  
  -614891469123651720 >= -614891469123651720
  
  
  
   OpenCV Error: Unspecified error (Error while writing video frame) in
  
   icv_av_write_frame_FFMPEG, file 
  
  /home/ajoshi/ext/OpenCV-2.2.0/modules/highgui/src/cap_ffmpeg.cpp, line 1034
  
  terminate called after throwing an instance of 'cv::Exception'
  
   what():  /home/ajoshi/ext/OpenCV-2.2.0/modules/highgui/src/cap_ffmpeg.cpp:1034:
  
  error: (-2) Error while writing video frame in function icv_av_write_frame_FFMPEG

  Aborted

  Modifications to the AVCodecContext are :

  if(codec_id == CODEC_ID_H264)
  
  {
  
      //fprintf(stderr, "Trying to parse a preset file for libx264\n");
  
      //Setting Values manually from medium preset
  
      c->me_method = 7;
  
      c->qcompress=0.6;
  
      c->qmin = 10;
  
      c->qmax = 51;
  
      c->max_qdiff = 4;
  
      c->i_quant_factor=0.71;
  
      c->max_b_frames=3;
  
      c->b_frame_strategy = 1;
  
      c->me_range = 16;<br />
  
      c->me_subpel_quality=7;
  
      c->coder_type = 1;
  
      c->scenechange_threshold=40;
  
      c->partitions = X264_PART_I8X8 | X264_PART_I4X4 | X264_PART_P8X8 | X264_PART_B8X8;
  
      c->flags = CODEC_FLAG_LOOP_FILTER;
  
      c->flags2 = CODEC_FLAG2_BPYRAMID | CODEC_FLAG2_MIXED_REFS | CODEC_FLAG2_WPRED | CODEC_FLAG2_8X8DCT | CODEC_FLAG2_FASTPSKIP;
  
      c->keyint_min = 25;
  
      c->refs = 3;
  
      c->trellis=1;
  
      c->directpred = 1;
  
      c->weighted_p_pred=2;
  
  }

  I am probably not setting the dts and pts values which I believed ffmpeg should be setting it for me.

  Any sugggestions welcome.
  Thanks in advance
  

• Revision 7f009975e9 : multi-res : add parameter validity checking Added validity checking in multi-res

  11 juillet 2012, par Yunqing Wang

  Changed Paths : Modify /vp8/vp8_cx_iface.c Modify /vpx/src/vpx_encoder.c multi-res : add parameter validity checking Added validity checking in multi-res encoder. Disable spatial resampling and frame dropping before we have those supports. Also, deallocate the memory for all resolution levels once (...)

• Achieving very poor fps for my iphone app for decode + display h264 frames using ffmpeg and opengl

  29 décembre 2015, par sam18

  I have three steps process for my application which display h264 frame on iPhone screen.

  1. decode using ffmpeg.
  2. scale and colorspace conversion (scale to 256 X 256 Opengl ES 1 texture and convert colospace from yuv420p to rgb565 using sws_Scale from ffmpeg).
  3. Render opengl 1 texture to frame buffer to render buffer

  after these three step process, I got my picture on iPhone screen.

  When I was testing the performance for 720 X 576 resolution frames, I obtain very poor FPS. It is reaching max to 180 milliseconds and hence resulting into 5 to 6 FPS.

  Any direction will be grateful.