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• opencv Mat convert to AVFrame

  2 août 2014, par Godspped

  I have an image in OpenCV which I can view and save correctly, I want to take this image and pass it to FFMPEG so I can encode it, but when I save the jpg output from ffpmeg I get a empty image, which probably means I am not copying the data correctly over to AVFrame.

  What am I doing wrong...

  Any help is greatly appreciated.

  This is how I set up the final_frame and yuv422 frame

  final_frame = avcodec_alloc_frame();
  
  int num_bytes = avpicture_get_size(PIX_FMT_BGR24, 1600, 720);
  
  final_frame1_buffer = (uint8_t *)av_malloc(num_bytes*sizeof(uint8_t));
  
  avpicture_fill((AVPicture*)final_frame, final_frame1_buffer, PIX_FMT_BGR24, 1600, 720);
  
  
  
  yuv422_final_frame = avcodec_alloc_frame();
  
  int yuv422_num_bytes = avpicture_get_size( PIX_FMT_YUV422P, 1600, 720 );
  
  final_frame2_buffer = (uint8_t *)av_malloc(yuv422_num_bytes*sizeof(uint8_t));
  
  avpicture_fill((AVPicture*)yuv422_final_frame, final_frame2_buffer, PIX_FMT_YUVJ422P, 1600, 720);

  I have attached the code below

  cv::imshow("output image", im3);   <---------- Image shows correctly
  
  cv::Mat rgb_frame;
  
  cv::cvtColor( im3 , rgb_frame, CV_BGR2RGB ) ;
  
  if (final_sws_ctx == NULL)
  
  {
  
      final_sws_ctx = sws_getContext(1600, 720,
  
      AV_PIX_FMT_BGR24, 1600, 720,
  
      AV_PIX_FMT_YUVJ422P, SWS_FAST_BILINEAR, 0, 0, 0);
  
  }
  
  
  
  imwrite( "rgbjpeg.jpg", rgb_frame );  <----- Image Saves correctly here too
  
  
  
  avpicture_fill((AVPicture*)final_frame, rgb_frame.data, PIX_FMT_RGB24, 1600, 720);
  
  sws_scale(final_sws_ctx, final_frame->data, 
  
            final_frame->linesize, 
  
            0, 720, 
  
            yuv422_final_frame->data, 
  
            yuv422_final_frame->linesize);
  
  
  
  AVPacket encode_packet;
  
  int got_output = 0;
  
  av_init_packet(&encode_packet);
  
  encode_packet.data = NULL;
  
  encode_packet.size = 0;
  
  int ret = avcodec_encode_video2(final_codec_context, 
  
                                  &encode_packet, 
  
                                  yuv422_final_frame, 
  
                                  &got_output);
  
  
  
  if (got_output ) {
  
      CString temp;
  
  
  
      temp.Format( "test%u.jpg", counter); 
  
      FILE* outputFile = fopen(temp, "wb");
  
      printf("Write frame (size=%5d)\n", encode_packet.size);
  
      fwrite(encode_packet.data, 1, encode_packet.size, outputFile);
  
      av_free_packet(&encode_packet);
  
      fclose(outputFile);
  
  
  
      counter++;  
  
  }

• Ffmpeg : Audio/Video mixing but no sound

  14 janvier 2014, par user2914878

  I'm trying to add an audio file to a video file generated from images with FFmpeg.

  The command i am using on a Debian distrib is this one

  ffmpeg -r 1 -i edit%0d.jpg outputName.mp4 -i Test.mp3

  The video file is created but the audio is not working .

  Output : :

  > ffmpeg version 0.8.9-6:0.8.9-1, Copyright (c) 2000-2013 the Libav developers
  
    built on Nov  3 2013 00:54:50 with gcc 4.7.2
  
  *** THIS PROGRAM IS DEPRECATED ***
  
  This program is only provided for compatibility and will be removed in a future release. Please use avconv instead.
  
  [image2 @ 0x2283b20] max_analyze_duration reached
  
  Input #0, image2, from 'edit%0d.jpg':
  
    Duration: 00:00:24.00, start: 0.000000, bitrate: N/A
  
      Stream #0.0: Video: mjpeg, yuvj420p, 800x600 [PAR 1:1 DAR 4:3], 1 fps, 1 tbr, 1 tbn, 1 tbc
  
  [mp3 @ 0x22d8840] max_analyze_duration reached
  
  [mp3 @ 0x22d8840] Estimating duration from bitrate, this may be inaccurate
  
  Input #1, mp3, from 'Test.mp3':
  
    Duration: 00:00:46.04, start: 0.000000, bitrate: 128 kb/s
  
      Stream #1.0: Audio: mp3, 16000 Hz, mono, s16, 128 kb/s
  
  [buffer @ 0x2287480] w:800 h:600 pixfmt:yuvj420p
  
  [libx264 @ 0x22d7d20] using SAR=1/1
  
  [libx264 @ 0x22d7d20] using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE4.2 AVX
  
  [libx264 @ 0x22d7d20] profile Main, level 3.1
  
  [libx264 @ 0x22d7d20] 264 - core 123 r2189 35cf912 - H.264/MPEG-4 AVC codec - Copyleft 2003-2012 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=0 b_adapt=1 b_bias=0 direct=1 weightb=0 open_gop=1 weightp=2 keyint=250 keyint_min=1 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.25 aq=1:1.00
  
  Output #0, mp4, to '6953289.mp4':
  
    Metadata:
  
      encoder         : Lavf53.21.1
  
      Stream #0.0: Video: libx264, yuvj420p, 800x600 [PAR 1:1 DAR 4:3], q=-1--1, 1 tbn, 1 tbc
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
  Press ctrl-c to stop encoding
  
  frame=   24 fps= 16 q=17.0 Lsize=    1247kB time=23.00 bitrate= 444.1kbits/s
  
  video:1246kB audio:0kB global headers:0kB muxing overhead 0.079555%
  
  frame I:1     Avg QP:14.91  size: 65650
  
  [libx264 @ 0x22d7d20] frame P:23    Avg QP:14.94  size: 52587
  
  [libx264 @ 0x22d7d20] mb I  I16..4: 11.8%  0.0% 88.2%
  
  [libx264 @ 0x22d7d20] mb P  I16..4: 29.8%  0.0% 60.5%  P16..4:  6.8%  0.2%  0.3%  0.0%  0.0%    skip: 2.4%
  
  [libx264 @ 0x22d7d20] coded y,uvDC,uvAC intra: 73.2% 58.6% 49.7% inter: 9.2% 8.0% 1.2%
  
  [libx264 @ 0x22d7d20] i16 v,h,dc,p: 56% 24%  6% 14%
  
  [libx264 @ 0x22d7d20] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 25% 22% 12%  7%  7%  7%  7%  7%  7%
  
  [libx264 @ 0x22d7d20] i8c dc,h,v,p: 60% 17% 13%  9%
  
  [libx264 @ 0x22d7d20] Weighted P-Frames: Y:17.4% UV:17.4%
  
  [libx264 @ 0x22d7d20] ref P L0: 12.9%  8.0% 66.4% 12.8%
  
  [libx264 @ 0x22d7d20] kb/s:425.05

  On Windows it is working fine, i tried multiple scenarios but i can't seem to find the issue, maybe a codec problem ?

  Thank you !

  Update :

  I manage to fix it this way :

  ffmpeg -r 1 -i edit%0d.jpg -i Test.mp3 -ar 44100 -strict experimental

• How to set FFmpeg decode framerate when decoding audio from microphone ?

  2 septembre 2020, par Sang

  I use FFmpeg to capture audio data from a microphone on Windows. The main code snippet is while(av_read_frame()){/*...*/}. The program will get frames in a default rate, feels about 4 frames per second. But I want to set this rate to 30 frames per second.

  


  I tried this : g_codecCtx->framerate = av_make_q(30, 1);, but it doesn't work. I also use g_codecCtx->sample_rate = 16000; and g_codecCtx->channels = 1; to set the sample rate and the channel, yet I don't know whether it really make sense.

  


  Do you know how to change the rate of reading frames ? Thanks very much.