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• How to play sequentially received video clips

  21 novembre 2017, par Ye Li

  I’m working on a prototype project in which some small video clips are sequentially sent over a network. These clips are chunked (using ffmpeg) from a complete video file. Each of the clips is separately playable (containing exactly one GOP). At the destination, I need to smoothly play the sequentially received files as if I were streaming the video, i.e., play the files at the receiver side one by one in one process. May I know whether this is doable ? And if yes, what is the best practice to do this task ?

  The network transmission/receiving parts are written in Python, but I’m open to use any other languages/tools for doing the task.

• X264 Encoder API

  16 avril 2014, par user1884325

  I’m studying the X264 API for encoding images.

  So far I’ve built the X264 library and the following code snippet shows how far I am :

    int frame_size;
  
    x264_t* encoder;
  
    x264_picture_t pic_in, pic_out;
  
    x264_param_t x264Param;
  
    int fps = 20;
  
    int width = 1280;
  
    int height = 720;
  
    x264_nal_t* nals;
  
    int i_nals;
  
  
  
    x264_param_default_preset(&x264Param, "veryfast", "zerolatency");
  
    x264Param.i_threads = 1;
  
    x264Param.i_width = 1280;
  
    x264Param.i_height = 720;
  
    x264Param.i_fps_num = fps;
  
    x264Param.i_fps_den = 1;
  
    x264Param.i_keyint_max = fps;
  
    x264Param.b_intra_refresh = 1;
  
    x264Param.rc.i_rc_method = X264_RC_CRF;
  
    x264Param.rc.f_rf_constant = 25;
  
    x264Param.rc.f_rf_constant_max = 35;
  
    x264Param.b_repeat_headers = 1;
  
    x264Param.b_annexb = 1;
  
    x264_param_apply_profile(&x264Param, "baseline");
  
  
  
    encoder = x264_encoder_open(&x264Param);
  
  
  
    x264_picture_alloc(&pic_in, X264_CSP_BGR, width, height);
  
  
  
    /* How to fill in bitmap data? */
  
  
  
    frame_size = x264_encoder_encode(encoder, &nals, &i_nals, &pic_in, &pic_out);
  
    if (frame_size >= 0)
  
    {
  
        printf("OK\n");
  
    }

  So I’m trying to encode a 24bit BGR bitmap image. However, the x264 header file doesn’t show any API function for writing the bitmap image to the encoder. How is this done ?

  EDIT

  This code snippet seems to work. I would appreciate a review and some comments. Thanks.

    int frame_size;
  
    int accum_frame_size;
  
    x264_t* encoder;
  
    x264_picture_t pic_in, pic_out;
  
    x264_param_t x264Param;
  
    int fps = 20;
  
    int width = 1280;
  
    int height = 720;
  
    x264_nal_t* nals;
  
    int i_nals;
  
    int64_t frameCount = 0;
  
    int k;
  
  
  
    for (k = 0; k < (1280*3*720); k++)
  
    {
  
       bgr[k] = rand();
  
    }
  
  
  
    x264_param_default_preset(&x264Param, "veryfast", "zerolatency");
  
    x264Param.i_threads = 1;
  
    x264Param.i_width = 1280;
  
    x264Param.i_height = 720;
  
    x264Param.i_fps_num = fps;
  
    x264Param.i_fps_den = 1;
  
    x264Param.i_keyint_max = fps;
  
    x264Param.b_intra_refresh = 1;
  
    x264Param.rc.i_rc_method = X264_RC_CRF;
  
    x264Param.i_csp = X264_CSP_BGR;
  
    x264Param.rc.f_rf_constant = 25;
  
    x264Param.rc.f_rf_constant_max = 35;
  
    x264Param.b_repeat_headers = 1;
  
    x264Param.b_annexb = 1;
  
    x264_param_apply_profile(&x264Param, "baseline");
  
  
  
    encoder = x264_encoder_open(&x264Param);
  
  
  
    x264_picture_alloc(&pic_in, X264_CSP_BGR, width, height);
  
  
  
    /* Load 24-bit BGR bitmap */
  
    pic_in.img.i_csp = X264_CSP_BGR;
  
    pic_in.img.i_plane = 1;
  
    pic_in.img.i_stride[0] = 3 * 1280;
  
    pic_in.img.plane[0] = bgr;
  
    pic_in.i_pts = frameCount;
  
    pic_in.i_type = X264_TYPE_AUTO;
  
    pic_out.i_pts = frameCount;
  
  
  
    /* Returns a frame size of 912 for first frame in this case */
  
    frame_size = x264_encoder_encode(encoder, &nals, &i_nals, &pic_in, &pic_out);
  
  
  
    printf("Decoder returned frame size = %d \n", frame_size);
  
    printf("Decoder returned %d NAL units \n", i_nals);
  
    if (frame_size >= 0)
  
    {
  
       int i;
  
       int j;
  
  
  
  
  
       accum_frame_size = 0;
  
       for (i = 0; i < i_nals; i++)
  
       {
  
          printf("******************* NAL %d (%d bytes) *******************\n", i, nals[i].i_payload);
  
          for (j = 0; j < nals[i].i_payload; j++)
  
          {
  
             if (j == 0) printf("First 10 bytes: ");
  
             if (j < 10) printf("%02X |", nals[i].p_payload[j]);
  
             accum_frame_size++;
  
          }
  
          printf("\n");
  
  
  
       }
  
    }
  
  
  
    printf("Verified frame size = %d \n", accum_frame_size);

  EDIT #2
  The encoder outputs this :

       x264 [error]: baseline profile doesn't support 4:4:4
  
       x264 [info]: using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX
  
       x264 [info]: profile High 4:4:4 Predictive, level 3.1, 4:4:4 8-bit
  
       Decoder returned frame size = 1467194
  
       Decoder returned 4 NAL units
  
       ******************* NAL 0 (31 bytes) *******************
  
       First 10 bytes: 00 |00 |00 |01 |67 |F4 |00 |1F |91 |89 |
  
       ******************* NAL 1 (8 bytes) *******************
  
       First 10 bytes: 00 |00 |00 |01 |68 |EF |1F |2C |
  
       ******************* NAL 2 (595 bytes) *******************
  
       First 10 bytes: 00 |00 |01 |06 |05 |FF |FF |4C |DC |45 |
  
       ******************* NAL 3 (1466560 bytes) *******************
  
       First 10 bytes: 00 |00 |01 |65 |88 |82 |0A |FF |F5 |B0 |
  
       Verified frame size = 1467194

  Isn’t each NAL unit supposed to start with 0x00 0x00 0x00 0x01 ?

  szatmary : I appreciate your valuable feedback. So you’re saying that each NAL unit does not necessarily start with 0,0,0,1. However, I’m a bit unclear on your answer. Are you implying that with a certain configuration the NAL units will start with 0,0,0,1 ? If so, which configuration is that ? I need to make sure that each NAL unit I transmit out on the network to a remote receiver starts with 0,0,0,1. Prior to exploring the x264 library I was using the x264 exe and piped BMP data in and encoded data out from the x264 process. I then parsed the encoder output and looked for NAL units by looking for 0,0,0,1. How do I accomplish the same with the x264 library ?

  Regarding libswscale :

  I downloaded the ffmpeg source and ran configure and make in MINGW. After the process had completed I couldn’t find anything but a number of .exe files. How do I build actual static libraries (.lib) which I can use in a Visual Studio project ?

• OpenCV FFmpeg dquant error

  17 septembre 2017, par Karan Maverick

  I am using OpenCV to process video. When trying to process RTSP streamed video I get what appears to be an ffmpeg related error (dquant out of range).

  Is there a way around this ? For example, are there any settings/parameters in opencv’s videoCapture functionality that can be modified to deal with the problem, or perhaps use a different receiver/decoder ?