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• Programmatically creating a video using FFmpeg, using SDL's sprite screenshot BMP

  28 octobre 2016, par alok

  I have an animation/sprite developed in C++ on SDL2 libs (based on this answer). The bitmaps are saved to a certain path. They are of dimensions 640x480 and format is given by the SDL constant SDL_PIXELFORMAT_ARGB8888.

  I have a second program written in C on top of FFmpeg libs, which reads one image from the above path (just one for the time being, will read the whole series when it works for just one).
  This does the following (in gist - skipping validation & comments for conciseness)

  AVCodec *codec;
  
  AVCodecContext *c = NULL;
  
  int i, ret, x, y, got_output;
  
  FILE *f;
  
  AVFrame *frame;
  
  AVPacket pkt;
  
  uint8_t endcode[] = { 0, 0, 1, 0xb7 };
  
  
  
  codec = avcodec_find_encoder(codec_id);
  
  c = avcodec_alloc_context3(codec);
  
  c->bit_rate = 400000;
  
  /* resolution must be a multiple of two */
  
  c->width = 640;
  
  c->height = 480;
  
  c->time_base = (AVRational ) { 1, 25 };
  
  c->gop_size = 5;
  
  c->max_b_frames = 1;
  
  c->pix_fmt = AV_PIX_FMT_YUV420P;
  
  
  
  av_opt_set(c->priv_data, "preset", "slow", 0);
  
  avcodec_open2(c, codec, NULL);
  
  
  
  fopen(filename, "wb");
  
  frame = av_frame_alloc();
  
  av_image_alloc(frame->data, frame->linesize, c->width, c->height, c->pix_fmt, 32);
  
  
  
  for (i = 0; i < 25; ++i) {
  
      readSingleFile("/tmp/alok1/ss099.bmp", &frame->data);//Read the saved BMP into frame->data
  
      frame->pts = i;
  
      frame->width = 640;
  
      frame->height = 480;
  
      frame->format = -1;
  
  
  
      av_init_packet(&pkt);
  
      pkt.data = NULL; // packet data will be allocated by the encoder
  
      pkt.size = 0;
  
      ret = avcodec_encode_video2(c, &pkt, frame, &got_output);
  
  
  
  
  
      if (got_output) {
  
          printf("Write frame %3d (size=%5d)\n", i, pkt.size);
  
          fwrite(pkt.data, 1, pkt.size, f);
  
      }
  
      av_packet_unref(&pkt);
  
  }
  
  for (got_output = 1; got_output; i++) {
  
      fflush(stdout);
  
  
  
      ret = avcodec_encode_video2(c, &pkt, NULL, &got_output);
  
      if (ret < 0) {
  
          fprintf(stderr, "Error encoding frame\n");
  
          exit(1);
  
      }
  
  
  
      if (got_output) {
  
          printf("[DELAYED]Write frame %3d (size=%5d)\n", i, pkt.size);
  
          fwrite(pkt.data, 1, pkt.size, f);
  
          av_packet_unref(&pkt);
  
      }
  
  }
  
  
  
  fwrite(endcode, 1, sizeof(endcode), f);
  
  //cleanup

  As a result of the above code(which compiles without trouble), I can get a video which plays for 1 second - this part is working as expected. Problem is that the image seen is a green full screen like below.

  The image that is being read using the readSingleImage(...) function is rendered by image viewer(linux, gwenview and okular) as follows :

  Any pointers as to what could be going wrong ?

• ffmpeg livestream only shows one frame at a time

  28 octobre 2016, par user3308335

  So, I’ve tried to turn one of my pis into a silly "baby cam" for my pet and I followed the tutorial made by Ustream.tv on how to do this.

  This is the script I run to start the stream :

  #!/bin/bash
  
  RTMP_URL=<rtmpurl>
  
  STREAM_KEY=<streamkey>
  
  while :
  
  do
  
    raspivid -n -hf -t 0 -w 640 -h 480 -fps 15 -b 400000 -o - | ffmpeg -i - -vcodec copy -an  -f flv $RTMP_URL/$STREAM_KEY
  
    sleep 2
  
  done
  
  </streamkey></rtmpurl>

  However, whenever I go to view the stream, the stream shows only one frame. The same frame until I refresh the browser, watch the ad again, and then it’s a new same frame that it’ll show.

  Does anyone have an idea why this might be happening or any troubleshooting tricks for me to try ?

• Videojs does not play converted mp4 file

  4 février 2017, par Chris Palmer Breuer

  I am creating a platform for video files to be uploaded to. In order for them to get played through Videojs, I convert/demux mkv/flv/3gp files to mp4 files.

  The issue I encounter is that if I demux such video/mkv file, I get the error message Video format or mime type not supported, even though it is a "working" mp4 file on my computer.

  I think I understand that mkv files are containers, and that if demuxed it keeps the same video and audio codec and if that is not supported by Videojs/HTML5 the video cannot get played. Please, correct me if I am wrong.

  Can anyone please tell me why this demux of mkv.mkv to mkv.mp4 will not play in my browser ?

  ➜  ~ ffmpeg -i mkv.mkv -vcodec copy -acodec copy mkv.mp4
  
  ffmpeg version 3.2.2 Copyright (c) 2000-2016 the FFmpeg developers
  
    built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/3.2.2 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --disable-lzma --enable-vda
  
    libavutil      55. 34.100 / 55. 34.100
  
    libavcodec     57. 64.101 / 57. 64.101
  
    libavformat    57. 56.100 / 57. 56.100
  
    libavdevice    57.  1.100 / 57.  1.100
  
    libavfilter     6. 65.100 /  6. 65.100
  
    libavresample   3.  1.  0 /  3.  1.  0
  
    libswscale      4.  2.100 /  4.  2.100
  
    libswresample   2.  3.100 /  2.  3.100
  
    libpostproc    54.  1.100 / 54.  1.100
  
  Input #0, matroska,webm, from 'mkv.mkv':
  
    Metadata:
  
      ENCODER         : Lavf53.24.2
  
    Duration: 00:00:34.08, start: -1.400000, bitrate: 1232 kb/s
  
      Stream #0:0: Video: mpeg4 (Simple Profile), yuv420p, 720x480 [SAR 1:1 DAR 3:2], 25 fps, 25 tbr, 1k tbn, 25 tbc (default)
  
      Stream #0:1: Audio: aac (LC), 48000 Hz, 5.1, fltp (default)
  
  Output #0, mp4, to 'mkv.mp4':
  
    Metadata:
  
      encoder         : Lavf57.56.100
  
      Stream #0:0: Video: mpeg4 (Simple Profile) ( [0][0][0] / 0x0020), yuv420p, 720x480 [SAR 1:1 DAR 3:2], q=2-31, 25 fps, 25 tbr, 16k tbn, 1k tbc (default)
  
      Stream #0:1: Audio: aac (LC) ([64][0][0][0] / 0x0040), 48000 Hz, 5.1 (default)
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:1 -> #0:1 (copy)
  
  Press [q] to stop, [?] for help
  
  frame=  887 fps=0.0 q=-1.0 Lsize=    5130kB time=00:00:35.45 bitrate=1185.4kbits/s speed= 668x
  
  video:3447kB audio:1663kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.401607%

  Thanks for all the help already. I cant seem to find an answer...