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• Launching ffmpeg from inside my C code doesn't convert video stream from fifo

  13 mai 2017, par abraxas1

  (Beaglebone Black, ubuntu 16.04 linux 4.4.62-ti-r99)

  I have a raw h264 feed coming into my C program (into a callback from a custom API) and then I named-piped the raw h264 to a file and this CLI command converts that file successfully.

  ffmpeg -report -re -framerate 30 -y -f h264 -i orbi_0148.cam1.h264 -c:v copy -an -video_size 1920x1080 -f mp4 orbi_0148.cam1-1.mp4

  I then try to launch this command from my program with the same options using execv(),

  first mkfifo the fifo’s,

  then launch ffmpeg (shown below) starts the streaming form the cameras to my callback function, and out to the fifos.

  I close the fifos at the end of video recording, and don’t get any file created and get this output, which I don’t understand at all.
  (the successful command line output follows below this output generated from execv())
  thanks, any help much appreciated.
  hardware has come in now and the spot light is on me.

  (execv output with options -report -y -i /tmp/fifocam3.h264 -c:v copy -an -video_size 1920x1080 -f mp4 /media/sd-card/orbi_0140.cam3.mp4)

  root@arm:/home/orbi# cat ffmpeg-20170511-001941.log 
  
  ffmpeg started on 2017-05-11 at 00:19:41
  
  Report written to "ffmpeg-20170511-001941.log"
  
  Command line:
  
  /usr/bin/ffmpeg -report -y -i /tmp/fifocam3.h264 -c:v copy -an -video_size 1920x1080 -f mp4 /media/sd-card/orbi_0140.cam3.mp4
  
  ffmpeg version 2.8.11-0ubuntu0.16.04.1 Copyright (c) 2000-2017 the FFmpeg developers
  
  
  
    built with gcc 5.4.0 (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.4) 20160609
  
    configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/arm-linux-gnueabihf --incdir=/usr/include/arm-linux-gnueabihf --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11gr  libavutil      54. 31.100 / 54. 31.100
  
    libavcodec     56. 60.100 / 56. 60.100
  
    libavformat    56. 40.101 / 56. 40.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 40.101 /  5. 40.101
  
    libavresample   2.  1.  0 /  2.  1.  0
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.101 /  1.  2.101
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Splitting the commandline.
  
  Reading option '-report' ... matched as option 'report' (generate a report) with argument '1'.
  
  Reading option '-y' ... matched as option 'y' (overwrite output files) with argument '1'.
  
  Reading option '-i' ... matched as input url with argument '/tmp/fifocam3.h264'.
  
  Reading option '-c:v' ... matched as option 'c' (codec name) with argument 'copy'.
  
  Reading option '-an' ... matched as option 'an' (disable audio) with argument '1'.
  
  Reading option '-video_size' ... matched as AVOption 'video_size' with argument '1920x1080'.
  
  Reading option '-f' ... matched as option 'f' (force format) with argument 'mp4'.
  
  Reading option '/media/sd-card/orbi_0140.cam3.mp4' ... matched as output url.
  
  Finished splitting the commandline.
  
  Parsing a group of options: global .
  
  Applying option report (generate a report) with argument 1.
  
  Applying option y (overwrite output files) with argument 1.
  
  …
  
  Successfully parsed a group of options.
  
  Parsing a group of options: input url /tmp/fifocam3.h264.
  
  …
  
  Successfully parsed a group of options.
  
  Opening an input file: /tmp/fifocam3.h264.
  
  [h264 @ 0xf249a0] Format h264 probed with size=2048 and score=51
  
  [h264 @ 0xf249a0] Before avformat_find_stream_info() pos: 0 bytes read:32768 seeks:0
  
  [h264 @ 0xf25460] Current profile doesn't provide more RBSP data in PPS, skipping
  
  [h264 @ 0xf25460] bytestream overread -4
  
  [h264 @ 0xf25460] bytestream overread -4
  
  [h264 @ 0xf25460] bytestream overread -4
  
  [h264 @ 0xf25460] bytestream overread -4
  
  [h264 @ 0xf25460] bytestream overread -10
  
  [h264 @ 0xf25460] error while decoding MB 112 28, bytestream -10
  
  [h264 @ 0xf25460] concealing 4737 DC, 4737 AC, 4737 MV errors in P frame
  
  [h264 @ 0xf25460] Frame num gap 7 5
  
  
  
  
  
  /////// successful command line run  \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
  
  root@arm:/home/orbi# ffmpeg -report -re -framerate 30 -y -f h264 -i orbi_0148.cam1.h264 -c:v copy -an -video_size 1920x1080 -f mp4 orbi_0148.cam1-1.mp4
  
  
  
  root@arm:/home/orbi# cat ffmpeg-20170511-002629.log 
  
  ffmpeg started on 2017-05-11 at 00:26:29
  
  Report written to "ffmpeg-20170511-002629.log"
  
  Command line:
  
  ffmpeg -report -re -framerate 30 -y -f h264 -i orbi_0148.cam1.h264 -c:v copy -an -video_size 1920x1080 -f mp4 orbi_0148.cam1-1.mp4
  
  ffmpeg version 2.8.11-0ubuntu0.16.04.1 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with gcc 5.4.0 (Ubuntu/Linaro 5.4.0-6ubuntu1~16.04.4) 20160609
  
    configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/arm-linux-gnueabihf --incdir=/usr/include/arm-linux-gnueabihf --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11gr  libavutil      54. 31.100 / 54. 31.100
  
    libavcodec     56. 60.100 / 56. 60.100
  
    libavformat    56. 40.101 / 56. 40.101
  
    libavdevice    56.  4.100 / 56.  4.100
  
    libavfilter     5. 40.101 /  5. 40.101
  
    libavresample   2.  1.  0 /  2.  1.  0
  
    libswscale      3.  1.101 /  3.  1.101
  
    libswresample   1.  2.101 /  1.  2.101
  
    libpostproc    53.  3.100 / 53.  3.100
  
  Splitting the commandline.
  
  Reading option '-report' ... matched as option 'report' (generate a report) with argument '1'.
  
  Reading option '-re' ... matched as option 're' (read input at native frame rate) with argument '1'.
  
  Reading option '-framerate' ... matched as AVOption 'framerate' with argument '30'.
  
  Reading option '-y' ... matched as option 'y' (overwrite output files) with argument '1'.
  
  Reading option '-f' ... matched as option 'f' (force format) with argument 'h264'.
  
  Reading option '-i' ... matched as input url with argument 'orbi_0148.cam1.h264'.
  
  Reading option '-c:v' ... matched as option 'c' (codec name) with argument 'copy'.
  
  Reading option '-an' ... matched as option 'an' (disable audio) with argument '1'.
  
  Reading option '-video_size' ... matched as AVOption 'video_size' with argument '1920x1080'.
  
  Reading option '-f' ... matched as option 'f' (force format) with argument 'mp4'.
  
  Reading option 'orbi_0148.cam1-1.mp4' ... matched as output url.
  
  Finished splitting the commandline.
  
  Parsing a group of options: global .
  
  Applying option report (generate a report) with argument 1.
  
  Applying option y (overwrite output files) with argument 1.
  
  …
  
  Successfully parsed a group of options.
  
  Parsing a group of options: input url orbi_0148.cam1.h264.
  
  Applying option re (read input at native frame rate) with argument 1.
  
  Applying option f (force format) with argument h264.
  
  …
  
  Successfully parsed a group of options.
  
  Opening an input file: orbi_0148.cam1.h264.
  
  [h264 @ 0x848a20] Before avformat_find_stream_info() pos: 0 bytes read:32768 seeks:0
  
  [h264 @ 0x8515b0] Current profile doesn't provide more RBSP data in PPS, skipping
  
  [h264 @ 0x8515b0] Current profile doesn't provide more RBSP data in PPS, skipping
  
  [h264 @ 0x848a20] max_analyze_duration 5000000 reached at 5005000 microseconds st:0
  
  [h264 @ 0x848a20] After avformat_find_stream_info() pos: 3773440 bytes read:3801088 seeks:0 frames:152
  
  Input #0, h264, from 'orbi_0148.cam1.h264':
  
    Duration: N/A, bitrate: N/A
  
      Stream #0:0, 152, 1/1200000: Video: h264 (Main), yuv420p(tv), 1920x1080, 29.97 fps, 29.97 tbr, 1200k tbn, 59.94 tbc
  
  Successfully opened the file.
  
  Parsing a group of options: output url orbi_0148.cam1-1.mp4.
  
  …
  
  Applying option c:v (codec name) with argument copy.
  
  Applying option an (disable audio) with argument 1.
  
  Applying option f (force format) with argument mp4.
  
  Successfully parsed a group of options.
  
  Opening an output file: orbi_0148.cam1-1.mp4.
  
  Successfully opened the file.
  
  [mp4 @ 0x8fb230] Codec for stream 0 does not use global headers but container format requires global headers
  
  Output #0, mp4, to 'orbi_0148.cam1-1.mp4':
  
    Metadata:
  
      encoder         : Lavf56.40.101
  
      Stream #0:0, 0, 1/1200000: Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 1920x1080, q=2-31, 29.97 fps, 29.97 tbr, 1200k tbn, 1200k tbc
  
  …
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
  Press [q] to stop, [?] for help
  
  [NULL @ 0x8515b0] Current profile doesn't provide more RBSP data in PPS, skipping    
  
  No more output streams to write to, finishing.e=00:00:08.64 bitrate=5887.7kbits/s    
  
  frame=  270 fps= 30 q=-1.0 Lsize=    6443kB time=00:00:08.97 bitrate=5880.6kbits/s    
  
  video:6440kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.056839%
  
  Input file #0 (orbi_0148.cam1.h264):
  
    Input stream #0:0 (video): 270 packets read (6594052 bytes); 
  
    Total: 270 packets (6594052 bytes) demuxed
  
  Output file #0 (orbi_0148.cam1-1.mp4):
  
    Output stream #0:0 (video): 270 packets muxed (6594052 bytes); 
  
    Total: 270 packets (6594052 bytes) muxed
  
  0 frames successfully decoded, 0 decoding errors
  
  [AVIOContext @ 0x931650] Statistics: 34 seeks, 308 writeouts
  
  [AVIOContext @ 0x851190] Statistics: 6594052 bytes read, 0 seeks

• Can't decode h264 frame by frame

  17 mai 2017, par J. Doe

  Here is problematic code :

  int frame_count{0};
  
  int status = -1;
  
  while ((status = av_read_frame(ctx, pkt)) >= 0) {
  
      int got_frame;
  
      auto len =
  
          avcodec_decode_video2(video_ctx, frame, &got_frame, pkt);
  
      errcheck(len);
  
  
  
      if (got_frame == 0)
  
          errthrow("No frame could be decompressed");
  
  
  
      auto w = frame->width;
  
      auto h = frame->height;
  
      auto gray_convert_ctx = sws_getContext(
  
          w, h, input_pix_format, w, h, output_pix_format, SWS_POINT,
  
          nullptr, nullptr, nullptr);
  
  
  
      sws_scale(gray_convert_ctx, frame->data, frame->linesize, 0, h,
  
            frame_converted->data, frame_converted->linesize);
  
  
  
      f_(frame_converted->data[0], frame_converted->linesize[0], w,
  
         h);
  
      ++frame_count;
  
      sws_freeContext(gray_convert_ctx);
  
  
  
      if (pkt->data) {
  
          pkt->size -= len;
  
          pkt->data += len;
  
      }
  
  }
  
  if (status != AVERROR_EOF)
  
      errcheck(status);

  With vp8/vp9 all is okay, but when I’m trying to decode h264, I’ve got error :

  ➤ ./cv /tmp/x
  
  file size: 694KiB
  
  read /tmp/x: 694KiB
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x191fc00] Format mov,mp4,m4a,3gp,3g2,mj2 probed with size=2048 and score=100
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x191fc00] ISO: File Type Major Brand: mp42
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x191fc00] rfps: 31.000000 0.000599
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x191fc00] Before avformat_find_stream_info() pos: 3104 bytes read:32768 seeks:0
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x191fc00] All info found
  
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x191fc00] After avformat_find_stream_info() pos: 456697 bytes read:458752 seeks:0 frames:34
  
  [h264 @ 0x1926700] no frame!
  
  error: AV: Invalid data found when processing input

  Maybe that’s because of h264 does not support AV_CODEC_CAP_TRUNCATED ? But I suppose it’s should be handled in av_read_frame.

  Then ignoring (just skipping this read if error occurs) — no frame decoded anyway until EOF. :c This video working fine with ffplay/mpv/etc. and was recorded by Android.

  #include <iostream>
  
  
  
  extern "C" {
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  }
  
  
  
  #include <functional>
  
  
  
  class Video
  
  {
  
        public:
  
      static std::string TAG;
  
  
  
      Video();
  
      Video(void *data_ptr, size_t data_size);
  
      ~Video();
  
  
  
      void set(void *data_ptr, size_t data_size);
  
      void process(std::function f_);
  
  
  
        private:
  
      static constexpr AVPixelFormat output_pix_format{AV_PIX_FMT_GRAY8};
  
  
  
      struct {
  
          uint8_t *ptr{nullptr};
  
          size_t size;
  
      } bd;
  
  
  
      bool video_ctx_opened{false};
  
      AVCodecContext *video_ctx{nullptr};
  
      AVStream *video_stream{nullptr};
  
  
  
      size_t width;
  
      size_t heigh;
  
  
  
      AVPixelFormat input_pix_format;
  
  
  
      size_t avio_ctx_buffer_size = 32 * 1024; // 32 KiB
  
      uint8_t *avio_ctx_buffer{nullptr};
  
  
  
      AVFormatContext *ctx{nullptr};
  
      AVIOContext *avio_ctx{nullptr};
  
  
  
      uint8_t *frame_converted_buffer{nullptr};
  
      AVFrame *frame_converted{nullptr};
  
  
  
      AVFrame *frame{nullptr};
  
      AVPacket *pkt{nullptr};
  
  
  
      void init_stream();
  
      void init_codec();
  
      void init_frame_converted();
  
  };
  
  
  
  
  
  extern "C" {
  
  #include <libswscale></libswscale>swscale.h>
  
  }
  
  
  
  #include <iostream>
  
  #include <stdexcept>
  
  
  
  namespace
  
  {
  
  using str_t = decltype(Video::TAG);
  
  
  
  static str_t averr(int code)
  
  {
  
      static thread_local std::array buf;
  
      av_make_error_string(buf.data(), buf.size(), code);
  
      return str_t(buf.data(), buf.size());
  
  }
  
  
  
  static str_t errstr(int err) { return Video::TAG + ": " + averr(err); }
  
  
  
  static str_t errstr(const char *err) { return Video::TAG + ": " + err; }
  
  
  
  static void errthrow(str_t err) { throw std::runtime_error{std::move(err)}; }
  
  
  
  static void errcheck(int val)
  
  {
  
      if (val &lt; 0)
  
          errthrow(errstr(val));
  
  }
  
  
  
  template <class t="t"> static void errcheck(T *ptr, const char *errmsg)
  
  {
  
      if (!ptr)
  
          errthrow(errstr(errmsg));
  
  }
  
  
  
  static int read_packet(void *opaque, uint8_t *buf, int buf_size)
  
  {
  
      struct _bd {
  
          uint8_t *ptr;
  
          size_t size;
  
      };
  
      _bd *bd = static_cast&lt;_bd *>(opaque);
  
  
  
      buf_size = FFMIN(buf_size, bd->size);
  
  
  
      memcpy(buf, bd->ptr, buf_size);
  
      bd->ptr += buf_size;
  
      bd->size -= buf_size;
  
  
  
      return buf_size;
  
  }
  
  }
  
  
  
  std::string Video::TAG = "AV";
  
  
  
  Video::Video()
  
  {
  
      av_register_all();
  
      avcodec_register_all();
  
  
  
      frame = av_frame_alloc();
  
      errcheck(frame, "Could not allocate frame");
  
  
  
      pkt = static_cast<avpacket>(av_malloc(sizeof(AVPacket)));
  
      errcheck(pkt, "Could not allocate packet");
  
      av_init_packet(pkt);
  
  }
  
  
  
  Video::Video(void *data_ptr, size_t data_size) : Video()
  
  {
  
      set(data_ptr, data_size);
  
  }
  
  
  
  Video::~Video()
  
  {
  
      avformat_close_input(&amp;ctx);
  
      if (avio_ctx) {
  
          av_freep(&amp;avio_ctx->buffer);
  
          av_freep(&amp;avio_ctx);
  
      }
  
  
  
      if (video_ctx) {
  
          avcodec_close(video_ctx);
  
          av_free(video_ctx);
  
      }
  
      if (frame)
  
          av_frame_free(&amp;frame);
  
      if (frame_converted_buffer)
  
          av_freep(&amp;frame_converted_buffer);
  
      if (frame_converted)
  
          av_frame_free(&amp;frame_converted);
  
      if (pkt) {
  
          av_free_packet(pkt);
  
          av_free(pkt);
  
      }
  
  }
  
  
  
  void Video::set(void *data_ptr, size_t data_size)
  
  {
  
      bd.ptr = static_cast(data_ptr);
  
      bd.size = data_size;
  
  
  
      init_stream();
  
      init_frame_converted();
  
      init_codec();
  
      pkt->data = nullptr;
  
      pkt->size = 0;
  
  }
  
  
  
  void Video::process(
  
      std::function f_)
  
  {
  
      int frame_count{0};
  
      int status = -1;
  
      while ((status = av_read_frame(ctx, pkt)) >= 0) {
  
          int got_frame;
  
          auto len =
  
              avcodec_decode_video2(video_ctx, frame, &amp;got_frame, pkt);
  
          errcheck(len);
  
  
  
          if (got_frame == 0)
  
              errthrow("No frame could be decompressed");
  
  
  
          auto w = frame->width;
  
          auto h = frame->height;
  
          auto gray_convert_ctx = sws_getContext(
  
              w, h, input_pix_format, w, h, output_pix_format, SWS_POINT,
  
              nullptr, nullptr, nullptr);
  
  
  
          sws_scale(gray_convert_ctx, frame->data, frame->linesize, 0, h,
  
                    frame_converted->data, frame_converted->linesize);
  
  
  
          f_(frame_converted->data[0], frame_converted->linesize[0], w,
  
             h);
  
          ++frame_count;
  
          sws_freeContext(gray_convert_ctx);
  
  
  
          if (pkt->data) {
  
              pkt->size -= len;
  
              pkt->data += len;
  
          }
  
      }
  
      if (status != AVERROR_EOF)
  
          errcheck(status);
  
  }
  
  
  
  void Video::init_stream()
  
  {
  
      ctx = avformat_alloc_context();
  
      errcheck(ctx, "Could not allocate format context");
  
  
  
      avio_ctx_buffer =
  
          static_cast(av_malloc(avio_ctx_buffer_size));
  
      errcheck(avio_ctx_buffer, "Could not allocate io buffer");
  
  
  
      avio_ctx = avio_alloc_context(avio_ctx_buffer, avio_ctx_buffer_size, 0,
  
                                    &amp;bd, &amp;read_packet, nullptr, nullptr);
  
      errcheck(avio_ctx, "Could not allocate io context");
  
      ctx->pb = avio_ctx;
  
  
  
      auto status = avformat_open_input(&amp;ctx, nullptr, nullptr, nullptr);
  
      errcheck(status);
  
  
  
      status = avformat_find_stream_info(ctx, nullptr);
  
      errcheck(status);
  
  
  
      for (decltype(ctx->nb_streams) i = 0; i &lt; ctx->nb_streams; ++i) {
  
          auto stream = ctx->streams[i];
  
          if (!stream || !stream->codec)
  
              continue;
  
          if (stream->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
  
              video_stream = stream;
  
              break;
  
          }
  
      }
  
      errcheck(video_stream, "Could not find valid video stream");
  
  
  
      width = video_stream->codec->width;
  
      heigh = video_stream->codec->height;
  
  
  
      input_pix_format = video_stream->codec->pix_fmt;
  
  }
  
  
  
  void Video::init_codec()
  
  {
  
      auto codec = avcodec_find_decoder(video_stream->codec->codec_id);
  
      errcheck(codec, "Codec not found");
  
  
  
      video_ctx = avcodec_alloc_context3(codec);
  
      errcheck(video_ctx, "Could not allocate video codec context");
  
  
  
      if (codec->capabilities &amp; AV_CODEC_CAP_TRUNCATED)
  
          video_ctx->flags |=
  
              AV_CODEC_FLAG_TRUNCATED; // we do not send complete frames
  
  
  
      auto status = avcodec_open2(video_ctx, codec, nullptr);
  
      errcheck(status);
  
  }
  
  
  
  void Video::init_frame_converted()
  
  {
  
      frame_converted = av_frame_alloc();
  
      errcheck(frame_converted, "Could not allocate frame");
  
  
  
      int frame_converted_buffer_size =
  
          avpicture_get_size(output_pix_format, width, heigh);
  
      errcheck(frame_converted_buffer_size);
  
  
  
      frame_converted_buffer =
  
          static_cast(av_malloc(frame_converted_buffer_size));
  
      errcheck(frame_converted_buffer, "Could not allocate picture buffer");
  
  
  
      auto status = avpicture_fill(
  
          reinterpret_cast<avpicture>(frame_converted),
  
          frame_converted_buffer, output_pix_format, width, heigh);
  
      errcheck(status);
  
  }
  
  
  
  #include <vector>
  
  #include <fstream>
  
  
  
  std::vector<char> read_file(const std::string &amp;fname)
  
  {
  
      std::ifstream file(fname, std::ios::binary | std::ios::ate);
  
      if (!file.is_open())
  
          throw std::runtime_error{"can't open " + fname};
  
  
  
      auto size = file.tellg();
  
      file.seekg(0, std::ios::beg);
  
  
  
      std::cout &lt;&lt; "file size: " &lt;&lt; std::to_string(size / 1024) &lt;&lt; "KiB\n";
  
  
  
      std::vector<char> buffer(size);
  
  
  
      if (file.read(buffer.data(), size))
  
          return buffer;
  
      return {};
  
  }
  
  
  
  int main(int argc, const char **argv)
  
  {
  
      if (argc &lt; 2)
  
          return EXIT_FAILURE;
  
  
  
      av_log_set_level(AV_LOG_DEBUG);
  
  
  
      try {
  
          auto data = read_file(argv[1]);
  
          std::cout &lt;&lt; "read " &lt;&lt; argv[1] &lt;&lt; ": "
  
                    &lt;&lt; std::to_string(data.size() / 1024) &lt;&lt; "KiB\n";
  
  
  
                  Video v;
  
              v.set(data.data(), data.size());
  
  
  
              v.process([](unsigned char *data, int wrap, int xsize,
  
                             int ysize) {
  
                  std::cout &lt;&lt; "w: " &lt;&lt; xsize
  
                            &lt;&lt; " h: " &lt;&lt; ysize &lt;&lt; '\n';
  
              });
  
  
  
      } catch (const std::runtime_error &amp;e) {
  
          std::cout &lt;&lt; "error: " &lt;&lt; e.what() &lt;&lt; '\n';
  
      }
  
  }
  
  </char></char></fstream></vector></avpicture></avpacket></class></stdexcept></iostream></functional></iostream>

  Compile&Run :
  g++ cv.cpp -std=c++14 -lavutil -lavcodec -lavformat -lswscale ; ./a.out file.name.here

• Anomalie #3664 : Insertion de formulaire dans l’editeur et champ obligatoire en HTML5

  19 juin 2017, par b b

  Il semblerait que ça se confirme, cf le mail de jean marie sur spip-zone : https://www.mail-archive.com/spip-zone@rezo.net/msg43765.html