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• FFMPEG exception in debug mode only

  28 septembre 2015, par Ahmed-Anas

  So I’m trying to use ffmpeg in c++. My code is like this :

  #include <iostream>
  
  
  
  extern "C"
  
  {
  
  #include "libavcodec\avcodec.h"
  
  #include "libavformat\avformat.h"
  
  #include "libswscale\swscale.h"
  
  
  
  }
  
  
  
  using namespace std;
  
  #pragma comment(lib, "dev/lib/avcodec.lib")
  
  #pragma comment(lib, "dev/lib/avformat.lib")
  
  #pragma comment(lib, "dev/lib/swscale.lib")
  
  
  
  int main()
  
  {
  
      avcodec_register_all();
  
      av_register_all();
  
      char inputFile[] = "video.mp4";
  
      AVFormatContext *pFormatCtx;
  
  
  
      if (avformat_open_input(&amp;pFormatCtx, inputFile, NULL, 0) != 0) // exception occurs here
  
      {
  
          cout &lt;&lt; "could not open file"; 
  
          return -1;
  
      }
  
  
  
  }
  
  </iostream>

  This code runs in release mode but in debug mode I get the exception at avformat_open_input :

  Unhandled exception at 0x0000000074BC3C35 (avformat-55.dll) in
  ingrain.exe : 0xC0000005 : Access violation reading location
  0xFFFFFFFFFFFFFFFF.

  I downloaded the dll’s and lib’s directely from ffmpeg’s site and included them in my visual studio 2012’s project.

  Thank’s in advance.

• How to stop os.system() in Python ?

  30 septembre 2015, par 吴雨羲

  I want to stop the cmd command after 12 seconds. How to stop it ? My program doesn’t work.

  import multiprocessing
  
  import os
  
  import time
  
  
  
  
  
  def process():
  
      os.system('ffmpeg -i rtsp://218.204.223.237:554/live/1/66251FC11353191F/e7ooqwcfbqjoo80j.sdp -c copy dump.mp4')
  
  
  
  
  
  def stop():
  
      time.sleep(12)
  
  
  
  
  
  if __name__ == '__main__':
  
      p = multiprocessing.Process(target=process, args=())
  
      s = multiprocessing.Process(target=stop, args=())
  
      p.start()
  
      s.start()
  
      s.join()
  
      p.terminate()

  I change my program follow Pedro’s suggusetion @Pedro Lobito ,but it still doesn`t work.

  import shlex
  
  
  
  import subprocess
  
  import time
  
  
  
  command_line = 'ffmpeg -i rtsp://218.204.223.237:554/live/1/66251FC11353191F/e7ooqwcfbqjoo80j.sdp -c copy dump.mp4'
  
  
  
  proc = subprocess.Popen(shlex.split(command_line), shell=True)
  
  print '1' * 50
  
  time.sleep(2)  # <-- sleep for 12''
  
  print '2' * 50
  
  proc.terminate()  # <-- terminate the process
  
  print '3' * 50

  And the result in CMD is

  D:\wyx\workspace\python\ffrstp>python test1.py
  
  11111111111111111111111111111111111111111111111111
  
  ffmpeg version N-75563-g235381e Copyright (c) 2000-2015 the FFmpeg developers
  
    built with gcc 4.9.3 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
  
  isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
  
  le-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --
  
  enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm --enable-l
  
  ibilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enab
  
  le-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --en
  
  able-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --ena
  
  ble-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc
  
   --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enabl
  
  e-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-lzma --ena
  
  ble-decklink --enable-zlib
  
    libavutil      55.  2.100 / 55.  2.100
  
    libavcodec     57.  3.100 / 57.  3.100
  
    libavformat    57.  2.100 / 57.  2.100
  
    libavdevice    57.  0.100 / 57.  0.100
  
    libavfilter     6.  8.100 /  6.  8.100
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.100 /  2.  0.100
  
    libpostproc    54.  0.100 / 54.  0.100
  
  Input #0, rtsp, from 'rtsp://218.204.223.237:554/live/1/66251FC11353191F/e7ooqwc
  
  fbqjoo80j.sdp':
  
    Metadata:
  
      title           : RTSP Session
  
      comment         : Jabsco Stream(JCO-jy9757acx1eve7nm-a104aea23c1e17bbc776656
  
  f5069bbf7)
  
    Duration: N/A, start: 0.000000, bitrate: N/A
  
      Stream #0:0: Video: mpeg4 (Simple Profile), yuv420p, 352x288 [SAR 1:1 DAR 11
  
  :9], 10k tbr, 90k tbn, 10k tbc
  
  [mp4 @ 00bad520] Codec for stream 0 does not use global headers but container fo
  
  rmat requires global headers
  
  Output #0, mp4, to 'dump.mp4':
  
    Metadata:
  
      title           : RTSP Session
  
      comment         : Jabsco Stream(JCO-jy9757acx1eve7nm-a104aea23c1e17bbc776656
  
  f5069bbf7)
  
      encoder         : Lavf57.2.100
  
      Stream #0:0: Video: mpeg4 ( [0][0][0] / 0x0020), yuv420p, 352x288 [SAR 1:1 D
  
  AR 11:9], q=2-31, 10k tbr, 90k tbn, 90k tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
  Press [q] to stop, [?] for help
  
  [mp4 @ 00bad520] pts has no value
  
  [mp4 @ 00bad520] Non-monotonous DTS in output stream 0:0; previous: 0, current:
  
  0; changing to 1. This may result in incorrect timestamps in the output file.
  
  [mp4 @ 00bad520] Non-monotonous DTS in output stream 0:0; previous: 1, current:
  
  0; changing to 2. This may result in incorrect timestamps in the output file.
  
  frame=   30 fps=0.0 q=-1.0 size=      63kB time=00:00:02.33 bitrate= 220.4kbits/
  
  frame=   36 fps= 31 q=-1.0 size=      68kB time=00:00:02.95 bitrate= 187.9kbits/
  
  frame=   42 fps= 24 q=-1.0 size=      73kB time=00:00:03.52 bitrate= 169.6kbits/
  
  frame=   47 fps= 20 q=-1.0 size=      90kB time=00:00:04.10 bitrate= 178.9kbits/
  
  frame=   53 fps= 19 q=-1.0 size=      95kB time=00:00:04.63 bitrate= 167.2kbits/
  
  22222222222222222222222222222222222222222222222222
  
  33333333333333333333333333333333333333333333333333
  
  
  
  D:\wyx\workspace\python\ffrstp>frame=   58 fps= 17 q=-1.0 size=      99kB time=0
  
  frame=   64 fps= 16 q=-1.0 size=     104kB time=00:00:05.72 bitrate= 149.0kbits/
  
  frame=   70 fps= 15 q=-1.0 size=     122kB time=00:00:06.36 bitrate= 156.7kbits/
  
  frame=   76 fps= 15 q=-1.0 size=     127kB time=00:00:06.92 bitrate= 150.2kbits/
  
  frame=   82 fps= 14 q=-1.0 size=     132kB time=00:00:07.55 bitrate= 143.2kbits/
  
  [rtsp @ 00adb3e0] max delay reached. need to consume packet
  
  [NULL @ 00add8c0] RTP: missed 7 packets
  
  frame=   86 fps= 13 q=-1.0 size=     135kB time=00:00:07.95 bitrate= 139.5kbits/
  
  [rtsp @ 00adb3e0] max delay reached. need to consume packet
  
  [NULL @ 00add8c0] RTP: missed 3 packets

  Maybe ffmpeg can reconnection. Can I stop it like ’Ctrl + C’ ?
  When I press ’Ctrl+C’,the result is

  22222222222222222222222222222222222222222222222222
  
  33333333333333333333333333333333333333333333333333
  
  
  
  D:\wyx\workspace\python\ffrstp>frame=   58 fps= 17 q=-1.0 size=      99kB time=0
  
  frame=   64 fps= 16 q=-1.0 size=     104kB time=00:00:05.72 bitrate= 149.0kbits/
  
  frame=   70 fps= 15 q=-1.0 size=     122kB time=00:00:06.36 bitrate= 156.7kbits/
  
  frame=   76 fps= 15 q=-1.0 size=     127kB time=00:00:06.92 bitrate= 150.2kbits/
  
  frame=   82 fps= 14 q=-1.0 size=     132kB time=00:00:07.55 bitrate= 143.2kbits/
  
  [rtsp @ 00adb3e0] max delay reached. need to consume packet
  
  [NULL @ 00add8c0] RTP: missed 7 packets
  
  frame=   86 fps= 13 q=-1.0 size=     135kB time=00:00:07.95 bitrate= 139.5kbits/
  
  [rtsp @ 00adb3e0] max delay reached. need to consume packet
  
  [NULL @ 00add8c0] RTP: missed 3 packets
  
  [rtsp @ 00adb3e0] max delay reached. need to consume packet
  
  [NULL @ 00add8c0] RTP: missed 1 packets
  
  frame=   89 fps= 13 q=-1.0 size=     138kB time=00:00:08.35 bitrate= 135.3kbits/
  
  [rtsp @ 00adb3e0] max delay reached. need to consume packet
  
  [NULL @ 00add8c0] RTP: missed 1 packets
  
  [rtsp @ 00adb3e0] max delay reached. need to consume packet
  
  [NULL @ 00add8c0] RTP: missed 3 packets
  
  [rtsp @ 00adb3e0] max delay reached. need to consume packet
  
  [NULL @ 00add8c0] RTP: missed 5 packets
  
  [rtsp @ 00adb3e0] max delay reached. need to consume packet
  
  [NULL @ 00add8c0] RTP: missed 3 packets
  
  [rtsp @ 00adb3e0] max delay reached. need to consume packet
  
  [NULL @ 00add8c0] RTP: missed 1 packets
  
  frame=   92 fps= 12 q=-1.0 size=     144kB time=00:00:09.15 bitrate= 128.7kbits/
  
  frame=   93 fps= 11 q=-1.0 size=     145kB time=00:00:09.58 bitrate= 123.8kbits/
  
  [rtsp @ 00adb3e0] max delay reached. need to consume packet
  
  [NULL @ 00add8c0] RTP: missed 1 packets
  
  [rtsp @ 00adb3e0] max delay reached. need to consume packet
  
  [NULL @ 00add8c0] RTP: missed 2 packets
  
  
  
  
  
  D:\wyx\workspace\python\ffrstp>[rtsp @ 00adb3e0] max delay reached. need to cons
  
  ume packet
  
  [NULL @ 00add8c0] RTP: missed 12 packets
  
  frame=   96 fps= 11 q=-1.0 size=     148kB time=00:00:10.43 bitrate= 116.2kbits/
  
  frame=   96 fps=9.2 q=-1.0 Lsize=     151kB time=00:00:10.43 bitrate= 118.3kbits
  
  /s
  
  video:148kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing o
  
  verhead: 1.913398%
  
  Exiting normally, received signal 2.

• Trying to cancel execution and delete file using ffmpeg C API

  6 mars 2020, par Vuwox

  The code below is a class that handle the conversion of multiples images, through add_frame() method, into a GIF with encode(). It also use a filter to generate and apply the palette. The usage is like this :

  Code call example

  std::unique_ptr gif_obj = nullptr;
  
  try
  
  {
  
      gif_obj = std::make_unique({1000,1000}, 12, "C:/out.gif",
  
                "format=pix_fmts=rgb24,split [a][b];[a]palettegen[p];[b][p]paletteuse");
  
  
  
      // Example: a simple vector of images (usually process internally)
  
      for(auto img : image_vector)
  
           gif_obj->add_frame(img);
  
  
  
      // Once all frame were added, encode the final GIF with the filter applied.
  
      gif_obj->encode();
  
  }
  
  catch(const std::exception& e)
  
  {
  
      // An error occured! We must close FFMPEG properly and delete the created file.
  
      gif_obj->cancel();
  
  }

  I have the following issue. If the code for any reason throw an exception, I call ffmpeg->cancel() and it supposes to delete the GIF file on disk. But this is never working, I assume there is a lock on the file or something like that. So here are my question :

  What is the proper way to close/free ffmpeg object in order to remove the file afterward ?

  ---

  Full class code below

  Header

  // C++ Standard includes    
  
  #include <memory>
  
  #include <string>
  
  #include <vector>
  
  
  
  
  
  // 3rd Party incldues
  
  #ifdef __cplusplus
  
  extern "C" {
  
  #include "libavformat/avformat.h"
  
  #include "libavfilter/avfilter.h"
  
  #include "libavutil/opt.h"
  
  #include "libavfilter/buffersrc.h"
  
  #include "libavfilter/buffersink.h"
  
  #include "libswscale/swscale.h"
  
  #include "libavutil/imgutils.h"
  
  }
  
  #endif
  
  
  
  #define FFMPEG_MSG_LEN 2000
  
  
  
  namespace px
  
  {
  
      namespace GIF
  
      {
  
          class FFMPEG
  
          {
  
          public:
  
              FFMPEG(const px::Point2D<int>&amp; dim,
  
                     const int framerate,
  
                     const std::string&amp; filename,
  
                     const std::string&amp; filter_cmd);
  
  
  
              ~FFMPEG();
  
  
  
              void add_frame(pxImage * const img);
  
              void encode();
  
              void cancel();
  
  
  
          private:
  
  
  
              void init_filters();            // Init everything that needed to filter the input frame.
  
              void init_muxer();              // The muxer that creates the output file.
  
              void muxing_one_frame(AVFrame* frame);
  
              void release();
  
  
  
              int _ret = 0;                   // status code from FFMPEG.
  
              char _err_msg[FFMPEG_MSG_LEN];  // Error message buffer.
  
  
  
  
  
              int m_width = 0;                // The width that all futur images must have to be accepted.
  
              int m_height = 0;               // The height that all futur images must have to be accepted.
  
  
  
              int m_framerate = 0;            // GIF Framerate.
  
              std::string m_filename = "";    // The GIF filename (on cache?)
  
              std::string m_filter_desc = ""; // The FFMPEG filter to apply over the frames.
  
  
  
              bool as_frame = false;
  
  
  
              AVFrame* picture_rgb24 = nullptr;           // Temporary frame that will hold the pxImage in an RGB24 format (NOTE: TOP-LEFT origin)
  
  
  
              AVFormatContext* ofmt_ctx = nullptr;        // ouput format context associated to the 
  
              AVCodecContext* o_codec_ctx = nullptr;      // output codec for the GIF
  
  
  
              AVFilterGraph* filter_graph = nullptr;      // filter graph associate with the string we want to execute
  
              AVFilterContext* buffersrc_ctx = nullptr;   // The buffer that will store all the frames in one place for the palette generation.
  
              AVFilterContext* buffersink_ctx = nullptr;  // The buffer that will store the result afterward (once the palette are used).
  
  
  
              int64_t m_pts_increment = 0;
  
          };
  
      };
  
  };
  
  </int></vector></string></memory>

  ctor

  px::GIF::FFMPEG::FFMPEG(const px::Point2D<int>&amp; dim,
  
                          const int framerate,
  
                          const std::string&amp; filename,
  
                          const std::string&amp; filter_cmd) :
  
      m_width(dim.x()),
  
      m_height(dim.y()),
  
      m_framerate(framerate),
  
      m_filename(filename),
  
      m_filter_desc(filter_cmd)
  
  {
  
  #if !_DEBUG
  
      av_log_set_level(AV_LOG_QUIET); // Set the FFMPEG log to quiet to avoid too much logs.
  
  #endif
  
  
  
      // Allocate the temporary buffer that hold the ffmpeg image (pxImage to AVFrame conversion).
  
      picture_rgb24 = av_frame_alloc();
  
      picture_rgb24->pts = 0;
  
      picture_rgb24->data[0] = NULL;
  
      picture_rgb24->linesize[0] = -1;
  
      picture_rgb24->format = AV_PIX_FMT_RGB24;
  
      picture_rgb24->height = m_height;
  
      picture_rgb24->width = m_width; 
  
  
  
      if ((_ret = av_image_alloc(picture_rgb24->data, picture_rgb24->linesize, m_width, m_height, (AVPixelFormat)picture_rgb24->format, 24)) &lt; 0)
  
          throw px::GIF::Error("Failed to allocate the AVFrame for pxImage conversion with error: " +
  
                               std::string(av_make_error_string(_err_msg, FFMPEG_MSG_LEN, _ret)),
  
                               "GIF::FFMPEG CTOR");   
  
  
  
      //printf("allocated picture of size %d, linesize %d %d %d %d\n", _ret, picture_rgb24->linesize[0], picture_rgb24->linesize[1], picture_rgb24->linesize[2], picture_rgb24->linesize[3]);
  
  
  
      init_muxer();   // Prepare the GIF encoder (open it on disk).
  
      init_filters(); // Prepare the filter that will be applied over the frame.
  
  
  
      // Instead of hardcoder {1,100} which is the GIF tbn, we collect it from its stream.
  
      // This will avoid future problem if the codec change in ffmpeg.
  
      if (ofmt_ctx &amp;&amp; ofmt_ctx->nb_streams > 0)
  
          m_pts_increment = av_rescale_q(1, { 1, m_framerate }, ofmt_ctx->streams[0]->time_base);
  
      else
  
          m_pts_increment = av_rescale_q(1, { 1, m_framerate }, { 1, 100 });
  
  }
  
  </int>

  FFMPEG Initialization (Filter and muxer)

  void px::GIF::FFMPEG::init_filters()
  
  {
  
      const AVFilter* buffersrc = avfilter_get_by_name("buffer");
  
      const AVFilter* buffersink = avfilter_get_by_name("buffersink");
  
  
  
      AVRational time_base = { 1, m_framerate };
  
      AVRational aspect_pixel = { 1, 1 };
  
  
  
      AVFilterInOut* inputs = avfilter_inout_alloc();
  
      AVFilterInOut* outputs = avfilter_inout_alloc();
  
  
  
      filter_graph = avfilter_graph_alloc();
  
  
  
      try
  
      {
  
          if (!outputs || !inputs || !filter_graph)
  
              throw px::GIF::Error("Failed to 'init_filters' could not allocated the graph/filters.", "GIF::FFMPEG init_filters");
  
  
  
          char args[512];
  
          snprintf(args, sizeof(args),
  
                   "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
  
                   m_width, m_height,
  
                   picture_rgb24->format,
  
                   time_base.num, time_base.den,
  
                   aspect_pixel.num, aspect_pixel.den);
  
  
  
          if (avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in", args, nullptr, filter_graph) < 0)
  
              throw px::GIF::Error("Failed to create the 'source buffer' in init_filer method.", "GIF::FFMPEG init_filters");
  
  
  
  
  
          if (avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out", nullptr, nullptr, filter_graph) < 0)
  
              throw px::GIF::Error("Failed to create the 'sink buffer' in init_filer method.", "GIF::FFMPEG init_filters");
  
  
  
          // GIF has possible output of PAL8.
  
          enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_PAL8, AV_PIX_FMT_NONE };
  
  
  
          if (av_opt_set_int_list(buffersink_ctx, "pix_fmts", pix_fmts, AV_PIX_FMT_NONE, AV_OPT_SEARCH_CHILDREN) < 0)
  
              throw px::GIF::Error("Failed to set the output pixel format.", "GIF::FFMPEG init_filters");
  
  
  
          outputs->name = av_strdup("in");
  
          outputs->filter_ctx = buffersrc_ctx;
  
          outputs->pad_idx = 0;
  
          outputs->next = nullptr;
  
  
  
          inputs->name = av_strdup("out");
  
          inputs->filter_ctx = buffersink_ctx;
  
          inputs->pad_idx = 0;
  
          inputs->next = nullptr;
  
  
  
          // GIF has possible output of PAL8. 
  
          if (avfilter_graph_parse_ptr(filter_graph, m_filter_desc.c_str(), &inputs, &outputs, nullptr) < 0)
  
              throw px::GIF::Error("Failed to parse the filter graph (bad string!).", "GIF::FFMPEG init_filters");
  
  
  
          if (avfilter_graph_config(filter_graph, nullptr) < 0)
  
              throw px::GIF::Error("Failed to configure the filter graph (bad string!).", "GIF::FFMPEG init_filters");
  
  
  
          avfilter_inout_free(&inputs);
  
          avfilter_inout_free(&outputs);
  
      }
  
      catch (const std::exception& e)
  
      {
  
          // Catch exception to delete element.
  
          avfilter_inout_free(&inputs);
  
          avfilter_inout_free(&outputs);
  
          throw e; // re-throuw
  
      }
  
  }
  
  
  
  
  
  void px::GIF::FFMPEG::init_muxer()
  
  {
  
      AVOutputFormat* o_fmt = av_guess_format("gif", m_filename.c_str(), "video/gif");
  
  
  
      if ((_ret = avformat_alloc_output_context2(&ofmt_ctx, o_fmt, "gif", m_filename.c_str())) < 0)
  
          throw px::GIF::Error(std::string(av_make_error_string(_err_msg, FFMPEG_MSG_LEN, _ret)) + " allocate output format.", "GIF::FFMPEG init_muxer");
  
  
  
      AVCodec* codec = avcodec_find_encoder(AV_CODEC_ID_GIF);
  
      if (!codec) throw px::GIF::Error("Could to find the 'GIF' codec.", "GIF::FFMPEG init_muxer");
  
  
  
  #if 0
  
      const AVPixelFormat* p = codec->pix_fmts;
  
      while (p != NULL && *p != AV_PIX_FMT_NONE) {
  
          printf("supported pix fmt: %s\n", av_get_pix_fmt_name(*p));
  
          ++p;
  
      }
  
  #endif
  
  
  
      AVStream* stream = avformat_new_stream(ofmt_ctx, codec);
  
  
  
      AVCodecParameters* codec_paramters = stream->codecpar;
  
      codec_paramters->codec_tag = 0;
  
      codec_paramters->codec_id = codec->id;
  
      codec_paramters->codec_type = AVMEDIA_TYPE_VIDEO;
  
      codec_paramters->width = m_width;
  
      codec_paramters->height = m_height;
  
      codec_paramters->format = AV_PIX_FMT_PAL8;
  
  
  
      o_codec_ctx = avcodec_alloc_context3(codec);
  
      avcodec_parameters_to_context(o_codec_ctx, codec_paramters);
  
  
  
      o_codec_ctx->time_base = { 1, m_framerate };
  
  
  
      if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
  
          o_codec_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
  
  
  
      if ((_ret = avcodec_open2(o_codec_ctx, codec, NULL)) < 0)
  
          throw px::GIF::Error(std::string(av_make_error_string(_err_msg, FFMPEG_MSG_LEN, _ret)) + " open output codec.", "GIF::FFMPEG init_muxer");
  
  
  
      if ((_ret = avio_open(&ofmt_ctx->pb, m_filename.c_str(), AVIO_FLAG_WRITE)) < 0)
  
          throw px::GIF::Error(std::string(av_make_error_string(_err_msg, FFMPEG_MSG_LEN, _ret)) + " avio open error.", "GIF::FFMPEG init_muxer");
  
  
  
      if ((_ret = avformat_write_header(ofmt_ctx, NULL)) < 0)
  
          throw px::GIF::Error(std::string(av_make_error_string(_err_msg, FFMPEG_MSG_LEN, _ret)) + " write GIF header", "GIF::FFMPEG init_muxer");
  
  
  
  #if _DEBUG
  
      // This print the stream/output format.
  
      av_dump_format(ofmt_ctx, -1, m_filename.c_str(), 1);
  
  #endif
  
  }

  Add frame (usually in a loop)

  void px::GIF::FFMPEG::add_frame(pxImage * const img)
  
  {
  
      if (img->getImageType() != PXT_BYTE || img->getNChannels() != 4)
  
          throw px::GIF::Error("Failed to 'add_frame' since image is not PXT_BYTE and 4-channels.", "GIF::FFMPEG add_frame");
  
  
  
      if (img->getWidth() != m_width || img->getHeight() != m_height)
  
          throw px::GIF::Error("Failed to 'add_frame' since the size is not same to other inputs.", "GIF::FFMPEG add_frame");
  
  
  
      const int pitch = picture_rgb24->linesize[0];
  
      auto px_ptr = getImageAccessor(img);
  
  
  
      for (int y = 0; y < m_height; y++)
  
      {
  
          const int px_row = img->getOrigin() == ORIGIN_BOT_LEFT ? m_height - y - 1 : y;
  
          for (int x = 0; x < m_width; x++)
  
          {
  
              const int idx = y * pitch + 3 * x;
  
              picture_rgb24->data[0][idx] = px_ptr[px_row][x].ch[PX_RE];
  
              picture_rgb24->data[0][idx + 1] = px_ptr[px_row][x].ch[PX_GR];
  
              picture_rgb24->data[0][idx + 2] = px_ptr[px_row][x].ch[PX_BL];
  
          }
  
      }
  
  
  
      // palettegen need a whole stream, just add frame to buffer.
  
      if ((_ret = av_buffersrc_add_frame_flags(buffersrc_ctx, picture_rgb24, AV_BUFFERSRC_FLAG_KEEP_REF)) < 0)
  
          throw px::GIF::Error("Failed to 'add_frame' to global buffer with error: " +
  
                               std::string(av_make_error_string(_err_msg, FFMPEG_MSG_LEN, _ret)),
  
                               "GIF::FFMPEG add_frame");
  
  
  
      // Increment the FPS of the picture for the next add-up to the buffer.      
  
      picture_rgb24->pts += m_pts_increment;
  
  
  
      as_frame = true;
  
  }    

  Encoder (final step)

  void px::GIF::FFMPEG::encode()
  
  {
  
      if (!as_frame)
  
          throw px::GIF::Error("Please 'add_frame' before running the Encoding().", "GIF::FFMPEG encode");
  
  
  
      // end of buffer
  
      if ((_ret = av_buffersrc_add_frame_flags(buffersrc_ctx, nullptr, AV_BUFFERSRC_FLAG_KEEP_REF)) < 0)
  
          throw px::GIF::Error("error add frame to buffer source: " + std::string(av_make_error_string(_err_msg, FFMPEG_MSG_LEN, _ret)), "GIF::FFMPEG encode");
  
  
  
      do {
  
          AVFrame* filter_frame = av_frame_alloc();
  
          _ret = av_buffersink_get_frame(buffersink_ctx, filter_frame);
  
          if (_ret == AVERROR(EAGAIN) || _ret == AVERROR_EOF) {
  
              av_frame_unref(filter_frame);
  
              break;
  
          }
  
  
  
          // write the filter frame to output file
  
          muxing_one_frame(filter_frame);
  
  
  
          av_frame_unref(filter_frame);
  
      } while (_ret >= 0);
  
  
  
      av_write_trailer(ofmt_ctx);
  
  }
  
  
  
  void px::GIF::FFMPEG::muxing_one_frame(AVFrame* frame)
  
  {
  
      int ret = avcodec_send_frame(o_codec_ctx, frame);
  
      AVPacket *pkt = av_packet_alloc();
  
      av_init_packet(pkt);
  
  
  
      while (ret >= 0) {
  
          ret = avcodec_receive_packet(o_codec_ctx, pkt);
  
          if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
  
              break;
  
          }
  
  
  
          av_write_frame(ofmt_ctx, pkt);
  
      }
  
      av_packet_unref(pkt);
  
  }

  DTOR, Release and Cancel

  px::GIF::FFMPEG::~FFMPEG()
  
  {
  
      release();
  
  }
  
  
  
  
  
  void px::GIF::FFMPEG::release()
  
  {
  
      // Muxer stuffs
  
      if (ofmt_ctx != nullptr) avformat_free_context(ofmt_ctx);
  
      if (o_codec_ctx != nullptr) avcodec_close(o_codec_ctx);
  
      if (o_codec_ctx != nullptr) avcodec_free_context(&o_codec_ctx);
  
  
  
      ofmt_ctx = nullptr;
  
      o_codec_ctx = nullptr;
  
  
  
      // Filter stuffs
  
      if (buffersrc_ctx != nullptr) avfilter_free(buffersrc_ctx);
  
      if (buffersink_ctx != nullptr) avfilter_free(buffersink_ctx);
  
      if (filter_graph != nullptr) avfilter_graph_free(&filter_graph);
  
  
  
      buffersrc_ctx = nullptr;
  
      buffersink_ctx = nullptr;
  
      filter_graph = nullptr;
  
  
  
      // Conversion image.
  
      if (picture_rgb24 != nullptr) av_frame_free(&picture_rgb24);
  
      picture_rgb24 = nullptr;
  
  }
  
  
  
  void px::GIF::FFMPEG::cancel()
  
  {
  
      // In-case of failure we must close ffmpeg and exit.
  
      av_write_trailer(ofmt_ctx);
  
  
  
      // Release and close all elements.
  
      release();
  
  
  
      // Delete the file on disk.
  
      if (remove(m_filename.c_str()) != 0)
  
          PX_LOG0(PX_LOGLEVEL_ERROR, "GIF::FFMPEG - On 'cancel' failed to remove the file.");
  
  }