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• Video too fast FFmpeg

  22 novembre 2012, par Spamdark

  I am having an issue again with ffmpeg, I'm a newbie with ffmpeg, and I can't find a good tutorial up to date...

  This time, when I play a video with ffmpeg, it plays too fast, ffmpeg is ignoring the FPS, I don't want to handle that with a thread sleep, because the videos have differents FPS's.

  I created a thread, there you can find the loop :

  AVPacket framepacket;
  
  
  
  while(av_read_frame(formatContext,&framepacket)>= 0){
  
      pausecontrol.lock();
  
  
  
      // Is it a video or audio frame¿?
  
      if(framepacket.stream_index==gotVideoCodec){
  
          int framereaded;
  
          // Video? Ok
  
          avcodec_decode_video2(videoCodecContext,videoFrame,&framereaded,&framepacket);
  
          // Yeah, did we get it?
  
          if(framereaded && doit){
  
              AVRational millisecondbase = {1,1000};
  
              int f_number = framepacket.dts;
  
              int f_time = av_rescale_q(framepacket.dts,formatContext->streams[gotVideoCodec]->time_base,millisecondbase);
  
              currentTime=f_time;
  
              currentFrameNumber=f_number;
  
  
  
              int stWidth = videoCodecContext->width;
  
              int stHeight = videoCodecContext->height;
  
              SwsContext *ctx = sws_getContext(stWidth, stHeight, videoCodecContext->pix_fmt, stWidth,
  
              stHeight, PIX_FMT_RGB24, SWS_BICUBIC, NULL, NULL, NULL);
  
              if(ctx!=0){
  
              sws_scale(ctx,videoFrame->data,videoFrame->linesize,0,videoCodecContext->height,videoFrameRGB->data,videoFrameRGB->linesize);
  
              QImage framecapsule=QImage(stWidth,stHeight,QImage::Format_RGB888);
  
  
  
              for(int y=0;ydata[0]+y*videoFrameRGB->linesize[0],stWidth*3);
  
              }
  
              emit newFrameReady(framecapsule);
  
              sws_freeContext(ctx);
  
              }
  
  
  
          }
  
      }
  
      if(framepacket.stream_index==gotAudioCodec){
  
          // Audio? Ok
  
      }
  
      pausecontrol.unlock();
  
      av_free_packet(&framepacket);
  
  }

  Any Idea ?

• Cannot save animation in matplotlib : Windows permission denied

  13 mai 2015, par Vladimir

  I’ve been trying for a day long to sort this out, checking similar threads but with no success.
  Stretch’s Cannot save matplotlib animation with ffmpeg helped with previous errors (I had ffmpeg path wrong), but I kept getting Access denied after fixing it.

  My ffmpeg binary is on C:\ffmpeg\bin

  A nice alternative would be to able to export gif files, but I keep getting an ascii error with imagemagick. I think both problems are related, so I wanted to sort out the ffmpeg first.

  I think the problem might have to do with the fact I’m working with Canopy (in Windows 8 64bit), which pretty much hegemonized my path variable and broke some things along the way (e.g. I can’t open IDLE since I installed Canopy, didn’t tried to fix that yet). As I fixed things along the way I found at least 3 distinct path variables, all of which I updated : windows advanced settings path (set manually), windows console path (set via console with setx), and sys.path (set or checked at runtime), adding ";C:\ffmpeg\bin", where ffmpeg effectively is. Regardless I sort out the problem or not, I would like to learn which of these environment variables are relevant for what, I find it very confusing.

  The code is the following :

  # -*- coding: utf-8 -*-
  
  import sys
  
  import numpy as np
  
  from matplotlib import pyplot as plt
  
  from matplotlib import animation
  
  plt.rcParams['animation.ffmpeg_path'] = r'C:\ffmpeg\bin'
  
  if r'C:\ffmpeg\bin' not in sys.path: sys.path.append(r'C:\ffmpeg\bin')
  
  
  
  fig = plt.figure()
  
  ax = plt.axes(xlim=(0, 2), ylim=(-2, 2))
  
  line, = ax.plot([], [], lw=2)
  
  
  
  def init():
  
      line.set_data([], [])
  
      return line,
  
  
  
  def animate(i):
  
      x = np.linspace(0, 2, 1000)
  
      y = np.sin(2 * np.pi * (x - 0.01 * i))
  
      line.set_data(x, y)
  
      return line,
  
  
  
  anim = animation.FuncAnimation(fig, animate, init_func=init, frames=200, interval=20, blit=True)
  
  plt.show()
  
  
  
  # This case generates Windows err: Access Denied
  
  FFwriter = animation.FFMpegWriter()
  
  # anim.save(r'C:\basic_animation.mp4', writer = FFwriter, fps=30)
  
  
  
  # This case generates UnicodeDecodeError:'ascii' codec can't decode byte 0xa0 in position 3
  
  # anim.save(r'C:\animation.gif', writer='imagemagick', fps=30)

  The traceback for anim.save(r'C:\basic_animation.mp4', writer = FFwriter, fps=30) :

  %run "C:\Users\Yahveh\Documents\Vlad\Investigacion\animation saving.py"
  
  ---------------------------------------------------------------------------
  
  WindowsError                              Traceback (most recent call last)
  
  C:\Users\Yahveh\Documents\Vlad\Investigacion\animation saving.py in <module>()
  
       27 # This case generates Windows err: Access Denied
  
       28 FFwriter = animation.FFMpegWriter()
  
  ---> 29 anim.save(r'C:\basic_animation.mp4', writer = FFwriter, fps=30)
  
       30 
  
       31 # This case generates UnicodeDecodeError:'ascii' codec can't decode byte 0xa0 in position 3
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\User\lib\site-packages\matplotlib\animation.pyc in save(self, filename, writer, fps, dpi, codec, bitrate, extra_args, metadata, extra_anim, savefig_kwargs)
  
      759         # since GUI widgets are gone. Either need to remove extra code to
  
      760         # allow for this non-existant use case or find a way to make it work.
  
  --> 761         with writer.saving(self._fig, filename, dpi):
  
      762             for data in zip(*[a.new_saved_frame_seq()
  
      763                               for a in all_anim]):
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\App\appdata\canopy-1.5.2.2785.win-x86_64\lib\contextlib.pyc in __enter__(self)
  
       15     def __enter__(self):
  
       16         try:
  
  ---> 17             return self.gen.next()
  
       18         except StopIteration:
  
       19             raise RuntimeError("generator didn't yield")
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\User\lib\site-packages\matplotlib\animation.pyc in saving(self, *args)
  
      184         '''
  
      185         # This particular sequence is what contextlib.contextmanager wants
  
  --> 186         self.setup(*args)
  
      187         yield
  
      188         self.finish()
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\User\lib\site-packages\matplotlib\animation.pyc in setup(self, fig, outfile, dpi, *args)
  
      174         # Run here so that grab_frame() can write the data to a pipe. This
  
      175         # eliminates the need for temp files.
  
  --> 176         self._run()
  
      177 
  
      178     @contextlib.contextmanager
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\User\lib\site-packages\matplotlib\animation.pyc in _run(self)
  
      202                                       stdout=output, stderr=output,
  
      203                                       stdin=subprocess.PIPE,
  
  --> 204                                       creationflags=subprocess_creation_flags)
  
      205 
  
      206     def finish(self):
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\App\appdata\canopy-1.5.2.2785.win-x86_64\lib\subprocess.pyc in __init__(self, args, bufsize, executable, stdin, stdout, stderr, preexec_fn, close_fds, shell, cwd, env, universal_newlines, startupinfo, creationflags)
  
      707                                 p2cread, p2cwrite,
  
      708                                 c2pread, c2pwrite,
  
  --> 709                                 errread, errwrite)
  
      710         except Exception:
  
      711             # Preserve original exception in case os.close raises.
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\App\appdata\canopy-1.5.2.2785.win-x86_64\lib\subprocess.pyc in _execute_child(self, args, executable, preexec_fn, close_fds, cwd, env, universal_newlines, startupinfo, creationflags, shell, to_close, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite)
  
      955                                          env,
  
      956                                          cwd,
  
  --> 957                                          startupinfo)
  
      958             except pywintypes.error, e:
  
      959                 # Translate pywintypes.error to WindowsError, which is
  
  
  
  WindowsError: [Error 5] Acceso denegado 
  
  </module>

  The traceback for anim.save(r'C:\animation.gif', writer='imagemagick', fps=30) :

  In [8]: %run "C:\Users\Yahveh\Documents\Vlad\Investigacion\animation saving.py"
  
  ---------------------------------------------------------------------------
  
  UnicodeDecodeError                        Traceback (most recent call last)
  
  C:\Users\Yahveh\Documents\Vlad\Investigacion\animation saving.py in <module>()
  
       30 
  
       31 # This case generates UnicodeDecodeError:'ascii' codec can't decode byte 0xa0 in position 3
  
  ---> 32 anim.save(r'C:\animation.gif', writer='imagemagick', fps=30)
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\User\lib\site-packages\matplotlib\animation.pyc in save(self, filename, writer, fps, dpi, codec, bitrate, extra_args, metadata, extra_anim, savefig_kwargs)
  
      765                     # TODO: Need to see if turning off blit is really necessary
  
      766                     anim._draw_next_frame(d, blit=False)
  
  --> 767                 writer.grab_frame(**savefig_kwargs)
  
      768 
  
      769         # Reconnect signal for first draw if necessary
  
  
  
  C:\Users\Yahveh\AppData\Local\Enthought\Canopy\User\lib\site-packages\matplotlib\animation.pyc in grab_frame(self, **savefig_kwargs)
  
      225             verbose.report('MovieWriter -- Error '
  
      226                            'running proc:\n%s\n%s' % (out,
  
  --> 227                                                       err), level='helpful')
  
      228             raise
  
      229 
  
  
  
  UnicodeDecodeError: 'ascii' codec can't decode byte 0xa0 in position 3: ordinal not in range(128) 
  
  </module>

  Stared at them for a while.

  Thanks for your time !

  UPDATE : I followed the steps in this post for granting access to both C :\ffmpeg and destination folder, but no luck :(

• FFmpeg H264 parsing

  20 mai 2015, par Yoohoo

  I am using FFmpeg to decoding H.264 video, for the following program :

      #include 
  
      #include 
  
      #include 
  
      #include 
  
  
  
      #include <sys></sys>time.h>
  
      #include 
  
  
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavutil></libavutil>mathematics.h>
  
  
  
  #include <sdl></sdl>SDL.h>
  
  
  
  void sigint_handler(int signal) {
  
      printf("\n");
  
      exit(0);
  
  }
  
  
  
  const char *window_title;
  
  SDL_Surface *screen;
  
  SDL_Overlay *yuv_overlay;
  
  
  
  #define INBUF_SIZE 80000
  
  
  
  /*
  
   * Video decoding example
  
   */
  
  
  
  static long get_time_diff(struct timeval time_now) {
  
     struct timeval time_now2;
  
     gettimeofday(&amp;time_now2,0);
  
     return time_now2.tv_sec*1.e6 - time_now.tv_sec*1.e6 + time_now2.tv_usec - time_now.tv_usec;
  
  }
  
  
  
  int video_open(AVCodecContext *avctx, const char *filename){
  
      int flags = SDL_HWSURFACE|SDL_ASYNCBLIT|SDL_HWACCEL;
  
      int w,h;
  
  
  
      flags |= SDL_RESIZABLE;
  
  
  
      if (avctx->width){
  
          w = avctx->width;
  
          h = avctx->height;
  
      } else {
  
          w = 640;
  
          h = 480;
  
      }
  
  
  
      if(SDL_Init(SDL_INIT_VIDEO) &lt; 0) {
  
      fprintf(stderr, "SDL_INIT_VIDEO failed!\n");
  
      exit(1);
  
      }
  
  
  
      screen = SDL_SetVideoMode(w, h, 0, flags);
  
  
  
      if (!screen) {
  
          fprintf(stderr, "SDL: could not set video mode - exiting\n");
  
          return -1;
  
      }
  
      if (!window_title)
  
          window_title = filename;
  
      SDL_WM_SetCaption(window_title, window_title);
  
  
  
      yuv_overlay = SDL_CreateYUVOverlay(w, h, SDL_YV12_OVERLAY, screen);
  
  
  
      if (yuv_overlay->hw_overlay) {
  
      fprintf(stderr, "Using hardware overlay!\n");
  
      }
  
  
  
      return 0;
  
  }
  
  
  
  int main(int argc, char **argv) {
  
      AVCodec *codec;
  
      AVCodecContext *c= NULL;
  
      AVCodecParserContext *parser = NULL;
  
      int frame, got_picture, len2, len;
  
      const char *filename;
  
      FILE *f;
  
      AVFrame *picture;
  
      char *arghwtf = malloc(INBUF_SIZE);
  
      char *luma = NULL;
  
      char *chroma = NULL;
  
      int i=0;
  
      uint64_t in_len;
  
      int pts, dts;
  
      struct timeval t;
  
      float inv_fps = 1e6/23.98;
  
      AVPacket avpkt;
  
      SDL_Rect rect;
  
  
  
  
  
      /* register all the codecs */
  
      avcodec_register_all();
  
  
  
      filename = argv[1];
  
  
  
      av_init_packet(&amp;avpkt);
  
  
  
      printf("Decoding file %s...\n", filename);
  
  
  
      /* find the H.264 video decoder */
  
      codec = avcodec_find_decoder(CODEC_ID_H264);
  
      if (!codec) {
  
          fprintf(stderr, "codec not found\n");
  
          exit(1);
  
      }
  
  
  
      c = avcodec_alloc_context3(codec);
  
      picture = avcodec_alloc_frame();
  
  
  
      c->skip_loop_filter = 48; // skiploopfilter=all
  
  
  
      if (avcodec_open(c, codec) &lt; 0) {
  
          fprintf(stderr, "could not open codec\n");
  
          exit(1);
  
      }
  
  
  
      /* the codec gives us the frame size, in samples */
  
      parser = av_parser_init(c->codec_id);
  
      parser->flags |= PARSER_FLAG_ONCE;
  
  
  
      f = fopen(filename, "rb");
  
      if (!f) {
  
          fprintf(stderr, "could not open %s\n", filename);
  
          exit(1);
  
      }
  
  
  
      frame = 0;
  
      gettimeofday(&amp;t, 0);
  
      if(fread(arghwtf, 1, INBUF_SIZE, f) == 0) {
  
      exit(1);
  
      }
  
      in_len = 80000;
  
          while (in_len > 0 &amp;&amp; !feof(f)) {
  
          len = av_parser_parse2(parser, c, &amp;avpkt.data, &amp;avpkt.size, arghwtf, in_len,
  
                                     pts, dts, AV_NOPTS_VALUE);
  
  
  
              len2 = avcodec_decode_video2(c, picture, &amp;got_picture, &amp;avpkt);
  
              if (len2 &lt; 0) {
  
                  fprintf(stderr, "Error while decoding frame %d\n", frame);
  
                  exit(1);
  
              }
  
              if (got_picture) {
  
          if(!screen) {
  
              video_open(c, filename);
  
  
  
              rect.x = 0;
  
              rect.y = 0;
  
              rect.w = c->width;
  
              rect.h = c->height;
  
              inv_fps = av_q2d(c->time_base);
  
              fprintf(stderr, "w:%i h:%i\n", rect.w, rect.h);
  
  
  
              luma = malloc(c->width*c->height);
  
              chroma = malloc(c->width*c->height/4);
  
  
  
              SDL_DisplayYUVOverlay(yuv_overlay, &amp;rect);
  
  
  
              signal(SIGINT, sigint_handler);
  
          }
  
                  fprintf(stderr, "\rDisplaying %c:frame %3d (%02d:%02d)...", av_get_pict_type_char(picture->pict_type), frame, frame/1440, (frame/24)%60);
  
                  fflush(stderr);
  
  
  
          SDL_LockYUVOverlay(yuv_overlay);
  
  
  
                  for(i=0;iheight;i++) {
  
                    memcpy(luma + i * c->width, picture->data[0] + i * picture->linesize[0], c->width);
  
                  }
  
          memcpy(yuv_overlay->pixels[0], luma, c->width * c->height);
  
                  for(i=0;iheight/2;i++) {
  
                    memcpy(chroma + i * c->width/2, picture->data[2] + i * picture->linesize[2], c->width/2);
  
                  }
  
          memcpy(yuv_overlay->pixels[1], chroma, c->width * c->height / 4);
  
                  for(i=0;iheight/2;i++) {
  
                    memcpy(chroma + i * c->width/2, picture->data[1] + i * picture->linesize[1], c->width/2);
  
                  }
  
          memcpy(yuv_overlay->pixels[2], chroma, c->width * c->height / 4);
  
  
  
          SDL_UnlockYUVOverlay(yuv_overlay);
  
          SDL_DisplayYUVOverlay(yuv_overlay, &amp;rect);
  
  
  
          while(get_time_diff(t) &lt; inv_fps) {
  
              sleep(1000);
  
          }
  
                  frame++;
  
          gettimeofday(&amp;t, 0);
  
              }
  
          memcpy(arghwtf, arghwtf + len, 80000-len);
  
          fread(arghwtf + 80000 - len, 1, len, f);
  
          }
  
  
  
      /* some codecs, such as MPEG, transmit the I and P frame with a
  
         latency of one frame. You must do the following to have a
  
         chance to get the last frame of the video */
  
      avpkt.data = NULL;
  
      avpkt.size = 0;
  
      len = avcodec_decode_video2(c, picture, &amp;got_picture, &amp;avpkt);
  
      if (got_picture) {
  
          printf("saving last frame %3d\n", frame);
  
          fflush(stdout);
  
  
  
      /* Display last frame here, same code as in the decoding loop above. */
  
  
  
          frame++;
  
      }
  
  
  
      fclose(f);
  
  
  
      avcodec_close(c);
  
      av_free(c);
  
      av_free(picture);
  
      printf("\n");
  
  }

  It gives error :

  ||=== H264_decoding, Debug ===|
  
  /home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp||In function ‘int main(int, char**)’:|
  
  /home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|107|error: invalid conversion from ‘void*’ to ‘char*’ [-fpermissive]|
  
  /home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|136|warning: ‘AVFrame* avcodec_alloc_frame()’ is deprecated (declared at /home/yoohoo/ffmpeg_build/include/libavcodec/avcodec.h:3629) [-Wdeprecated-declarations]|
  
  /home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|136|warning: ‘AVFrame* avcodec_alloc_frame()’ is deprecated (declared at /home/yoohoo/ffmpeg_build/include/libavcodec/avcodec.h:3629) [-Wdeprecated-declarations]|
  
  /home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|138|error: invalid conversion from ‘int’ to ‘AVDiscard’ [-fpermissive]|
  
  /home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|140|error: ‘avcodec_open’ was not declared in this scope|
  
  /home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|163|error: invalid conversion from ‘char*’ to ‘const uint8_t* {aka const unsigned char*}’ [-fpermissive]|
  
  /home/yoohoo/ffmpeg_build/include/libavcodec/avcodec.h|4465|error:   initializing argument 5 of ‘int av_parser_parse2(AVCodecParserContext*, AVCodecContext*, uint8_t**, int*, const uint8_t*, int, int64_t, int64_t, int64_t)’ [-fpermissive]|
  
  /home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|181|error: invalid conversion from ‘void*’ to ‘char*’ [-fpermissive]|
  
  /home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|182|error: invalid conversion from ‘void*’ to ‘char*’ [-fpermissive]|
  
  /home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|188|error: ‘av_get_pict_type_char’ was not declared in this scope|
  
  /home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|210|error: ‘sleep’ was not declared in this scope|
  
  ||=== Build finished: 9 errors, 2 warnings ===|

  I am wondering it is an incompatible problem due to I move this C program to C++, but I finally need to use it in C++. How to solve these invalid conversion problem ? Thanks in advance !