Recherche avancée

Sur d’autres sites (10982)

• Adobe Air , NativeProcess and ffmpeg

  18 août 2013, par Tom Lecoz

  First of all, please excuse me if my english is not perfect, I hope you could understand me...

  I discover yesterday this video tutorial about Air Native Process and FFMPEG, it shows how to create an Air app that can read every video format (avi, mkv, ...).

  http://www.youtube.com/watch?v=6N7eN9wvAGQ

  I tryed to reproduce it but obviously it didn't work...

  Then I looked for an example of it, with working source code, on the internet. I found this

  http://suzhiyam.wordpress.com/2011/05/05/as3ffmpeg-play-multi-video-formats-in-air/

  The author said it's a document class for a Flash project, it just need a button component, a text area and a video Object.

  I tryed it inside a Flash project, it didn't work...
  So, I made some adjusment to run it outside Flash (I just replaced the DisplayObject on the stage by ActionScript code), just because it easier if you want to test it.

  When I say "it didn't work", I mean my video is not read at all. The nativeProcess is working, my executable is recognize but I always get some ProgressEvent.STANDARD_ERROR_DATA and then the process stop...

  I'm working on Windows 7 64 bit.
  I tryed with FFMPEG 32 & 64 bit and get the exact same (no) result.

  You can find my code here
  pastebin.com/U3xRUKWe

  Can someone help me ?

  Please ! :)

  Thanks by advance !

  Tom

• ffmpeg video keep ref frame of source

  9 avril 2021, par user3449922

  I like to keep the some ref frame of source (in this case ref =1) :

  


  Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L3
Format settings                          : CABAC / 1 Ref Frames
Format settings, CABAC                   : Yes
Format settings, Reference frames        : 1 frame
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 6 min 19 s
Bit rate                                 : 388 kb/s
Width                                    : 640 pixels
Height                                   : 480 pixels
Display aspect ratio                     : 4:3
Frame rate mode                          : Variable
Frame rate                               : 9.479 FPS
Minimum frame rate                       : 3.750 FPS
Maximum frame rate                       : 30.030 FPS
Original frame rate                      : 30.000 FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.133
Stream size                              : 17.5 MiB (74%)
Language                                 : English
Codec configuration box                  : avcC


  


  here the output

  


     ID                                       : 1
    Format                                   : AVC
    Format/Info                              : Advanced Video Codec
    Format profile                           : High@L3
    Format settings                          : CABAC  2 Ref Frames
    Format settings, CABAC                   : Yes
    Format settings, Reference frames        : 2 frames
    Codec ID                                 : avc1
    Codec ID/Info                            : Advanced Video Coding
   


  


  the output Ref Frames are 2 , but I like to keep to 1 or directly force to 1.

  


  There is a way to do it ?

  


  Thanks !

  


• FFmpeg - MJPEG decoding - getting different values

  27 décembre 2016, par ahmadh

  I have a set of JPEG frames which I am muxing into an avi, which gives me a mjpeg video. This is the command I run on the console :

  ffmpeg -y -start_number 0 -i %06d.JPEG -codec copy vid.avi

  When I try to demux the video using ffmpeg C api, I get frames which are slightly different in values. Demuxing code looks something like this :

  AVFormatContext* fmt_ctx = NULL;
  
  AVCodecContext* cdc_ctx = NULL;
  
  AVCodec* vid_cdc = NULL;
  
  int ret;
  
  unsigned int height, width;
  
  
  
  ....
  
  // read_nframes is the number of frames to read
  
  output_arr = new unsigned char [height * width * 3 * 
  
                                  sizeof(unsigned char) * read_nframes];
  
  
  
  avcodec_open2(cdc_ctx, vid_cdc, NULL);
  
  
  
  int num_bytes;
  
  uint8_t* buffer = NULL;
  
  const AVPixelFormat out_format = AV_PIX_FMT_RGB24;
  
  
  
  num_bytes = av_image_get_buffer_size(out_format, width, height, 1);
  
  buffer = (uint8_t*)av_malloc(num_bytes * sizeof(uint8_t));
  
  
  
  AVFrame* vid_frame = NULL;
  
  vid_frame = av_frame_alloc();
  
  AVFrame* conv_frame = NULL;
  
  conv_frame = av_frame_alloc();
  
  
  
  av_image_fill_arrays(conv_frame->data, conv_frame->linesize, buffer, 
  
                       out_format, width, height, 1);
  
  
  
  struct SwsContext *sws_ctx = NULL;
  
  sws_ctx = sws_getContext(width, height, cdc_ctx->pix_fmt,
  
                           width, height, out_format,
  
                           SWS_BILINEAR, NULL,NULL,NULL);
  
  
  
  int frame_num = 0;
  
  AVPacket vid_pckt;
  
  while (av_read_frame(fmt_ctx, &vid_pckt) >=0) {
  
      ret = avcodec_send_packet(cdc_ctx, &vid_pckt);
  
      if (ret < 0)
  
          break;
  
  
  
      ret = avcodec_receive_frame(cdc_ctx, vid_frame);
  
      if (ret < 0 && ret != AVERROR(EAGAIN) && ret != AVERROR_EOF)
  
          break;
  
      if (ret >= 0) {
  
          // convert image from native format to planar GBR
  
          sws_scale(sws_ctx, vid_frame->data, 
  
                    vid_frame->linesize, 0, vid_frame->height, 
  
                    conv_frame->data, conv_frame->linesize);
  
  
  
          unsigned char* r_ptr = output_arr + 
  
              (height * width * sizeof(unsigned char) * 3 * frame_num);
  
          unsigned char* g_ptr = r_ptr + (height * width * sizeof(unsigned char));
  
          unsigned char* b_ptr = g_ptr + (height * width * sizeof(unsigned char));
  
          unsigned int pxl_i = 0;
  
  
  
          for (unsigned int r = 0; r < height; ++r) {
  
              uint8_t* avframe_r = conv_frame->data[0] + r*conv_frame->linesize[0];
  
              for (unsigned int c = 0; c < width; ++c) {
  
                  r_ptr[pxl_i] = avframe_r[0];
  
                  g_ptr[pxl_i]   = avframe_r[1];
  
                  b_ptr[pxl_i]   = avframe_r[2];
  
                  avframe_r += 3;
  
                  ++pxl_i;
  
              }
  
          }
  
  
  
          ++frame_num;
  
  
  
          if (frame_num >= read_nframes)
  
              break;
  
      }
  
  }
  
  
  
  ...

  In my experience around two-thirds of the pixel values are different, each by +-1 (in a range of [0,255]). I am wondering is it due to some decoding scheme FFmpeg uses for reading JPEG frames ? I tried encoding and decoding png frames, and it works perfectly fine.

  In short my goal is to get the same pixel by pixel values for each JPEG frame as I would I have gotten if I was reading the JPEG images directly. Here is the stand-alone code I used. It includes cmake files to build code, and a couple of jpeg frames with the converted avi file to test this problem. (give —filetype png to test the png decoding).