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• swscaler@0dd9e620 : deprecated pixel format used, make sure you did set range correctly"

  19 juin 2015, par Tariq

  I am decoding RTSP video stream with FFMpeg.
  At display time (call to cv::imshow(...)), I get the following exception :

  [swscaler @ 0d55e5c0] deprecated pixel format used, make sure you did
  set range correctly

  I am converting the pixel format from "AV_PIX_FMT_YUVJ420P" to "AV_PIX_FMT_YUV420P". Still getting the above exception. Any help is appreciated ;

  int Decodestream()
  
  {
  
      av_register_all();
  
      avdevice_register_all();
  
      avcodec_register_all();
  
      avformat_network_init();
  
  
  
      const char  *filenameSrc = "rtsp://192.168.1.67/gnz_media/second";
  
  
  
      AVCodecContext  *pCodecCtx;
  
      AVFormatContext *pFormatCtx = avformat_alloc_context();
  
  
  
      AVCodec * pCodec;
  
      AVFrame *pFrame, *pFrameRGB;
  
  
  
      if(avformat_open_input(&pFormatCtx,filenameSrc,NULL,NULL) != 0)
  
      {return -1;}
  
  
  
      if(av_find_stream_info(pFormatCtx) < 0)   
  
      {return -1;}
  
  
  
      av_dump_format(pFormatCtx, 0, filenameSrc, 0);
  
  
  
      int videoStream = 1;
  
  
  
      for(int i=0; i < pFormatCtx->nb_streams; i++)
  
      {
  
          if(pFormatCtx->streams[i]->codec->coder_type==AVMEDIA_TYPE_VIDEO)
  
          {
  
              videoStream = i;
  
              break;
  
          }
  
      }
  
  
  
      if(videoStream == -1) return -1 ;
  
  
  
      pCodecCtx = pFormatCtx->streams[videoStream]->codec;
  
  
  
      pCodec =avcodec_find_decoder(pCodecCtx->codec_id);
  
  
  
      if(pCodec==NULL)
  
      {return -1;} //codec not found
  
  
  
      if(avcodec_open2(pCodecCtx,pCodec,NULL) < 0)
  
      { return -1;}
  
  
  
      pFrame    = avcodec_alloc_frame();
  
      pFrameRGB = avcodec_alloc_frame();
  
  
  
      uint8_t *buffer;
  
  
  
      int numBytes;
  
  
  
      AVPixelFormat  pFormat;
  
  
  
      switch (pFormatCtx->streams[videoStream]->codec->pix_fmt) 
  
      {
  
      case AV_PIX_FMT_YUVJ420P : pFormat = AV_PIX_FMT_YUV420P; break;
  
      case AV_PIX_FMT_YUVJ422P : pFormat = AV_PIX_FMT_YUV422P; break;
  
      case AV_PIX_FMT_YUVJ444P : pFormat = AV_PIX_FMT_YUV444P; break;
  
      case AV_PIX_FMT_YUVJ440P : pFormat = AV_PIX_FMT_YUV440P; 
  
      default:
  
          pFormat = pFormatCtx->streams[videoStream]->codec->pix_fmt;
  
          break;
  
      }
  
  
  
      numBytes = avpicture_get_size(pFormat,pCodecCtx->width,pCodecCtx->height) ; 
  
  
  
      buffer = (uint8_t *) av_malloc(numBytes*sizeof(uint8_t));
  
  
  
      avpicture_fill((AVPicture *) pFrameRGB,buffer,pFormat,pCodecCtx->width,pCodecCtx->height);
  
  
  
      int res, frameFinished;
  
  
  
      AVPacket packet;
  
  
  
      while(res = av_read_frame(pFormatCtx,&packet)>=0)
  
      {
  
  
  
          if(packet.stream_index == videoStream){
  
  
  
              avcodec_decode_video2(pCodecCtx,pFrame,&frameFinished,&packet);
  
  
  
              if(frameFinished){
  
  
  
                  struct SwsContext * img_convert_ctx;
  
  
  
                  img_convert_ctx = sws_getCachedContext(NULL,pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt,   pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_BGR24, SWS_BICUBIC, NULL, NULL,NULL);
  
  
  
                  sws_scale(img_convert_ctx, ((AVPicture*)pFrame)->data, ((AVPicture*)pFrame)->linesize, 0, pCodecCtx->height, ((AVPicture *)pFrameRGB)->data, ((AVPicture *)pFrameRGB)->linesize);
  
  
  
                  cv::Mat img(pFrame->height,pFrame->width,CV_8UC3,pFrameRGB->data[0]);
  
                  cv::imshow("display",img);
  
                  cvWaitKey(10);          
  
              }
  
          }
  
  
  
      }
  
      //Memory clean up code goes here 
  
  }

• "only position independent executables (PIE) are supported" error in FFMPEG Android Lollipop

  2 juin 2015, par Karthikeyan

  I am using FFMPEG support library to convert bunch of images to video. It works fine on earlier version of the android lollipop. But in the lollipop it generates the following error. ***error: only position independent executables (PIE) are supported.*** I know the PIE Security restrictions has been changed in lollipop, but i don’t know how to fix it.

  From my knowledge it may have two possible solutions,

  either

  we need to relocate the FFMPEG library assets to the SDCard and we have to refer them from our coding, if this is the answer what are all the steps to be followed ?

  or

  Is there any update in the FFMPEG library for android lollipop.

  If both are wrong can you provide me with the proper solution.

  Many thanks...

  Here is my code

     try {
  
              Log.e(LOGTAG, "started");
  
  
  
              String[] ffmpegCommand = {"/data/data/com.mobvcasting.mjpegffmpeg/ffmpeg", "-r", ""+p.getPreviewFrameRate(), "-b", "1000000", "-vcodec", "mjpeg", "-i", 
  
                      Environment.getExternalStorageDirectory().getPath() + "/req_images/frame_%05d.jpg", Environment.getExternalStorageDirectory().getPath() + "/req_images/video.mov"};
  
  
  
              ffmpegProcess = new ProcessBuilder(ffmpegCommand).redirectErrorStream(true).start();            
  
  
  
              OutputStream ffmpegOutStream = ffmpegProcess.getOutputStream();
  
              BufferedReader reader = new BufferedReader(new InputStreamReader(ffmpegProcess.getInputStream()));
  
  
  
              String line;
  
  
  
              Log.v(LOGTAG,"***Starting FFMPEG***");
  
              while ((line = reader.readLine()) != null)
  
              {
  
                  Log.v(LOGTAG,"***"+line+"***");
  
              }
  
              Log.v(LOGTAG,"***Ending FFMPEG***");
  
  
  
  
  
          } catch (IOException e) {
  
              e.printStackTrace();
  
          }
  
  
  
          if (ffmpegProcess != null) {
  
              ffmpegProcess.destroy();        
  
          }
  
          Log.e(LOGTAG, "Background done");

• FFmpeg how to apply "aac_adtstoasc" and "h264_mp4toannexb" bitstream filters to transcode to h.264 with AAC

  9 juillet 2015, par larod

  I’ve been struggling with this issue for about a month, I have studied FFmpeg documentation more specifically transcode_aac.c, transcoding.c, decoding_encoding.c and Handbrake’s implementation which is really dense.

  The error that I’m getting is the following : [mp4 @ 0x11102f800] Malformed AAC bitstream detected: use the audio bitstream filter 'aac_adtstoasc' to fix it ('-bsf:a aac_adtstoasc' option with ffmpeg).

  The research I’ve done points to a filter that needs to be implemented.

  FIX:AAC in some container format (FLV, MP4, MKV etc.) need "aac_adtstoasc" bitstream filter (BSF).

  I know I can do the following :

  AVBitStreamFilterContext* aacbsfc =  av_bitstream_filter_init("aac_adtstoasc");

  And then do something like this :

  av_bitstream_filter_filter(aacbsfc, in_stream->codec, NULL, &pkt.data, &pkt.size, pkt.data, pkt.size, 0);

  What eludes me is when to filter the AVPacket, is it before calling av_packet_rescale_ts or inside init_filter. I would greatly appreciate if someone can point me in the right direction. Thanks in advance.

  // Variables
  
  AVFormatContext *_ifmt_ctx, *_ofmt_ctx;
  
  FilteringContext *_filter_ctx;
  
  AVBitStreamFilterContext *_h264bsfc;
  
  AVBitStreamFilterContext *_aacbsfc;
  
  NSURL *_srcURL, *_dstURL;
  
  
  
   - (IBAction)trancode:(id)sender {
  
          NSLog(@"%s %@",__func__, _mediaFile.fsName);
  
          int ret, got_frame;
  
          int (*dec_func)(AVCodecContext *, AVFrame *, int *, const AVPacket *);
  
          unsigned int stream_index, i;
  
          enum AVMediaType type;
  
          AVPacket packet = {.data = NULL, .size = 0};
  
          AVFrame *frame = NULL;
  
          _h264bsfc = av_bitstream_filter_init("h264_mp4toannexb");
  
          _aacbsfc =  av_bitstream_filter_init("aac_adtstoasc");
  
  
  
      _srcURL = [Utility urlFromBookmark:_mediaFile.bookmark];
  
      if ([_srcURL startAccessingSecurityScopedResource]) {
  
          NSString *newFileName = [[_srcURL.lastPathComponent stringByDeletingPathExtension]stringByAppendingPathExtension:@"mp4"];
  
          _dstURL = [NSURL fileURLWithPath:[[_srcURL URLByDeletingLastPathComponent]URLByAppendingPathComponent:newFileName].path isDirectory:NO];
  
  
  
          [AppDelegate ffmpegRegisterAll];
  
  
  
          ret = open_input_file(_srcURL.path.fileSystemRepresentation);
  
          if (ret < 0) {
  
              NSLog(@"Error openning input file.");
  
          }
  
  
  
          ret = open_output_file(_dstURL.path.fileSystemRepresentation);
  
          if (ret < 0) {
  
              NSLog(@"Error openning output file.");
  
          }
  
  
  
          ret = init_filters();
  
          if (ret < 0) {
  
              NSLog(@"Error initializing filters.");
  
          }
  
  
  
          AVBitStreamFilterContext *h264bsfc = av_bitstream_filter_init("h264_mp4toannexb");
  
          AVBitStreamFilterContext* aacbsfc =  av_bitstream_filter_init("aac_adtstoasc");
  
          // Transcode *******************************************************************************
  
          while (1) {
  
              if ((ret = av_read_frame(_ifmt_ctx, &packet)) < 0) {
  
                  break;
  
              }
  
              stream_index = packet.stream_index;
  
              type = _ifmt_ctx->streams[packet.stream_index]->codec->codec_type;
  
              av_log(NULL, AV_LOG_DEBUG, "Demuxer gave frame of stream_index %u\n", stream_index);
  
  
  
  
  
  
  
              if (_filter_ctx[stream_index].filter_graph) {
  
                  av_log(NULL, AV_LOG_DEBUG, "Going to reencode&filter the frame\n");
  
                  frame = av_frame_alloc();
  
                  if (!frame) {
  
                      ret = AVERROR(ENOMEM);
  
                      break;
  
                  }
  
  
  
                  av_packet_rescale_ts(&packet, _ifmt_ctx->streams[stream_index]->time_base, _ifmt_ctx->streams[stream_index]->codec->time_base);
  
                  dec_func = (type == AVMEDIA_TYPE_VIDEO) ? avcodec_decode_video2 : avcodec_decode_audio4;
  
                  ret = dec_func(_ifmt_ctx->streams[stream_index]->codec, frame, &got_frame, &packet);
  
                  if (ret < 0) {
  
                      av_frame_free(&frame);
  
                      av_log(NULL, AV_LOG_ERROR, "Decoding failed\n");
  
                      break;
  
                  }
  
  
  
                  if (got_frame) {
  
                      frame->pts = av_frame_get_best_effort_timestamp(frame);
  
                      ret = filter_encode_write_frame(frame, stream_index);
  
                      av_frame_free(&frame);
  
                      if (ret < 0)
  
                          goto end;
  
                  } else {
  
                      av_frame_free(&frame);
  
                  }
  
              } else {
  
                  /* remux this frame without reencoding */
  
                  av_packet_rescale_ts(&packet,
  
                                       _ifmt_ctx->streams[stream_index]->time_base,
  
                                       _ofmt_ctx->streams[stream_index]->time_base);
  
  
  
                  ret = av_interleaved_write_frame(_ofmt_ctx, &packet);
  
                  if (ret < 0)
  
                      goto end;
  
              }
  
              av_free_packet(&packet);
  
          }
  
          // *****************************************************************************************
  
  
  
          /* flush filters and encoders */
  
          for (i = 0; i < _ifmt_ctx->nb_streams; i++) {
  
              /* flush filter */
  
              if (!_filter_ctx[i].filter_graph)
  
                  continue;
  
              ret = filter_encode_write_frame(NULL, i);
  
              if (ret < 0) {
  
                  av_log(NULL, AV_LOG_ERROR, "Flushing filter failed\n");
  
                  goto end;
  
              }
  
  
  
              /* flush encoder */
  
              ret = flush_encoder(i);
  
              if (ret < 0) {
  
                  av_log(NULL, AV_LOG_ERROR, "Flushing encoder failed\n");
  
                  goto end;
  
              }
  
          }
  
          av_write_trailer(_ofmt_ctx);
  
          av_bitstream_filter_close(h264bsfc);
  
          av_bitstream_filter_close(aacbsfc);
  
      } else {
  
          NSLog(@"Unable to resolve url for %@",_mediaFile.url.lastPathComponent);
  
      }
  
      [_srcURL stopAccessingSecurityScopedResource];
  
  
  
  end:
  
      av_free_packet(&packet);
  
      av_frame_free(&frame);
  
      for (i = 0; i < _ifmt_ctx->nb_streams; i++) {
  
          avcodec_close(_ifmt_ctx->streams[i]->codec);
  
          if (_ofmt_ctx && _ofmt_ctx->nb_streams > i && _ofmt_ctx->streams[i] && _ofmt_ctx->streams[i]->codec)
  
              avcodec_close(_ofmt_ctx->streams[i]->codec);
  
          if (_filter_ctx && _filter_ctx[i].filter_graph)
  
              avfilter_graph_free(&_filter_ctx[i].filter_graph);
  
      }
  
      av_free(_filter_ctx);
  
      avformat_close_input(&_ifmt_ctx);
  
      if (_ofmt_ctx && !(_ofmt_ctx->oformat->flags & AVFMT_NOFILE))
  
          avio_closep(&_ofmt_ctx->pb);
  
      avformat_free_context(_ofmt_ctx);
  
  }

  The following method is used to open the input file and create the ifmt_ctx.

  int open_input_file(const char *filename) {
  
      int ret;
  
      unsigned int i;
  
  
  
      _ifmt_ctx = NULL;
  
      if ((ret = avformat_open_input(&_ifmt_ctx, filename, NULL, NULL)) < 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
  
          return ret;
  
      }
  
  
  
      if ((ret = avformat_find_stream_info(_ifmt_ctx, NULL)) < 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
  
          return ret;
  
      }
  
  
  
      for (i = 0; i < _ifmt_ctx->nb_streams; i++) {
  
          AVStream *stream;
  
          AVCodecContext *codec_ctx;
  
          stream = _ifmt_ctx->streams[i];
  
          codec_ctx = stream->codec;
  
          /* Reencode video & audio and remux subtitles etc. */
  
          if (codec_ctx->codec_type == AVMEDIA_TYPE_VIDEO
  
              || codec_ctx->codec_type == AVMEDIA_TYPE_AUDIO) {
  
              /* Open decoder */
  
              ret = avcodec_open2(codec_ctx,
  
                                  avcodec_find_decoder(codec_ctx->codec_id), NULL);
  
              if (ret < 0) {
  
                  av_log(NULL, AV_LOG_ERROR, "Failed to open decoder for stream #%u\n", i);
  
                  return ret;
  
              }
  
          }
  
      }
  
  
  
      // Remove later
  
      av_dump_format(_ifmt_ctx, 0, filename, 0);
  
      return 0;
  
  }

  This method is used to open the output file and create the output format context.

  int open_output_file(const char *filename) {
  
      AVStream *out_stream;
  
      AVStream *in_stream;
  
      AVCodecContext *dec_ctx, *enc_ctx;
  
      AVCodec *encoder;
  
      int ret;
  
      unsigned int i;
  
  
  
      _ofmt_ctx = NULL;
  
      avformat_alloc_output_context2(&_ofmt_ctx, NULL, NULL, filename);
  
      if (!_ofmt_ctx) {
  
          av_log(NULL, AV_LOG_ERROR, "Could not create output context\n");
  
          return AVERROR_UNKNOWN;
  
      }
  
  
  
  
  
      for (i = 0; i < _ifmt_ctx->nb_streams; i++) {
  
          out_stream = avformat_new_stream(_ofmt_ctx, NULL);
  
          if (!out_stream) {
  
              av_log(NULL, AV_LOG_ERROR, "Failed allocating output stream\n");
  
              return AVERROR_UNKNOWN;
  
          }
  
  
  
          in_stream = _ifmt_ctx->streams[i];
  
          dec_ctx = in_stream->codec;
  
          enc_ctx = out_stream->codec;
  
  
  
          if (dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO) {
  
              // set video stream
  
              encoder = avcodec_find_encoder(AV_CODEC_ID_H264);
  
              avcodec_get_context_defaults3(enc_ctx, encoder);
  
              av_opt_set(enc_ctx->priv_data, "preset", "slow", 0);
  
              enc_ctx->height = dec_ctx->height;
  
              enc_ctx->width = dec_ctx->width;
  
              enc_ctx->bit_rate = dec_ctx->bit_rate;
  
              enc_ctx->time_base = out_stream->time_base = dec_ctx->time_base;
  
              enc_ctx->pix_fmt = encoder->pix_fmts[0];
  
  
  
              ret = avcodec_open2(enc_ctx, encoder, NULL);
  
              if (ret < 0) {
  
                  av_log(NULL, AV_LOG_ERROR, "Cannot open video encoder for stream #%u\n", i);
  
                  return ret;
  
              }
  
  
  
          } else if (dec_ctx->codec_type == AVMEDIA_TYPE_AUDIO) {
  
              // set audio stream
  
              //encoder = avcodec_find_encoder(AV_CODEC_ID_AAC);
  
              encoder = avcodec_find_encoder_by_name("libfdk_aac");
  
              avcodec_get_context_defaults3(enc_ctx, encoder);
  
              enc_ctx->profile = FF_PROFILE_AAC_HE_V2;
  
              enc_ctx->sample_rate = dec_ctx->sample_rate;
  
              enc_ctx->channel_layout = dec_ctx->channel_layout;
  
              enc_ctx->channels = av_get_channel_layout_nb_channels(enc_ctx->channel_layout);
  
              enc_ctx->sample_fmt = encoder->sample_fmts[0];
  
              enc_ctx->time_base = out_stream->time_base = (AVRational){1, enc_ctx->sample_rate};
  
              enc_ctx->bit_rate = dec_ctx->bit_rate;
  
  
  
              ret = avcodec_open2(enc_ctx, encoder, NULL);
  
              if (ret < 0) {
  
                  av_log(NULL, AV_LOG_ERROR, "Cannot open video encoder for stream #%u\n", i);
  
                  return ret;
  
              }
  
  
  
          } else if (dec_ctx->codec_type == AVMEDIA_TYPE_UNKNOWN) {
  
              // deal with error
  
              av_log(NULL, AV_LOG_FATAL, "Elementary stream #%d is of unknown type, cannot proceed\n", i);
  
              return AVERROR_INVALIDDATA;
  
          } else {
  
              // remux stream
  
              ret = avcodec_copy_context(_ofmt_ctx->streams[i]->codec,
  
                                         _ifmt_ctx->streams[i]->codec);
  
              if (ret < 0) {
  
                  av_log(NULL, AV_LOG_ERROR, "Copying stream context failed\n");
  
                  return ret;
  
              }
  
          }
  
  
  
          if (_ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER) {
  
              enc_ctx->flags |= CODEC_FLAG_GLOBAL_HEADER;
  
          }
  
      }
  
  
  
      av_dump_format(_ofmt_ctx, 0, filename, 1);
  
  
  
      NSURL *openFileURL = [Utility openPanelAt:[NSURL URLWithString:_dstURL.URLByDeletingLastPathComponent.path]
  
                                      withTitle:@"Transcode File"
  
                                        message:@"Please allow Maví to create the new file."
  
                                      andPrompt:@"Grant Access"];
  
  
  
      openFileURL = [openFileURL URLByAppendingPathComponent:_dstURL.lastPathComponent isDirectory:NO];
  
      if (!(_ofmt_ctx->oformat->flags & AVFMT_NOFILE)) {
  
          ret = avio_open(&_ofmt_ctx->pb, openFileURL.fileSystemRepresentation, AVIO_FLAG_WRITE);
  
          if (ret < 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Could not open output file '%s'", filename);
  
              return ret;
  
          }
  
      }
  
  
  
      /* init muxer, write output file header */
  
      ret = avformat_write_header(_ofmt_ctx, NULL);
  
      if (ret < 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Error occurred when opening output file\n");
  
          return ret;
  
      }
  
  
  
      return 0;
  
  }

  These two methods deal with initialising the filters and filtering.

  int init_filters(void) {
  
      const char *filter_spec;
  
      unsigned int i;
  
      int ret;
  
      _filter_ctx = av_malloc_array(_ifmt_ctx->nb_streams, sizeof(*_filter_ctx));
  
      if (!_filter_ctx)
  
          return AVERROR(ENOMEM);
  
  
  
      for (i = 0; i < _ifmt_ctx->nb_streams; i++) {
  
          _filter_ctx[i].buffersrc_ctx  = NULL;
  
          _filter_ctx[i].buffersink_ctx = NULL;
  
          _filter_ctx[i].filter_graph   = NULL;
  
          if (!(_ifmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO
  
                || _ifmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO))
  
              continue;
  
  
  
  
  
          if (_ifmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
  
              filter_spec = "null"; /* passthrough (dummy) filter for video */
  
          else
  
              filter_spec = "anull"; /* passthrough (dummy) filter for audio */
  
          ret = init_filter(&_filter_ctx[i], _ifmt_ctx->streams[i]->codec,
  
                            _ofmt_ctx->streams[i]->codec, filter_spec);
  
          if (ret)
  
              return ret;
  
      }
  
      return 0;
  
  }
  
  int init_filter(FilteringContext* fctx, AVCodecContext *dec_ctx, AVCodecContext *enc_ctx, const char *filter_spec) {
  
      char args[512];
  
      int ret = 0;
  
      AVFilter *buffersrc = NULL;
  
      AVFilter *buffersink = NULL;
  
      AVFilterContext *buffersrc_ctx = NULL;
  
      AVFilterContext *buffersink_ctx = NULL;
  
      AVFilterInOut *outputs = avfilter_inout_alloc();
  
      AVFilterInOut *inputs  = avfilter_inout_alloc();
  
      AVFilterGraph *filter_graph = avfilter_graph_alloc();
  
  
  
      if (!outputs || !inputs || !filter_graph) {
  
          ret = AVERROR(ENOMEM);
  
          goto end;
  
      }
  
  
  
      if (dec_ctx->codec_type == AVMEDIA_TYPE_VIDEO) {
  
          buffersrc = avfilter_get_by_name("buffer");
  
          buffersink = avfilter_get_by_name("buffersink");
  
          if (!buffersrc || !buffersink) {
  
              av_log(NULL, AV_LOG_ERROR, "filtering source or sink element not found\n");
  
              ret = AVERROR_UNKNOWN;
  
              goto end;
  
          }
  
  
  
          snprintf(args, sizeof(args),
  
                   "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
  
                   dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,
  
                   dec_ctx->time_base.num, dec_ctx->time_base.den,
  
                   dec_ctx->sample_aspect_ratio.num,
  
                   dec_ctx->sample_aspect_ratio.den);
  
  
  
          ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
  
                                             args, NULL, filter_graph);
  
          if (ret < 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
  
              goto end;
  
          }
  
  
  
          ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
  
                                             NULL, NULL, filter_graph);
  
          if (ret < 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
  
              goto end;
  
          }
  
  
  
          ret = av_opt_set_bin(buffersink_ctx, "pix_fmts",
  
                               (uint8_t*)&enc_ctx->pix_fmt, sizeof(enc_ctx->pix_fmt),
  
                               AV_OPT_SEARCH_CHILDREN);
  
          if (ret < 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Cannot set output pixel format\n");
  
              goto end;
  
          }
  
      } else if (dec_ctx->codec_type == AVMEDIA_TYPE_AUDIO) {
  
          buffersrc = avfilter_get_by_name("abuffer");
  
          buffersink = avfilter_get_by_name("abuffersink");
  
          if (!buffersrc || !buffersink) {
  
              av_log(NULL, AV_LOG_ERROR, "filtering source or sink element not found\n");
  
              ret = AVERROR_UNKNOWN;
  
              goto end;
  
          }
  
  
  
          if (!dec_ctx->channel_layout)
  
              dec_ctx->channel_layout =
  
              av_get_default_channel_layout(dec_ctx->channels);
  
          snprintf(args, sizeof(args),
  
                   "time_base=%d/%d:sample_rate=%d:sample_fmt=%s:channel_layout=0x%"PRIx64,
  
                   dec_ctx->time_base.num, dec_ctx->time_base.den, dec_ctx->sample_rate,
  
                   av_get_sample_fmt_name(dec_ctx->sample_fmt),
  
                   dec_ctx->channel_layout);
  
          ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
  
                                             args, NULL, filter_graph);
  
          if (ret < 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Cannot create audio buffer source\n");
  
              goto end;
  
          }
  
  
  
          ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
  
                                             NULL, NULL, filter_graph);
  
          if (ret < 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Cannot create audio buffer sink\n");
  
              goto end;
  
          }
  
  
  
          ret = av_opt_set_bin(buffersink_ctx, "sample_fmts",
  
                               (uint8_t*)&enc_ctx->sample_fmt, sizeof(enc_ctx->sample_fmt),
  
                               AV_OPT_SEARCH_CHILDREN);
  
          if (ret < 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Cannot set output sample format\n");
  
              goto end;
  
          }
  
  
  
          ret = av_opt_set_bin(buffersink_ctx, "channel_layouts",
  
                               (uint8_t*)&enc_ctx->channel_layout,
  
                               sizeof(enc_ctx->channel_layout), AV_OPT_SEARCH_CHILDREN);
  
          if (ret < 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Cannot set output channel layout\n");
  
              goto end;
  
          }
  
  
  
          ret = av_opt_set_bin(buffersink_ctx, "sample_rates",
  
                               (uint8_t*)&enc_ctx->sample_rate, sizeof(enc_ctx->sample_rate),
  
                               AV_OPT_SEARCH_CHILDREN);
  
          if (ret < 0) {
  
              av_log(NULL, AV_LOG_ERROR, "Cannot set output sample rate\n");
  
              goto end;
  
          }
  
      } else {
  
          ret = AVERROR_UNKNOWN;
  
          goto end;
  
      }
  
  
  
      /* Endpoints for the filter graph. */
  
      outputs->name       = av_strdup("in");
  
      outputs->filter_ctx = buffersrc_ctx;
  
      outputs->pad_idx    = 0;
  
      outputs->next       = NULL;
  
  
  
      inputs->name       = av_strdup("out");
  
      inputs->filter_ctx = buffersink_ctx;
  
      inputs->pad_idx    = 0;
  
      inputs->next       = NULL;
  
  
  
      if (!outputs->name || !inputs->name) {
  
          ret = AVERROR(ENOMEM);
  
          goto end;
  
      }
  
  
  
      if ((ret = avfilter_graph_parse_ptr(filter_graph, filter_spec,
  
                                          &inputs, &outputs, NULL)) < 0)
  
          goto end;
  
  
  
      if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
  
          goto end;
  
  
  
      /* Fill FilteringContext */
  
      fctx->buffersrc_ctx = buffersrc_ctx;
  
      fctx->buffersink_ctx = buffersink_ctx;
  
      fctx->filter_graph = filter_graph;
  
  
  
  end:
  
      avfilter_inout_free(&inputs);
  
      avfilter_inout_free(&outputs);
  
  
  
      return ret;
  
  }

  Finally these two methods take care of writing the frames.

  int encode_write_frame(AVFrame *filt_frame, unsigned int stream_index, int *got_frame) {
  
      int ret;
  
      int got_frame_local;
  
      AVPacket enc_pkt;
  
      int (*enc_func)(AVCodecContext *, AVPacket *, const AVFrame *, int *) =
  
      (_ifmt_ctx->streams[stream_index]->codec->codec_type ==
  
       AVMEDIA_TYPE_VIDEO) ? avcodec_encode_video2 : avcodec_encode_audio2;
  
  
  
      if (!got_frame)
  
          got_frame = &got_frame_local;
  
  
  
      av_log(NULL, AV_LOG_INFO, "Encoding frame\n");
  
      /* encode filtered frame */
  
      enc_pkt.data = NULL;
  
      enc_pkt.size = 0;
  
      av_init_packet(&enc_pkt);
  
      ret = enc_func(_ofmt_ctx->streams[stream_index]->codec, &enc_pkt,
  
                     filt_frame, got_frame);
  
      av_frame_free(&filt_frame);
  
      if (ret < 0)
  
          return ret;
  
      if (!(*got_frame))
  
          return 0;
  
  
  
      /* prepare packet for muxing */
  
      enc_pkt.stream_index = stream_index;
  
      av_packet_rescale_ts(&enc_pkt,
  
                           _ofmt_ctx->streams[stream_index]->codec->time_base,
  
                           _ofmt_ctx->streams[stream_index]->time_base);
  
  
  
      av_log(NULL, AV_LOG_DEBUG, "Muxing frame\n");
  
      /* mux encoded frame */
  
      ret = av_interleaved_write_frame(_ofmt_ctx, &enc_pkt);
  
      return ret;
  
  }
  
  int filter_encode_write_frame(AVFrame *frame, unsigned int stream_index)
  
  {
  
      int ret;
  
      AVFrame *filt_frame;
  
  
  
      av_log(NULL, AV_LOG_INFO, "Pushing decoded frame to filters\n");
  
      /* push the decoded frame into the filtergraph */
  
      ret = av_buffersrc_add_frame_flags(_filter_ctx[stream_index].buffersrc_ctx,
  
                                         frame, 0);
  
      if (ret < 0) {
  
          av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");
  
          return ret;
  
      }
  
  
  
      /* pull filtered frames from the filtergraph */
  
      while (1) {
  
          filt_frame = av_frame_alloc();
  
          if (!filt_frame) {
  
              ret = AVERROR(ENOMEM);
  
              break;
  
          }
  
          av_log(NULL, AV_LOG_INFO, "Pulling filtered frame from filters\n");
  
          ret = av_buffersink_get_frame(_filter_ctx[stream_index].buffersink_ctx,
  
                                        filt_frame);
  
          if (ret < 0) {
  
              /* if no more frames for output - returns AVERROR(EAGAIN)
  
               * if flushed and no more frames for output - returns AVERROR_EOF
  
               * rewrite retcode to 0 to show it as normal procedure completion
  
               */
  
              if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
  
                  ret = 0;
  
              av_frame_free(&filt_frame);
  
              break;
  
          }
  
  
  
          filt_frame->pict_type = AV_PICTURE_TYPE_NONE;
  
          ret = encode_write_frame(filt_frame, stream_index, NULL);
  
          if (ret < 0)
  
              break;
  
      }
  
  
  
      return ret;
  
  }