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• getting black and white image after encoding

  16 mai 2012, par user1310596

  I am trying to encode image using ffmpeg library and objective c. I am using following code but I am getting black and white image as the result. Is there something to do with pixel format(PIX_FMT) ? Please help me so that I can get colored image.

  av_register_all();
  
  avcodec_init();
  
  avcodec_register_all();
  
  avformat_alloc_context();
  
  
  
  AVCodec *codec;
  
  AVCodecContext *ctx= NULL;
  
  int out_size, size, outbuf_size;
  
  AVFrame *picture;
  
  uint8_t *outbuf;
  
  unsigned char *flvdata = malloc(sizeof(unsigned char) * 30);
  
  
  
  
  
  outbuf_size = 200000;
  
  outbuf = malloc(outbuf_size);
  
  
  
  
  
  printf("Video encoding\n");
  
  
  
  codec = avcodec_find_encoder(CODEC_ID_FLV1);
  
  if (!codec) {
  
          fprintf(stderr, "codec not found\n");
  
          exit(1);
  
  }
  
  
  
  ctx= avcodec_alloc_context();
  
  picture= avcodec_alloc_frame();
  
  
  
  
  
  ctx->width = 320;
  
  ctx->height = 240;
  
  ctx -> sample_rate = 11025;
  
  ctx -> time_base.den = 1000;
  
  ctx -> time_base.num = 23976;
  
  ctx -> codec_id = CODEC_ID_FLV1;
  
  ctx -> codec_type = CODEC_TYPE_VIDEO;
  
  ctx->pix_fmt = PIX_FMT_YUV420P;
  
  
  
  if (avcodec_open(ctx, codec) < 0) {
  
          fprintf(stderr, "could not open codec\n");
  
          exit(1);
  
  }
  
  
  
  outbuf_size = 100000;
  
  outbuf = malloc(outbuf_size);
  
  size = ctx->width * ctx->height;
  
  
  
  AVFrame* outpic = avcodec_alloc_frame();
  
  int nbytes = avpicture_get_size(PIX_FMT_YUV420P, ctx->width, ctx->height);
  
  
  
  uint8_t* outbuffer = (uint8_t*)av_malloc(nbytes);
  
  
  
  fflush(stdout);
  
  
  
  int numBytes = avpicture_get_size(PIX_FMT_YUV420P, ctx->width, ctx->height);
  
  
  
  UIImage *image = [UIImage imageNamed:[NSString stringWithFormat:@"0.jpg"]];
  
  CGImageRef newCgImage = [image CGImage];
  
  
  
  CGDataProviderRef dataProvider = CGImageGetDataProvider(newCgImage);
  
  CFDataRef bitmapData = CGDataProviderCopyData(dataProvider);
  
  long dataLength = CFDataGetLength(bitmapData);
  
  
  
  uint8_t *buffer = (uint8_t *)av_malloc(dataLength);
  
  buffer = (uint8_t *)CFDataGetBytePtr(bitmapData);
  
  
  
  for(int i = 0; i < dataLength; i++)
  
  {
  
          if((i + 1) % 16 == 1 && i != 1)
  
                  printf("\n");
  
          printf("%X\t",buffer[i]); // getting something different than the     actual hex value of the image
  
  }
  
  
  
  
  
  
  
  outpic -> pts = 0;        
  
  
  
  avpicture_fill((AVPicture*)picture, buffer, PIX_FMT_RGB8, ctx->width, ctx->height);
  
  
  
  avpicture_fill((AVPicture*)outpic, outbuffer, PIX_FMT_YUV420P, ctx->width, ctx->height);
  
  
  
  struct SwsContext* fooContext = sws_getContext(ctx->width, ctx->height, 
  
                                                         PIX_FMT_RGB8, 
  
                                                         ctx->width, ctx->height, 
  
                                                         PIX_FMT_YUV420P, 
  
                                                         SWS_FAST_BILINEAR, NULL, NULL, NULL);
  
  
  
  sws_scale(fooContext, picture->data, picture->linesize, 0, ctx->height, outpic->data, outpic->linesize);
  
  
  
  printf("abcdefghijklmnop");
  
  out_size = avcodec_encode_video(ctx, outbuf, outbuf_size, outpic);
  
  printf("\n\n out_size %d   outbuf_size %d",out_size,outbuf_size);

  Thanks in advance

• Encoding video only FLV

  25 mars 2012, par NadavRub

  I am trying to generate a video only FLV file, I am using :

  1. libx264 + ffmpeg
  2. 30 fps ( fixed )
  3. playback is done using VLC 2.0.1 and flowplayer

  When playing the FLV the frame-rate seems 1 frame per sec, following is the way I cfg ffmpeg :

  AVOutputFormat* fmtOutput = av_oformat_next(0);
  
  while((0 != fmtOutput) && (0 != strcmp(fmtOutput->name, "flv")))
  
      fmtOutput = av_oformat_next(fmtOutput);
  
  m_pFmtCtxOutput          = avformat_alloc_context();
  
  m_pFmtCtxOutput->oformat = fmtOutput;
  
  
  
  AVStream* pOutVideoStream= av_new_stream(m_pFmtCtxOutput, pInVideoStream->id);
  
  AVCodec*  videoEncoder   = avcodec_find_encoder(CODEC_ID_H264);
  
  
  
  pOutVideoStream->codec->width    = 640;
  
  pOutVideoStream->codec->height   = 480;
  
  pOutVideoStream->codec->level    = 30;
  
  pOutVideoStream->codec->pix_fmt  = PIX_FMT_YUV420P;
  
  pOutVideoStream->codec->bit_rate = 3000000;
  
  
  
  pOutVideoStream->cur_dts         = 0;
  
  pOutVideoStream->first_dts       = 0;
  
  pOutVideoStream->index           = 0;
  
  pOutVideoStream->avg_frame_rate  = (AVRational){ 30, 1 };
  
  pOutVideoStream->time_base       =
  
  pOutVideoStream->codec->time_base= (AVRational){ 1, 30000 };
  
  pOutVideoStream->codec->gop_size = 30;
  
  %% Some specific libx264 settings %%
  
  m_dVideoStep                     = 1000;// packet dts/pts is incremented by this amount each frame
  
  
  
  pOutVideoStream->codec->flags   |= CODEC_FLAG_GLOBAL_HEADER;
  
  avcodec_open(pOutVideoStream->codec, videoEncoder);

  The resulting file seems OK, with the exception of the playback frame-rate.
  having in mind that :

  1. pOutVideoStream->avg_frame_rate = (AVRational) 30, 1  ;
  2. pOutVideoStream->time_base = (AVRational) 1, 30000  ;
  3. pOutVideoStream->codec->time_base= (AVRational) 1, 30000  ;
  4. For each frame I increment the dts/pts by 1000

  What am I doing wrong here ? why the file is playing choppy ( 1 fps ) ?

  Any help will be appreciated.

  Nadav at Sophin

• Encoding video only FLV

  25 mars 2012, par NadavRub

  I am trying to generate a video only FLV file, I am using :

  1. libx264 + ffmpeg
  2. 30 fps ( fixed )
  3. playback is done using VLC 2.0.1 and flowplayer

  When playing the FLV the frame-rate seems 1 frame per sec, following is the way I cfg ffmpeg :

  AVOutputFormat* fmtOutput = av_oformat_next(0);
  
  while((0 != fmtOutput) && (0 != strcmp(fmtOutput->name, "flv")))
  
      fmtOutput = av_oformat_next(fmtOutput);
  
  m_pFmtCtxOutput          = avformat_alloc_context();
  
  m_pFmtCtxOutput->oformat = fmtOutput;
  
  
  
  AVStream* pOutVideoStream= av_new_stream(m_pFmtCtxOutput, pInVideoStream->id);
  
  AVCodec*  videoEncoder   = avcodec_find_encoder(CODEC_ID_H264);
  
  
  
  pOutVideoStream->codec->width    = 640;
  
  pOutVideoStream->codec->height   = 480;
  
  pOutVideoStream->codec->level    = 30;
  
  pOutVideoStream->codec->pix_fmt  = PIX_FMT_YUV420P;
  
  pOutVideoStream->codec->bit_rate = 3000000;
  
  
  
  pOutVideoStream->cur_dts         = 0;
  
  pOutVideoStream->first_dts       = 0;
  
  pOutVideoStream->index           = 0;
  
  pOutVideoStream->avg_frame_rate  = (AVRational){ 30, 1 };
  
  pOutVideoStream->time_base       =
  
  pOutVideoStream->codec->time_base= (AVRational){ 1, 30000 };
  
  pOutVideoStream->codec->gop_size = 30;
  
  %% Some specific libx264 settings %%
  
  m_dVideoStep                     = 1000;// packet dts/pts is incremented by this amount each frame
  
  
  
  pOutVideoStream->codec->flags   |= CODEC_FLAG_GLOBAL_HEADER;
  
  avcodec_open(pOutVideoStream->codec, videoEncoder);

  The resulting file seems OK, with the exception of the playback frame-rate.
  having in mind that :

  1. pOutVideoStream->avg_frame_rate = (AVRational) 30, 1  ;
  2. pOutVideoStream->time_base = (AVRational) 1, 30000  ;
  3. pOutVideoStream->codec->time_base= (AVRational) 1, 30000  ;
  4. For each frame I increment the dts/pts by 1000

  What am I doing wrong here ? why the file is playing choppy ( 1 fps ) ?

  Any help will be appreciated.

  Nadav at Sophin