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• avcodec, avutil : allow more control about how samples are skipped

  27 septembre 2014, par wm4

  avcodec, avutil : allow more control about how samples are skipped
  Add CODEC_FLAG2_SKIP_MANUAL (exposed as "skip_manual"), which makes
  
  the decoder export sample skip information via side data, instead
  
  of applying it automatically. The format of the side data is the
  
  same as AV_PKT_DATA_SKIP_SAMPLES, but since AVPacket and AVFrame
  
  side data constants overlap, AV_FRAME_DATA_SKIP_SAMPLES needs to
  
  be introduced.
  This is useful for applications which want to do the timestamp
  
  calculations manually, or which actually want to retrieve the
  
  padding.
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] doc/APIchanges
  • [DH] libavcodec/avcodec.h
  • [DH] libavcodec/options_table.h
  • [DH] libavcodec/utils.c
  • [DH] libavcodec/version.h
  • [DH] libavutil/frame.h
  • [DH] libavutil/version.h

• iPhone - A problem with decoding H264 using ffmpeg

  25 mars 2012, par HAPPY_TIGER

  I am working with ffmpeg to decode H264 stream from server.

  I referenced DecoderWrapper from http://github.com/dropcam/dropcam_for_iphone.

  I compiled it successfully, but I don't know how use it.

  Here are the function that has problem.

  - (id)initWithCodec:(enum VideoCodecType)codecType 
  
           colorSpace:(enum VideoColorSpace)colorSpace 
  
                width:(int)width 
  
               height:(int)height 
  
          privateData:(NSData*)privateData {
  
      if(self = [super init]) {
  
  
  
          codec = avcodec_find_decoder(CODEC_ID_H264);
  
          codecCtx = avcodec_alloc_context();
  
  
  
          // Note: for H.264 RTSP streams, the width and height are usually not specified (width and height are 0).  
  
          // These fields will become filled in once the first frame is decoded and the SPS is processed.
  
          codecCtx->width = width;
  
          codecCtx->height = height;
  
  
  
          codecCtx->extradata = av_malloc([privateData length]);
  
          codecCtx->extradata_size = [privateData length];
  
          [privateData getBytes:codecCtx->extradata length:codecCtx->extradata_size];
  
          codecCtx->pix_fmt = PIX_FMT_YUV420P;
  
  #ifdef SHOW_DEBUG_MV
  
          codecCtx->debug_mv = 0xFF;
  
  #endif
  
  
  
          srcFrame = avcodec_alloc_frame();
  
          dstFrame = avcodec_alloc_frame();
  
  
  
          int res = avcodec_open(codecCtx, codec);
  
          if (res < 0)
  
          {
  
              NSLog(@"Failed to initialize decoder");
  
          }
  
      }
  
  
  
      return self;    
  
  }

  What is the privateData parameter of this function ? I don't know how to set the parameter...

  Now avcodec_decode_video2 returns -1 ;

  The framedata is coming successfully.

  How solve this problem.

  Thanks a lot.

• Is there any way to control the video bitrate using FFmpeg Complex Filter other than -b:v ?

  8 février 2017, par srujith poondla

  I am trying to compress the video size by reducing the bitrate. I successfully achieved using -b:v in ffmpeg, its working perfectly. But that is not a filter so i am unable to chain the ffmpeg commands one after the other. Is there any other video filter in ffmpeg that controls the bitrate of the video so that i can chain the ffmpeg commands like mentioned in this link Filter Chaining FFmpeg