Recherche avancée

Sur d’autres sites (7199)

• lavf/davs2 : Do not mix declarations and code.

  14 septembre 2018, par Carl Eugen Hoyos

  lavf/davs2 : Do not mix declarations and code.
  Fixes the following warning :
  
  libavformat/davs2.c:39:5 : warning : ISO C90 forbids mixed declarations and code
  

  • [DH] libavformat/davs2.c

• avcodec/mobiclip : Rewrite code to make it clearer

  18 novembre 2021, par Andreas Rheinhardt

  avcodec/mobiclip : Rewrite code to make it clearer
  In order to know that the earlier code did not use uninitialized
  
  values one needs to know that the lowest four bits of each used
  
  value of pframe_block4x4_coefficients_tab do not vanish identically.
  
  E.g. Coverity did not get this and warned about it in ticket #1466632.
  
  Fix this by slightly rewriting the code.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/mobiclip.c

• How to embed additional metadata to a video file in libavcodec (FFmpeg C source code fork)

  7 mars 2023, par leavittx

  I'm extending an existing codec (Hap) inside ffmpeg library, adding some additional stuff to it (modifying FFmpeg code in my own fork of it)

  


  One of the things I'd like to do is to store a per-file maximum encoded packet size in some global header/metadata so I can use it later while doing decoding (generally, the metadata/info to store can be arbitrary, size is just what I currently need for some specialized decoder I'm writing).

  


  I'm modifying the ffmpeg code file
https://github.com/FFmpeg/FFmpeg/blob/master/libavcodec/hapenc.c

  


  EDIT : What I'd like to achieve

  


  

  • Compute some numeric value during the encoding (namely, the maximum encoded frame size for the video - it's needed for a specialized fast decoder to not read all the frames beforehand) - that is done already

  


  • Store that value in the video file metadata (looks like it should be done on container level)

  


  


  My initial incorrect attempt :
But I don't currently see any possibility to save any info outside of a single packet being produced by hap_encode function and written to AVPacket *pkt parameter.

  


  

  1. Set dict parameter on AVCodecContext *avctx's priv_data :

  


  


      av_opt_set_int(avctx->priv_data, "max_compressed_frame_size", <size>, 0);&#xA;    av_opt_set(avctx->priv_data, "max_compressed_frame_size", "", 0);&#xA;</size>

  


  Later, while decoding av_opt_get/av_opt_get_int report non-existing key.

  


  

  2. Set various AVCodecContext *avctx fields :

  


  


      avctx->flags2 = <size>;&#xA;    avctx->extradata_size = <size>;&#xA;    avctx->ticks_per_frame = <size>;&#xA;    avctx->delay = <size>;&#xA;</size></size></size></size>

  


  They all also seem to be not preserved when doing decoding later (I get just default values from decoder's AVCodecContext)