[Libav-user] avio read proxy

[Pavel Sokolov]

Problem was solved with adding AVSEEK_SIZE to seek proxy function:

    int64_t FFmpegIoProxy::seekFunction(int64_t offset, int whence){
      if (offset == 0 && whence == AVSEEK_SIZE)
         return avio_size(_origAvio);

      return avio_seek(_origAvio, offset, whence);
    }



07.02.2013 18:00, Pavel Sokolov пишет:
> Hi!
>
> For some reasons I need to implement universal avio proxy, which will 
> support all ffmpeg protocols.
> The main goal is to parse all avio_read traffic via some custom function.
>
> So, I create custom context with direct i/o:
>
> AVIOContext* _ffmpeg_io_context = avio_alloc_context(NULL, 0,
> 0, // writeflag
> this, //context (opaque)
> readFunctionWrapper, //read
> NULL , //write
> seekFunctionWrapper );//seek
> _ffmpeg_io_context->direct = true;
>
> After I open the original avio:
>
> AVIOContext* _origAvio = NULL;
> avio_open2(&_origAvio, _url.c_str(), AVIO_FLAG_READ, NULL, NULL);
> _ffmpeg_io_context->seekable = _origAvio->seekable; /// Set to custom 
> avio seekable flags from the original avio
>
> My custom functions looks like this:
>
> int FFmpegIoProxy::readFunction(uint8_t* buf, int buf_size){
> int res = avio_read(_origAvio, buf, buf_size);
> if (res>0){
> ... do something with buf
> }
> return buf;
> }
>
> int64_t FFmpegIoProxy::seekFunction(int64_t offset, int whence){
> return avio_seek(_origAvio, offset, whence);
> }
>
> After I open avformat with custom i/o:
>
> _ffmpeg_format_context = avformat_alloc_context();
> _ffmpeg_format_context->pb= _ffmpeg_io_context;
> avformat_open_input(&_ffmpeg_format_context, NULL, NULL, NULL);
>
>
> Local (file://) url works fine, but when I try to open http:// 
> protocol I see messages:
>
> [http @ 0x4b97c0] HTTP error 416 Requested Range Not Satisfiable
>
> So, really it requesting out-of range data.
>
> Is somebody knows, what is wrong? May be I need to set some more 
> fields of my proxy avio?
>

-- 

With best regards, Pavel A. Sokolov
mobile: +7(921)419-1819
skype: pavel_a_sokolov