[Ffmpeg-devel] [PATCH] Add Dirac support to ffmpeg]

[Andrew Kennedy]

Hi,

I've altered the code in line with your recommendations. However, I'm still 
not entirely clear about the following:

>and if i understand the demuxing code in drc.c correctly, then it does only
>split the stream into packets, this should be done in a AVParser instead for
>raw "containers", and the remaining (de)muxing code might fit better in
>libavformat/raw.c instead of a separate file, but a separate file is fine too
>if preferred

So, if I understand this correctly, the parsing code in drc.c is shifted to 
parser.c (or a suitable place to use a Dirac parser). This then receives 
data from the 'raw' file read in raw.c. Is this correct? I thought 
av_read_frame() should read an entire frame of data, so I'm not clear how 
this is now possible. Are you saying that I should use the boolean in 
avcodec_decode_video() because the frame boundaries will now be split 
across packets? Please can you elaborate.

Thanks in advance
Andrew




>Hi
>
>On Thursday 07 July 2005 14:38, Anuradha Suraparaju wrote:
> > **Dirac patch for ffmpeg
> > **Tested with ffmpeg cvs (as of July 7, 2007 10:00am) and
> >   FFMpeg-20050707
> > **Author(s): Andrew Kennedy (dirac_dev at users.sourceforge.net) (main)
> >              Anuradha Suraparaju (asuraparaju at users.sourceforge.net)
> >              (minor mods)
> >
> > Dirac is an open-source video codec currently under development. Both
> > the encoder and decoder have been integrated with ffmpeg. This patch is
> > only a basic integration such that only the salient paremeters are
> > currently passed from ffmpeg to Dirac. As Dirac develops, especially
> > with the integration of  a formalised bit-stream syntax,  then more
> > complex screnarios can be dealt with. Encoded Dirac files, with the
> > right patch, can be played back using MPlayer.
>[...]
>
> > +dirac_encoder_presets_t GetDiracPreset(AVCodecContext *avccontext)
>
>shouldnt that and a few other functions be static to avoid namespace
>pollution, or are they used outside dirac.c?
>
>
> > +       default:
> > +               av_log (avccontext, AV_LOG_ERROR, "this codec supports 
> only
>YUV420P\n");
> > +               return format420;
> > +
> > +       }
> > +
> > +       return format420;
>
>the last return is unreachable, IMHO it should be removed
>
>
>it seems GetFrameBufferSize() could be replaced by avpicture_get_size()
>
>
> > +static unsigned char* dirac_videobuffer = 0;
> > +static int dirac_videobuf_len =0;
> > +static unsigned char dirac_videobuf_code[5];
> > +static int dirac_videobuf_code_len = 0;
>
>non constant static/globals arent acceptable, it should be possible to use
>several demuxers or decoders at once
>
>
> > +         }
> > +
> > +           dirac_videobuffer[dirac_videobuf_len++] = byte;
>
>i dont care what indention style is used as long as its not the randomized one
>
>
> > +    av_free(dirac_videobuffer);
> > +    dirac_videobuffer=0;
>
>this could be replaced by av_freep()
>
>
>and if i understand the demuxing code in drc.c correctly, then it does only
>split the stream into packets, this should be done in a AVParser instead for
>raw "containers", and the remaining (de)muxing code might fit better in
>libavformat/raw.c instead of a separate file, but a separate file is fine too
>if preferred
>
>--
>Michael
>
>_______________________________________________
>ffmpeg-devel mailing list
>ffmpeg-devel at mplayerhq.hu
>http://mplayerhq.hu/mailman/listinfo/ffmpeg-devel