[FFmpeg-devel] [PATCH] SIFF demuxer and decoder

[Michael Niedermayer]

On Tue, Oct 16, 2007 at 07:19:10AM +0300, Kostya wrote:
[...]
>  
> > [...]
> > > +            if(c->has_audio){
> > > +                c->blkdata = av_realloc(c->blkdata, size);
> > > +                memcpy(c->blkdata, pkt->data, pkt->size);
> > > +            }
> > > +            flags = pkt->data[0];
> > > +            c->next_audio = !!(flags & VB_HAS_AUDIO);
> > > +        }else{
> > > +            //parse block
> > > +            flags = c->blkdata[0];
> > > +            snddata = c->blkdata + 2 + ((flags & VB_HAS_GMC) ? 4 : 0);
> > > +            size = AV_RL32(snddata) - 4;
> > > +            if (av_new_packet(pkt, size) < 0)
> > > +                return AVERROR(ENOMEM);
> > > +            memcpy(pkt->data, snddata + 4, size);
> > > +        }
> > 
> > this looks wrong, it passes the audio to the video decoder
> > it also does a lot of unneeded memcpy()
> > please clean this up
> > video -> video stream
> > audio -> audio stream
> > and no memcpy
> 
> It's a bit problematic.
> Frame structure:
>  whole frame size
>  flags
>  if(flags & gmc)
>   motion vector
>  if(flags & audio)
>   audio data
>  if(flags & video)
>   video data
>  if(flags & palette)
>   palette data
> 
> Can you suggest a way to do demuxing?

something like:

frame_size= get()
flags= get()
if(flags & gmc)
    mv=get();
if(flags & audio){
    aud_pkt= get_packet()
}
if(flags & (video|palette)){
    vid_pkt= alloc_packet(vid_size + pal_size + gmc + 1)
    vid_pkt->data[0]= flags;
    vid_pkt->data[1]= mv
    if(flags & video)
        read(vid_pkt->data+2, vid_size)
    if(flags & palette)
        read(vid_pkt->data+2+vid_size, pal_size)
}

if(vid_pkt){
    t= vid_pkt; vid_pkt=0
    return t;
}

if(aud_pkt){
    t= aud_pkt; aud_pkt=0
    return t;
}


[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The greatest way to live with honor in this world is to be what we pretend
to be. -- Socrates
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