On Fri, Apr 04, 2008 at 01:45:44AM +0200, Michael Niedermayer wrote:
> On Thu, Apr 03, 2008 at 11:53:22PM +0200, Bartlomiej Wolowiec wrote:
> > On niedziela, 30 marca 2008, Michael Niedermayer wrote:
> > > Note, to add the header into the buffer calling ff_combine_frame() with
> > > END_NOT_FOUND and a smaller buffer size should work.
> > >
> > > After its in the buffer you just run the header decoder thing over the
> > > header and when you know the final frame size you call ff_combine_frame
> > > with appropriate next value.
> > >
> > > Anyway iam not insisting on you changing the current aac/ac3 parser to use
> > > ff_combine_frame()
> > > But what you will end up implementing will be quite similar in
> > > functionality to ff_combine_frame()
> > >
> > > [...]
> >
> > Hmm...
> > I tried to implement it using ff_combine_frame, but the code which I got
> > is
> > in my opinion significantly worse. Main problems which I had:
> > -ff_combine_frame is rather adapted to using on one frame, when in buffer
> > is
> > one frame and it currently reads the next one it isn't convenient (the
> > whole
> > buffer size is not just a new frame's size, so that we should remember size
> > of earlier frames).
> > -in the genuine code there is
> > memmove(s->frame_start, s->frame_start + 1, s->header_size - 1);
> > s->frame_ptr--;
> > here we can operate on pc->buffer and pc->index (remembering also where the
> > new frame begins). However, surely it isn't the simpliest solution...
>
> What i had in mind is below, this is blindly written and likely contains bugs.
> I did spot one each time i looked at it :)
> But it does not look fundamentally worse to me, it also has the advantage that
> its not full of unneeded memcpys and memmoves.
>
> while(s->remaining_size <= buf_size){
> if(s->remaining_size && !s->need_next_header){
> i= s->remaining_size;
> s->remaining_size= 0;
> goto output_frame;
> }else{ //we need a header first
> for(i=s->remaining_size; i<buf_size; i++){
> ctx->state= (ctx->state<<8) + buf[i];
> if((len=parse_header(ctx->state, &s->need_next_header,
> &s->new_frame_start)))just to clarify before you ask ... state is a 64bit variable in your context unrelated to the 32bit state ff_combine_frame() plays with. [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Democracy is the form of government in which you can choose your dictator
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