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List:       xine-devel
Subject:    Re: [xine-devel] Re: [xine-cvs] CVS: xine-lib/src/liba52 xine_decoder.c,1.61,1.62
From:       James Courtier-Dutton <James () superbug ! demon ! co ! uk>
Date:       2003-11-17 21:23:25
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Michael Roitzsch wrote:
> Hi James,
> 
> 
>>If you think about this more, you will see that one can use either
>>variable. I just choose the first one. decoder_info[1]
>>If info[1]=1, PTS =  PTS for the a52 frame that starts in this fifo
>>block. (aka.this a52 frame)
>>If info[2]=2, PTS = PTS for this a52 frame, and PTS=0 for next a52
>>frame.
> 
> 
> Ok, so I think the correct code in liba52 to fill PTS list would be 
> something like this:
> 
> Replace this:
> 
>   /* FIXME: the code here does not match the explanation above */
>   if (buf->pts) {
>     int32_t info;
>     info = buf->decoder_info[1];
>     this->pts = buf->pts;
>     this->pts_list[this->pts_list_position]=buf->pts;
>     this->pts_list_position++;
>     if( this->pts_list_position > 3 )
>       this->pts_list_position = 3;
>     if (info == 2) {
>       this->pts_list[this->pts_list_position]=0;
>       this->pts_list_position++;
>       if( this->pts_list_position > 3 )
>         this->pts_list_position = 3;
>     }
>   }
> 
> with this:
> 
>   pts = buf->pts;
>   for (i = buf->decoder_info[1]; i > 0; i--) {
>     if (this->pts_list_position < 5)
>       this->pts_list[this->pts_list_position++] = pts;
>     else
>       XINE_ASSERT(0, "PTS fifo overflow");
>     pts = 0;
>   }
> 
> Does this look correct?

Hum? Both versions of code do the same thing, so what exactly is the 
reason to change it? Or have I missed something, and your code it doing 
something differently?

> 
> 
>>I have been thinking about the possiblility of moving liba52 sync
>>code into the demuxer. Just forcing the demuxer to always output
>>complete A52 frames and deal with the PTS value in the demuxer
>>instead.
> 
> 
> You know that there are 6 demuxer capable of outputting A52 and this 
> number could still grow. That would be a lot of redundant code. I think 
> this should be encapsulated on the decoder side. Decoders should never 
> assume a certain buffer fragmentation they like.
> 
> Michael
> 

Ok, I will only put it in demux_ts.c then.



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