[Ffmpeg-devel] [FWD] [PATCH] immediate decoding of dvd stills

[Michael Niedermayer]

Hi

On Wed, Nov 29, 2006 at 01:01:58AM +0100, Nico Sabbi wrote:
> Michael Niedermayer wrote:
> 
> >is there a problem with return buf_size; ?
> 
> no, but why returning ret < bytes actually consumed? I find 
> it misleadig

hmm, i didnt suggest return 0, but i see the problem now, i assumed that
there would always be 1 frame per packet and the end code also alone in one
that of course isnt guranteed even though it should always be the case with
an AVParser


[...]

> Index: libavcodec/mpeg12.c
> ===================================================================
> --- libavcodec/mpeg12.c	(revisione 7167)
> +++ libavcodec/mpeg12.c	(copia locale)
> @@ -3037,6 +3037,12 @@
>                  }
>              }
>          }
> +    }else{
> +        /* look for SEQ_END_CODE at the last data in this buffer*/
> +        /* dvd's won't send the next frame start on still images*/
> +        /* SEQ_END_CODE will have to stay at the beginning of a frame*/
> +        if(state == SEQ_END_CODE)
> +            return i-3;
>      }
>      pc->state= state;
>      return END_NOT_FOUND;
> @@ -3054,11 +3060,12 @@
>      int ret, input_size;
>      AVFrame *picture = data;
>      MpegEncContext *s2 = &s->mpeg_enc_ctx;
> +    int endsequence = !memcmp(buf, (char[]){0,0,1,0xB7}, 4);
>      dprintf("fill_buffer\n");

buf can be NULL if buf_size==0


>  
> -    if (buf_size == 0) {
> +    if (buf_size == 0 || endsequence) {
>          /* special case for last picture */
> -        if (s2->low_delay==0 && s2->next_picture_ptr) {
> +        if (s2->low_delay==0 && !endsequence && s2->next_picture_ptr) {
>              *picture= *(AVFrame*)s2->next_picture_ptr;
>              s2->next_picture_ptr= NULL;

this is wrong, if you output a picture, then it must be removed otherwise
it would be output again with the next I frame

and no iam not saying s2->next_picture_ptr= NULL is enough for this, just
that doing nothing is definitly not correct

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In the past you could go to a library and read, borrow or copy any book
Today you'd get arrested for mere telling someone where the library is