[FFmpeg-devel] [RFC] comment mpegvideo_split

[Michael Niedermayer]

On Wed, Mar 19, 2008 at 04:11:37PM +0100, Baptiste Coudurier wrote:
> Baptiste Coudurier wrote:
> > Michael Niedermayer wrote:
> >> On Tue, Mar 18, 2008 at 01:16:34AM +0100, Baptiste Coudurier wrote:
> >>> Hi,
> >>>
> >>> Currently, mpegvideo split function causes problems with containers
> >>> setting AVFMT_GLOBAL_HEADER, mov and mp4 in particular, because
> >>> MPEG-1/2 in those containers are to be muxed normally.
> >>>
> >>> I don't know any particular usage of the mpegvideo split function, so I
> >>> tend to want to comment it, to finally fix this issue.
> >>>
> >>> Anyone see another better alternative ?
> >> After a few more seconds :)
> >> The muxers could just dump extradata for the case of mpeg1/2 before keyframes,
> >> that should fix it i think. Its of course a little odd to first extract and
> >> then put it back in the muxer.
> >>
> > 
> > Would the attached patch be ok ?
> > 
> 
> This one is more correct, messy though.
> 
> -- 
> Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
> SMARTJOG SAS                                     http://www.smartjog.com
> Key fingerprint                 8D77134D20CC9220201FC5DB0AC9325C5C1ABAAA
> Phone: +33 1 49966312

> Index: libavformat/movenc.c
> ===================================================================
> --- libavformat/movenc.c	(revision 12503)
> +++ libavformat/movenc.c	(working copy)
> @@ -386,7 +386,8 @@
>          mov_write_esds_tag(pb, track);
>      else if(track->enc->codec_id == CODEC_ID_AMR_NB)
>          mov_write_amr_tag(pb, track);
> -    else if(track->vosLen > 0)
> +    else if(track->enc->codec_id != CODEC_ID_MPEG2VIDEO &&
> +            track->vosLen > 0)
>          mov_write_glbl_tag(pb, track);
>  
>      return updateSize (pb, pos);

I think this is unneeded ?


> @@ -1537,6 +1538,7 @@
>      AVCodecContext *enc = trk->enc;
>      unsigned int samplesInChunk = 0;
>      int size= pkt->size;
> +    int dump_extradata = 0;
>  
>      if (url_is_streamed(s->pb)) return 0; /* Can't handle that */
>      if (!size) return 0; /* Discard 0 sized packets */
> @@ -1582,6 +1584,10 @@
>          trk->vosLen = 640;
>          trk->vosData = av_malloc(trk->vosLen);
>          memcpy(trk->vosData, pkt->data, 640);
> +    } else if (enc->codec_id == CODEC_ID_MPEG2VIDEO && trk->vosLen > 4 &&
> +               AV_RB32(trk->vosData) == 0x000001b3 && pkt->flags & PKT_FLAG_KEY) {
> +        size += trk->vosLen;
> +        dump_extradata = 1;
>      }
>  
>      if (!(trk->entry % MOV_INDEX_CLUSTER_SIZE)) {
> @@ -1609,6 +1615,10 @@
>      trk->sampleCount += samplesInChunk;
>      mov->mdat_size += size;
>  
> +    if (dump_extradata) {
> +        put_buffer(pb, trk->vosData, trk->vosLen);
> +        size -= trk->vosLen;
> +    }
>      put_buffer(pb, pkt->data, size);
>  
>      put_flush_packet(pb);

ok, its not beautifull but i dont know a better solution. Maybe some
auto insertion of a bitstream filter, that could also be usefull to
simplify other cases ...
Anyway i think its better to commit this, we can always revert it if
someone does find a better solution.

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

Republics decline into democracies and democracies degenerate into
despotisms. -- Aristotle
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20080319/ae3cbd6d/attachment.pgp>