[FFmpeg-devel] [PATCH] rmdec.c: merge old/new packet reading code

[Kostya]

On Mon, Mar 09, 2009 at 09:42:59PM -0400, Ronald S. Bultje wrote:
> Hi again,
> 
> On Mon, Mar 9, 2009 at 6:37 PM, Ronald S. Bultje <rsbultje at gmail.com> wrote:
> > The move of the resync onto above the retrieve_cache() code isn't
> > strictly necessary (it could be below, directly after the "} else {"),
> > but is partly in preparation for the next patch which moves the cache
> > reading out of ff_rm_parse_packet() (which will return a positive
> > non-zero integer, and thus any non-zero return value in
> > ff_rm_parse_packet() will go back to resync => magic).
> 
> attached is a newer version that properly checks for EOF so that
> old_format actually stops at the end of a file.
> 
> Ronald

> Index: ffmpeg-svn/libavformat/rmdec.c
> ===================================================================
> --- ffmpeg-svn.orig/libavformat/rmdec.c	2009-03-09 18:02:40.000000000 -0400
> +++ ffmpeg-svn/libavformat/rmdec.c	2009-03-09 21:32:49.000000000 -0400
> @@ -691,57 +691,38 @@
>  static int rm_read_packet(AVFormatContext *s, AVPacket *pkt)
>  {
>      RMDemuxContext *rm = s->priv_data;
> -    ByteIOContext *pb = s->pb;
>      AVStream *st;
> -    int i, len;
> +    int i, len, seq = 1;
>      int64_t timestamp, pos;
>      int flags;
>  
> +resync:

do{

>      if (rm->audio_pkt_cnt) {
>          // If there are queued audio packet return them first
>          st = s->streams[rm->audio_stream_num];
>          ff_rm_retrieve_cache(s, s->pb, st, st->priv_data, pkt);
> -    } else if (rm->old_format) {
> -        RMStream *ast;
> +    } else {
> +        if (rm->old_format) {
> +            RMStream *ast;
>  
> -        st = s->streams[0];
> -        ast = st->priv_data;
> -        if (st->codec->codec_id == CODEC_ID_RA_288) {
> -            int x, y;
> -
> -            for (y = 0; y < ast->sub_packet_h; y++)
> -                for (x = 0; x < ast->sub_packet_h/2; x++)
> -                    if (get_buffer(pb, ast->pkt.data+x*2*ast->audio_framesize+y*ast->coded_framesize, ast->coded_framesize) <= 0)
> -                        return AVERROR(EIO);
> -            rm->audio_stream_num = 0;
> -            rm->audio_pkt_cnt = ast->sub_packet_h * ast->audio_framesize / st->codec->block_align - 1;
> -            // Release first audio packet
> -            av_new_packet(pkt, st->codec->block_align);
> -            memcpy(pkt->data, ast->pkt.data, st->codec->block_align); //FIXME avoid this
> -            pkt->flags |= PKT_FLAG_KEY; // Mark first packet as keyframe
> -            pkt->stream_index = 0;
> -        } else {
> -            /* just read raw bytes */
> -            len = RAW_PACKET_SIZE;
> -            len= av_get_packet(pb, pkt, len);
> -            pkt->stream_index = 0;
> -            if (len <= 0) {
> -                return AVERROR(EIO);
> -            }
> -            pkt->size = len;
> -        }
> -        rm_ac3_swap_bytes(st, pkt);
> +            st = s->streams[0];
> +            ast = st->priv_data;
> +            timestamp = AV_NOPTS_VALUE;
> +            len = ast->audio_framesize ?
> +                ast->coded_framesize * ast->sub_packet_h / 2 : RAW_PACKET_SIZE;
> +            flags = (seq == 1) ? 2 : 0;
>      } else {
> -        int seq=1;
> -resync:
>          len=sync(s, &timestamp, &flags, &i, &pos);
> -        if(len<0)
> -            return AVERROR(EIO);
>          st = s->streams[i];
> +        }
> +
> +        if(len<0 || url_feof(s->pb))
> +            return AVERROR(EIO);
>  
>          if (ff_rm_parse_packet (s, s->pb, st, st->priv_data, len, pkt,
>                                  &seq, &flags, &timestamp) < 0)
>              goto resync;
> +    }

} while(ff_rm_parse_packet (...) < 0);

I like goto's but this one is rather unneeded (and is not that qualified to
be called resync now).
  
>          if(  (st->discard >= AVDISCARD_NONKEY && !(flags&2))
>             || st->discard >= AVDISCARD_ALL){

And you can move discarding logic into the loop without need for emptying
cache inside it.

> @@ -755,7 +736,6 @@
>  
>          if((flags&2) && (seq&0x7F) == 1)
>              av_add_index_entry(st, pos, timestamp, 0, 0, AVINDEX_KEYFRAME);
> -    }
>  
>      return 0;
>  }