[SCM] libav/experimental: Fix index generation in the way that it was supposed to be used. See the discussion in the ML thread "[PATCH] rmdec.c: merge old/new packet reading code".

[siretart at users.alioth.debian.org]

The following commit has been merged in the experimental branch:
commit 7a160bca8334d55a51e7256be8b6ae61302374b9
Author: Ronald S. Bultje <rsbultje at gmail.com>
Date:   Sun Mar 15 20:14:25 2009 +0000

    Fix index generation in the way that it was supposed to be used. See the
    discussion in the ML thread "[PATCH] rmdec.c: merge old/new packet reading
    code".
    
    Over time, this code broke somewhat, e.g. seq was never actually written
    into (and was thus always 1, therefore the seq condition was always true),
    whereas it was supposed to be set to the sequence number of the video slice
    in case the video frame is divided over multiple RM packets (slices). The
    problem of this is that packets other than those containing the beginning
    of a video frame would be indexed as well.
    Secondly, flags&2 is supposed to be true for video keyframes and for these
    audio packets containing the start of a block. For some codecs (e.g. AAC),
    that is every single packet, whereas for others (e.g. cook), that is the
    packet containing the first of a series of scrambled packets that are to be
    descrambled together. Indexing any of the following would lead to incomplete
    and thus useless frames. Problem here is that flags would be reset to 2 to
    indicate that the first packet is ready to be returned, and in addition if
    no data was left to be returned (which is always true for the first packet),
    then we wouldn't actually write the index entry anyway.
    All in all, the idea was good and it probably worked at some point, but that
    is long ago. This patch should at the very least make it likely for this code
    to be executed again at the right times, i.e. the way it was originally
    intended to be used.
    
    Originally committed as revision 17993 to svn://svn.ffmpeg.org/ffmpeg/trunk

diff --git a/libavformat/rmdec.c b/libavformat/rmdec.c
index a017418..3af429e 100644
--- a/libavformat/rmdec.c
+++ b/libavformat/rmdec.c
@@ -492,7 +492,7 @@ skip:
 
 static int rm_assemble_video_frame(AVFormatContext *s, ByteIOContext *pb,
                                    RMDemuxContext *rm, RMStream *vst,
-                                   AVPacket *pkt, int len)
+                                   AVPacket *pkt, int len, int *pseq)
 {
     int hdr, seq, pic_num, len2, pos;
     int type;
@@ -527,6 +527,7 @@ static int rm_assemble_video_frame(AVFormatContext *s, ByteIOContext *pb,
     }
     //now we have to deal with single slice
 
+    *pseq = seq;
     if((seq & 0x7F) == 1 || vst->curpic_num != pic_num){
         vst->slices = ((hdr & 0x3F) << 1) + 1;
         vst->videobufsize = len2 + 8*vst->slices + 1;
@@ -593,7 +594,7 @@ ff_rm_parse_packet (AVFormatContext *s, ByteIOContext *pb,
 
     if (st->codec->codec_type == CODEC_TYPE_VIDEO) {
         rm->current_stream= st->id;
-        if(rm_assemble_video_frame(s, pb, rm, ast, pkt, len))
+        if(rm_assemble_video_frame(s, pb, rm, ast, pkt, len, seq))
             return -1; //got partial frame
     } else if (st->codec->codec_type == CODEC_TYPE_AUDIO) {
         if ((st->codec->codec_id == CODEC_ID_RA_288) ||
@@ -705,9 +706,9 @@ 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, res;
     int64_t timestamp, pos;
-    int flags;
+    int old_flags, flags;
 
     if (rm->audio_pkt_cnt) {
         // If there are queued audio packet return them first
@@ -751,8 +752,12 @@ resync:
             return AVERROR(EIO);
         st = s->streams[i];
 
-        if (ff_rm_parse_packet (s, s->pb, st, st->priv_data, len, pkt,
-                                &seq, &flags, &timestamp) < 0)
+        old_flags = flags;
+        res = ff_rm_parse_packet (s, s->pb, st, st->priv_data, len, pkt,
+                                  &seq, &flags, &timestamp);
+        if((old_flags&2) && (seq&0x7F) == 1)
+            av_add_index_entry(st, pos, timestamp, 0, 0, AVINDEX_KEYFRAME);
+        if (res < 0)
             goto resync;
 
         if(  (st->discard >= AVDISCARD_NONKEY && !(flags&2))
@@ -764,9 +769,6 @@ resync:
             }
             goto resync;
         }
-
-        if((flags&2) && (seq&0x7F) == 1)
-            av_add_index_entry(st, pos, timestamp, 0, 0, AVINDEX_KEYFRAME);
     }
 
     return 0;

-- 
Libav/FFmpeg packaging