[Ffmpeg-devel] BUG - buffer overflow

[Wolfram Gloger]

Hi,

[mpeg -> mpeg transcoding]

> After running for a long time (2G original file) at about the 50% mark I
> get a ton of these errors:
> 
> [dvd @ 0x82adfc0]buffer underflow

I am sure there is a bug in the mpeg muxer but I don't know whether it
is the same problem you are seeing.  Please try the patch below.  I
noticed this problem only with subtitle substreams with a very low
packets/second rate.

Regards,
Wolfram.

diff -ur ffmpeg/libavformat/mpeg.c ffmpeg-wg/libavformat/mpeg.c
--- ffmpeg/libavformat/mpeg.c	Fri Sep 23 19:54:33 2005
+++ ffmpeg-wg/libavformat/mpeg.c	Tue Oct 18 10:47:48 2005
@@ -30,7 +30,7 @@
     int64_t dts;
     int size;
     int unwritten_size;
-    int flags;
+  //int flags;
     struct PacketDesc *next;
 } PacketDesc;
 
@@ -1181,7 +1190,8 @@
     AVStream *st = ctx->streams[stream_index];
     StreamInfo *stream = st->priv_data;
     int64_t pts, dts;
-    PacketDesc *pkt_desc;
+    PacketDesc *pkt_desc, *dec_next;
+    int requeue = 0;
     const int preload= av_rescale(ctx->preload, 90000, AV_TIME_BASE);
     const int is_iframe = st->codec->codec_type == CODEC_TYPE_VIDEO && (pkt->flags & PKT_FLAG_KEY);
     
@@ -1191,18 +1201,26 @@
     if(pts != AV_NOPTS_VALUE) pts += preload;
     if(dts != AV_NOPTS_VALUE) dts += preload;
 
-//av_log(ctx, AV_LOG_DEBUG, "dts:%f pts:%f flags:%d stream:%d nopts:%d\n", dts/90000.0, pts/90000.0, pkt->flags, pkt->stream_index, pts != AV_NOPTS_VALUE);
-    if (!stream->premux_packet)
+//av_log(ctx, AV_LOG_DEBUG, "dts:%f pts:%f flags:%d i=%d size:%d premux=%p\n", dts/90000.0, pts/90000.0, pkt->flags, pkt->stream_index, size, stream->premux_packet);
+    if (!stream->premux_packet) {
         stream->next_packet = &stream->premux_packet;
+        requeue= 1;
+    }
     *stream->next_packet=
-    pkt_desc= av_mallocz(sizeof(PacketDesc));
+    pkt_desc= av_malloc(sizeof(PacketDesc));
     pkt_desc->pts= pts;
     pkt_desc->dts= dts;
     pkt_desc->unwritten_size=
     pkt_desc->size= size;
+    pkt_desc->next= NULL;
     if(!stream->predecode_packet)
         stream->predecode_packet= pkt_desc;
+    else if (requeue) {
+        for (dec_next= stream->predecode_packet; dec_next->next; dec_next= dec_next->next);
+        dec_next->next = pkt_desc;
+    }
+        
     stream->next_packet= &pkt_desc->next;
 
     fifo_realloc(&stream->fifo, fifo_size(&stream->fifo, NULL) + size + 1);