some sanity checks on what is muxed, invalid timestamps in mpeg are very...

some sanity checks on what is muxed, invalid timestamps in mpeg are very common and lead to strange errors in the mpeg muxer otherwise

Originally committed as revision 3752 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/utils.c

@@ -2034,7 +2034,7 @@ int av_write_header(AVFormatContext *s)
 }
 
 //FIXME merge with compute_pkt_fields
-static void compute_pkt_fields2(AVStream *st, AVPacket *pkt){
+static int compute_pkt_fields2(AVStream *st, AVPacket *pkt){
     int b_frames = FFMAX(st->codec.has_b_frames, st->codec.max_b_frames);
     int num, den, frame_size;
 
@@ -2079,6 +2079,15 @@ static void compute_pkt_fields2(AVStream *st, AVPacket *pkt){
             pkt->dts= pkt->pts;
     }
     
+    if(st->cur_dts && st->cur_dts != AV_NOPTS_VALUE && st->cur_dts >= pkt->dts){
+        av_log(NULL, AV_LOG_ERROR, "error, non monotone timestamps %Ld >= %Ld\n", st->cur_dts, pkt->dts);
+        return -1;
+    }
+    if(pkt->dts != AV_NOPTS_VALUE && pkt->pts != AV_NOPTS_VALUE && pkt->pts < pkt->dts){
+        av_log(NULL, AV_LOG_ERROR, "error, pts < dts\n");
+        return -1;
+    }
+
 //    av_log(NULL, AV_LOG_DEBUG, "av_write_frame: pts2:%lld dts2:%lld\n", pkt->pts, pkt->dts);
     st->cur_dts= pkt->dts;
     st->pts.val= pkt->dts;
@@ -2100,6 +2109,7 @@ static void compute_pkt_fields2(AVStream *st, AVPacket *pkt){
     default:
         break;
     }
+    return 0;
 }
 
 static void truncate_ts(AVStream *st, AVPacket *pkt){
@@ -2124,7 +2134,9 @@ int av_write_frame(AVFormatContext *s, AVPacket *pkt)
 {
     int ret;
 
-    compute_pkt_fields2(s->streams[pkt->stream_index], pkt);
+    ret=compute_pkt_fields2(s->streams[pkt->stream_index], pkt);
+    if(ret<0)
+        return ret;
     
     truncate_ts(s->streams[pkt->stream_index], pkt);
 
@@ -2219,7 +2231,8 @@ static int av_interleave_packet(AVFormatContext *s, AVPacket *out, AVPacket *in,
 int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt){
     AVStream *st= s->streams[ pkt->stream_index];
 
-    compute_pkt_fields2(st, pkt);
+    if(compute_pkt_fields2(st, pkt) < 0)
+        return -1;
     
     //FIXME/XXX/HACK drop zero sized packets
     if(st->codec.codec_type == CODEC_TYPE_AUDIO && pkt->size==0)