Workaround buggy flv files (#2590).

 It seems that (a lot of?) flv files does not correctly set PTS,
so ignore them, with luck the decoder (avcodec) will recreate
them.
 It might break some valid files, so report any regression.

(It needs the AVCodecContext::ticks_per_frame change).

modules/demux/avformat/demux.c

@@ -438,6 +438,8 @@ static int Demux( demux_t *p_demux )
         av_free_packet( &pkt );
         return 1;
     }
+    const AVStream *p_stream = p_sys->ic->streams[pkt.stream_index];
+
     if( ( p_frame = block_New( p_demux, pkt.size ) ) == NULL )
     {
         return 0;
@@ -453,17 +455,24 @@ static int Demux( demux_t *p_demux )
 
     p_frame->i_dts = ( pkt.dts == (int64_t)AV_NOPTS_VALUE ) ?
         0 : (pkt.dts) * 1000000 *
-        p_sys->ic->streams[pkt.stream_index]->time_base.num /
-        p_sys->ic->streams[pkt.stream_index]->time_base.den - i_start_time;
+        p_stream->time_base.num /
+        p_stream->time_base.den - i_start_time;
     p_frame->i_pts = ( pkt.pts == (int64_t)AV_NOPTS_VALUE ) ?
         0 : (pkt.pts) * 1000000 *
-        p_sys->ic->streams[pkt.stream_index]->time_base.num /
-        p_sys->ic->streams[pkt.stream_index]->time_base.den - i_start_time;
+        p_stream->time_base.num /
+        p_stream->time_base.den - i_start_time;
     if( pkt.duration > 0 )
         p_frame->i_length = pkt.duration * 1000000 *
-            p_sys->ic->streams[pkt.stream_index]->time_base.num /
-            p_sys->ic->streams[pkt.stream_index]->time_base.den - i_start_time;
+            p_stream->time_base.num /
+            p_stream->time_base.den - i_start_time;
 
+    if( pkt.dts != AV_NOPTS_VALUE && pkt.dts == pkt.pts &&
+        p_stream->codec->codec_type == CODEC_TYPE_VIDEO )
+    {
+        /* Add here notoriously bugged file formats/samples regarding PTS */
+        if( !strcmp( p_sys->fmt->name, "flv" ) )
+            p_frame->i_pts = 0;
+    }
 #ifdef AVFORMAT_DEBUG
     msg_Dbg( p_demux, "tk[%d] dts=%"PRId64" pts=%"PRId64,
              pkt.stream_index, p_frame->i_dts, p_frame->i_pts );