rtpdec: fix issue with conversion from unsigned to signed

When receiving an RTCP packet, the difference between the last RTCP
timestamp and the base timestamp may be negative. As these timestamps
are of the uint32_t type, the result becomes a large integer. Cast
the difference to int32_t to avoid this issue.

The result of this issue is very large start times for RTSP
streams, and difficulty to restart correctly after a pause.

Signed-off-by: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
Signed-off-by: Martin Storsjö <martin@martin.st>

diff --git a/libavformat/rtpdec.c b/libavformat/rtpdec.c
index 97f142815ace35dc0ec2dc948914a1f0fee77b35..522d951d357cfe4332a872b34dba3e6dc06f9842 100644 (file)
--- a/libavformat/rtpdec.c
+++ b/libavformat/rtpdec.c
@@ -143,7 +143,7 @@ static int rtcp_parse_packet(RTPDemuxContext *s, const unsigned char *buf,
                 s->first_rtcp_ntp_time = s->last_rtcp_ntp_time;
                 if (!s->base_timestamp)
                     s->base_timestamp = s->last_rtcp_timestamp;
-                s->rtcp_ts_offset = s->last_rtcp_timestamp - s->base_timestamp;
+                s->rtcp_ts_offset = (int32_t)(s->last_rtcp_timestamp - s->base_timestamp);
             }
 
             break;