[FFmpeg-devel] [PATCH] avformat/rtsp: fix infinite loop with udp transport

[Andriy Gelman]

Hi Zhao,

On Tue, 25. Aug 01:17, Zhao Zhili wrote:
> Ping again.
> 
> > On Aug 17, 2020, at 8:05 AM, zhilizhao <quinkblack at foxmail.com> wrote:
> > 
> > Please help review the patch, thanks!
> > 
> >> On Aug 6, 2020, at 4:50 PM, quinkblack at foxmail.com wrote:
> >> 
> >> From: Zhao Zhili <quinkblack at foxmail.com>
> >> 
> >> User report: http://ffmpeg.org/pipermail/ffmpeg-user/2020-August/049494.html
> >> 
> >> server:
> >> ./ffmpeg -i test.mp4 -c copy -f rtsp -rtsp_transport udp  rtsp://localhost:12345/live.sdp
> >> 
> >> client:
> >> ./ffmpeg_g -y -rtsp_flags listen -timeout 100 -i rtsp://localhost:12345/live.sdp -c copy test.mp4
> >> ---
> >> libavformat/rtsp.c | 5 +++++
> >> 1 file changed, 5 insertions(+)
> >> 
> >> diff --git a/libavformat/rtsp.c b/libavformat/rtsp.c
> >> index 5d8491b74b..0fb9fde6b4 100644
> >> --- a/libavformat/rtsp.c
> >> +++ b/libavformat/rtsp.c
> >> @@ -2051,6 +2051,11 @@ static int udp_read_packet(AVFormatContext *s, RTSPStream **prtsp_st,
> >>                if ((ret = parse_rtsp_message(s)) < 0) {
> >>                    return ret;
> >>                }
> >> +                /* Since there is no way to detect eof of udp streams, break
> >> +                 * the loop in teardown state to prevent run into infinite.
> >> +                 */
> >> +                if (rt->state == RTSP_STATE_IDLE)
> >> +                    return AVERROR_EOF;
> >>            }
> >> #endif
> >>        } else if (n == 0 && ++timeout_cnt >= MAX_TIMEOUTS) {

Currently when the stream finishes a BYE message is not sent from the server.  

You can ensure that the message is sent by adding the send_bye option with the
flag:
"-rtpflags send_bye"

This will also fix the problem.

What I think is more confusing is that "-rtp_flags send_bye" is also valid on
the command line but will have no effect..

-- 
Andriy