[FFmpeg-trac] #10578(avformat:new): send RTSP keep alive even when paused

[FFmpeg]

#10578: send RTSP keep alive even when paused
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             Reporter:  tmc2001   |                     Type:  defect
               Status:  new       |                 Priority:  normal
            Component:  avformat  |                  Version:  unspecified
             Keywords:            |               Blocked By:
             Blocking:            |  Reproduced by developer:  0
Analyzed by developer:  0         |
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 Workflow:
 1. Have a RTSP server that supports Pause.
 2. Have ffmpeg play a video from that server (rtsp://<ipaddr>:...).
 3. Pause the video in ffmpeg (call av_read_pause)
 4. ffmpeg does NOT properly send the keep alive when Paused
 (either "GET_PARAMETER" or "OPTIONS"). This is the bug.
 5. Since the RTSP server expects the keep alive, after the specified
 timeout (usually 60s) it closes the connection.


 The bug is in:
 File: libavformat/rtspdec.c
 Method: rtsp_read_packet

 This method first does ff_rtsp_fetch_packet, which fails when the server
 is Paused, causing it to never send the "GET_PARAMETER" or "OPTIONS" which
 is placed immediately after this call.


 Potential easy fix:
 Simply move that block of code before ff_rtsp_fetch_packet.

 That is, move the entire if block:
 if (!(rt->rtsp_flags & RTSP_FLAG_LISTEN)) { ... }

 just before the call to:
 ret = ff_rtsp_fetch_packet(s, pkt);


 I have tested this and it seems to work well for our cases.
 Sent this to ffmpeg-devel mailing list as well:
 http://ffmpeg.org/pipermail/ffmpeg-devel/2023-August/313608.html


 Would appreciate if an experienced DEV would approve and integrate into
 ffmpeg.
 Thank you.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10578>
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