[FFmpeg-devel] make work (live) libsrt

[Tudor Suciu]

Hello,

Is this patch in a better shape for inclusion?

Regards,

On Fri, Aug 24, 2018 at 2:46 AM mypopy at gmail.com <mypopy at gmail.com> wrote:

> On Fri, Aug 24, 2018 at 2:55 AM Marton Balint <cus at passwd.hu> wrote:
> >
> >
> >
> > On Thu, 23 Aug 2018, mypopy at gmail.com wrote:
> >
> > > On Wed, Aug 22, 2018 at 4:30 AM Tudor Suciu <tudor.suciu at gmail.com>
> wrote:
> > >>
> > >> Hello,
> > >>
> > >> I get errors when I try to send a live srt stream that the first
> packet is
> > >> too big:
> > >> 21:30:39.896626/ffmpeg*E: SRT.c: LiveSmoother: payload size: 1504
> exceeds
> > >> maximum allowed 1316
> > >>
> > >> Here are example commands for server and client:
> > >> ffmpeg -re -i ~/Downloads/ToS-4k-1920.mov -vcodec libx264 -g 50 -refs
> 1 -s
> > >> 640x360 -b:v 1000k -acodec aac -b:a 64k -flush_packets 0 -f mpegts
> "srt://
> > >> 127.0.0.1:5555?mode=listener"
> > >> ffplay srt://127.0.0.1:5555
> > >>
> > >> A patch that fully solves the issue is:
> > >> diff --git a/libavformat/libsrt.c b/libavformat/libsrt.c
> > >> index 0f9529d263..156a4776e2 100644
> > >> --- a/libavformat/libsrt.c
> > >> +++ b/libavformat/libsrt.c
> > >> @@ -412,6 +412,8 @@ static int libsrt_open(URLContext *h, const char
> *uri,
> > >> int flags)
> > >>          return AVERROR_UNKNOWN;
> > >>      }
> > >>
> > >> +    h->max_packet_size = 1316;
> > >> +
> > >>      /* SRT options (srt/srt.h) */
> > >>      p = strchr(uri, '?');
> > >>      if (p) {
> > >>
> > >> How would you like this option to be made work in a way that can be
> > >> accepted in ffmpeg?
> > >> Is there a way to change the max packet size without this patch?
> > >>
> > > In your case, I don't think hard coding max packet size == 1316 is not
> > > a good idea in loopback device, and after deep in the srt
> > > library(https://github.com/Haivision/srt) source code, I think srt
> > > library need to fix the hardcode about packet size limition.
> >
> > I can't think of a scenario where limiting the packet size actually
> causes
> > problems, but if you insist on not limiting it in general, then the max
> > packet size should be settable using an option, same way it is for UDP.
> > (pkt_size option). I'd suggest using 1316 as default, because that
> > is the more common (and currently the only working) use case...
> >
> > Thanks,
> > Marton
> I agree with you, giving an option like pkt_size and using 1316 as the
> default in this case is a better way to fix this issue.
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