[FFmpeg-devel] [PATCH] Document the SAP muxer

[Martin Storsjö]

On Sat, 9 Oct 2010, Stefano Sabatini wrote:

> On date Saturday 2010-10-09 17:40:19 +0300, Martin Storsjo encoded:
> >  
> > + at section sap
> > +
> > +Session Announcement Protocol. This is not technically a protocol handler
> > +in libavformat, it is a muxer.
> 
> Maybe it may be a good idea to mention the RFC number, e.g. Session
> Announcement Protocol (RFC...).

Mentioned the RFC

> And BTW maybe this should be placed into a muxdemuxers.texi file, or
> even in two distinct files like for indevs/outdevs (not sure is a good
> idea in this case), but this can be done in a further patch.

I'm not sure I agree with that. Even if we'd have documentation on 
muxers/demuxers, I think this thematically belongs here, since it still 
describes network protocols, even if they're implemented as 
demuxers/muxers. But that's a different bikeshed issue, as long as it's 
documented somewhere, I don't have that much of an opinion.

> > +It is used for signalling of RTP streams, by announcing the SDP for the
> > +streams regularly on a separate port.
> > +
> > +The syntax for a SAP url given to the muxer is:
> > + at example
> > +sap://@var{destination}[:@var{port}][?@var{options}]
> > + at end example
> > +
> > +The RTP packets are sent to @var{destination} on port @var{port},
> > +or to port 5004 if no port is specified.
> > + at var{options} is a @code{&}-separated list. The following options
> > +are supported:
> > +
> > + at table @option
> > +
> > + at item announce_addr=@var{address}
> > +Specify the destination IP address for sending the announcements to.
> > +If omitted, the announcements are sent to the commonly used SAP
> > +announcement multicast address 224.2.127.254 (sap.mcast.net), or
> > +ff0e::2:7ffe if @var{destination} is an IPv6 address.
> > +
> > + at item announce_port=@var{port}
> > +Specify the port to send the announcements on, defaults to
> > +9875 if not specified.
> > +
> > + at item ttl=@var{ttl}
> > +Specify the time to live value for the announcements and RTP packets,
> > +defaults to 255.
> > +
> > + at item same_port=@var{0|1}
> > +If set to 1, send all RTP streams on the same port pair. If zero (the
> > +default), all streams are sent on unique ports, with each stream on a
> > +port 2 numbers higher than the previous.
> > +VLC/Live555 requires this to be set to 1, to be able to receive the stream.
> > + at end table
> > +
> 
> > +Example command lines:
> 
> I'd prefer:
> Example command lines follow.
> 
> as the incomplete sentence "Example command lines:" followed by
> "To broadcast a stream on the local subnet, for watching in VLC:"
> looks a little weird.

Ok, changed.

> > +
> > +To broadcast a stream on the local subnet, for watching in VLC:
> > +
> > + at example
> > +ffmpeg -re -i @var{input} -f sap sap://224.0.0.255?same_port=1
> > + at end example
> > +
> >  @section tcp
> 
> Rest of the patch looks good, thanks.

Ok, I'll apply it later if there are no other comments.

// Martin
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