Several little issues in exported SDP files for ancillary data

[garethsb]

Example exported SDP file for ancillary data:

v=0
o=- 1 1 IN IP4 0.0.0.0
s=LIST Generated SDP
i=Ancillary flow, GENERATED by EBU-LIST (some params like media clock are hardcoded).
t=0 0
a=recvonly
m=ancillary 50040 RTP/AVP 100
c=IN IP4 239.43.24.1/32
a=mediaclk:direct=0
a=ts-refclk:ptp=IEEE1588-2008:00-00-00-00-00-00-00-00:00
a=rtpmap:100 smpte291/90000
a=source-filter:incl IN IP4 239.43.24.1 192.168.23.24
a=fmtp:100 DID_SDID={0x96,0x96};

1. Shouldn't it have m=video... not ancillary, as the correct media type is video/smpte291?
   Fix presumably needed here: https://github.com/ebu/pi-list/blob/9c500b2ffdbb16b2b3e83c7ed3d4c181ca7a6d6b/cpp/libs/rtp/lib/src/ebu/list/sdp/sdp_writer.cpp#L49-L50
2. a=ts-refclk: format isn't valid according to RFC 7273 Section 4.8, is it?
   If a domain number is intended, perhaps the fix would be to change trailing :00 into :domain-nmbr=0 at: https://github.com/ebu/pi-list/blob/9c500b2ffdbb16b2b3e83c7ed3d4c181ca7a6d6b/cpp/libs/rtp/lib/src/ebu/list/sdp/sdp_writer.cpp#L67
3. DID_SDID looks plausible but this stream had SMPTE ST 12 timecode (60h, 60h), so I think the number formatting is incorrect.
   Fix presumably needed here because std::to_string only does decimal output: https://github.com/ebu/pi-list/blob/9c500b2ffdbb16b2b3e83c7ed3d4c181ca7a6d6b/cpp/libs/st2110/lib/src/ebu/list/st2110/d40/anc_description.cpp#L76-L78

[garethsb]

2. a=ts-refclk: format isn't valid according to RFC 7273 Section 4.8, is it? If a domain number is intended, perhaps the fix would be to change trailing :00 into :domain-nmbr=0 at: https://github.com/ebu/pi-list/blob/9c500b2ffdbb16b2b3e83c7ed3d4c181ca7a6d6b/cpp/libs/rtp/lib/src/ebu/list/sdp/sdp_writer.cpp#L67

I just remembered I'd seen errata for RFC 7273 that changed the ABNF to match the examples.

Based on https://www.rfc-editor.org/errata/eid4450 the fix for this issue is only to change the trailing :00 into :0 (single digit).

[pedro-alves-ferreira]

Hello Gareth,

Many thanks for pointing this out and for the thorough feedback. We'll correct these issues soon.

Regards,

Pedro

[pedro-alves-ferreira]

Hi Gareth,

These should have been fixed now. I'd appreciate if you could check it and close the issue.

Thanks!

Pedro