- From: Harald Alvestrand <harald@alvestrand.no>
- Date: Sun, 19 Jul 2015 10:19:41 +0200
- To: public-webrtc@w3.org
- Message-ID: <55AB5D9D.7020201@alvestrand.no>
On 07/19/2015 09:41 AM, Silvia Pfeiffer wrote: > On Sat, Jul 18, 2015 at 8:17 PM, Roman Shpount <roman@telurix.com> wrote: >> On Fri, Jul 17, 2015 at 7:33 PM, Silvia Pfeiffer <silviapfeiffer1@gmail.com> >> wrote: >>> >>>> I would think that having separate codec.name and codec.mimeType would >>>> be the best option. Based on >>>> http://www.iana.org/assignments/media-types/media-types.xhtml there are >>>> cases when there is a mismatch between the name and the mime type, such as >>>> "vnd.vivo" and "video/vnd-vivo". I hope no will ever need any of those >>>> codecs, but theoretically it is possible. >>> One piece of warning: duplicate information like this can lead to >>> conflicting information orifices in the two fields. I would prefer to just >>> use mime types as defined by IANA: >>> http://www.iana.org/assignments/rtp-parameters/rtp-parameters.xhtml. note >>> that these are the rtp mime types, not the file mime types, which is more >>> appropriate for WebRTC imho. >> I agree, redundant data can be dangerous, so only one field should be >> specified. I generally prefer to have the data parsed, so I would like to >> see separate codec.name, set just to name, and codec.kind set to "audio" or >> "video". Which brings the question, what about the extra encoding >> parameters, such as clock rates, channels, or bit rates supported? If mime >> types are used, these can be specified as mime type parameters such as >> "audio/L16;rate=16000", but analyzing them becomes even more difficult. I >> would like to see at least explicit codec.rate and codec.channel as well. > I'd suggest just going with a single mime type field to avoid having > to deal with all these issues. Mime type is defined as a single string > that a lot of things already understand and parse - ripping the bits > of the mime type field apart just means that for some things you have > to put them back together again and that seems more effort than it's > worth. For example, most mime types won't have a rater and a channel - > how are you going to fill these fields sensibly then? If you fill them > from some other information, how are you going to put the original > mime type field back together again? In http://w3c.github.io/webrtc-stats/#codec-dict* I broke out "channels", "clockRate, "codec" and "parameters" - because those are encoded differently in SDP from how they are encoded in a pure MIME type, so any app that wanted to match what's in SDP to what's in stats would have to break them up anyway - which limited the benefits to using the single-string form of the MIME type. ie Opus stereo at 48 kbits/sec with inband FEC m=audio a=rtpmap:101 opus/48000/2 a=fmtp:101 stereo=1; useinbandfec=1 while in a pure MIME type string it would be audio/opus; rate=48000; channels=2; stereo=1; useinbandfec=1 (with apologies for possible errors) > > S. > -- Surveillance is pervasive. Go Dark.
Received on Sunday, 19 July 2015 08:20:14 UTC