- From: Harald Alvestrand <harald@alvestrand.no>
- Date: Tue, 08 Nov 2011 15:05:09 +0100
- To: public-webrtc@w3.org
On 11/08/2011 11:57 AM, Stefan Håkansson LK wrote: > On 11/08/2011 01:15 AM, Harald Alvestrand wrote: >> Discharging a task taken on at the TPAC meeting, some possible words on >> what a media stream, a media stream track or a channel is.... >> >> This is based on the introduction section in section 3.1 of the current >> API editors' draft. >> >> The|MediaStream >> <http://dev.w3.org/2011/webrtc/editor/webrtc.html#mediastream>|interface >> is used to represent streams of media data, typically (but not >> necessarily) of audio and/or video content, e.g. from a local camera or >> a remote site. The data from a|MediaStream >> <http://dev.w3.org/2011/webrtc/editor/webrtc.html#mediastream>|object >> does not necessarily have a canonical binary form; for example, it could >> just be "the video currently coming from the user's video camera". This >> allows user agents to manipulate media streams in whatever fashion is >> most suitable on the user's platform. >> >> Each|MediaStream >> <http://dev.w3.org/2011/webrtc/editor/webrtc.html#mediastream>|object >> can represent zero or more tracks, in particular audio and video tracks. >> Tracks can contain multiple channels of parallel data; for example a >> single audio track could have nine channels of audio data to represent a >> 7.2 surround sound audio track. >> >> <new text below> >> >> All tracks in a MediaStream are presumed to be synchronized at some >> level. Different MediaStreams may or may not be synchronized. >> >> Each track represented by a|MediaStream >> <http://dev.w3.org/2011/webrtc/editor/webrtc.html#mediastream>|object >> has a corresponding|MediaStreamTrack >> <http://dev.w3.org/2011/webrtc/editor/webrtc.html#mediastreamtrack>|object. >> > > Nit: why do you say "represented by a MediaStream" in this section but > "in a MediaStream" in the previous one? "In a" sounds better to me. I copied this from "Each MediaStream object can represent zero or more tracks" 2 paragraphs further up. I would prefer to use language that says that a MediaStream contains zero or more tracks - as long as this doesn't confuse anyone when one track can be contained in multiple MediaStreams. > >> >> A MediaStreamTrack represents content comprising one or more channels, >> where the channels have a defined well known relationship to each other >> (such as a stereo or 5.1 audio signal), and may be encoded together for >> transmission as, for instance, an RTP payload type. >> >> A channel is the smallest unit considered in this API specification. >> >> <end new text> >> >> Would including this text help add any clarity after our discussions at >> TPAC? > > I think it helps. I am not convinced that the channels must be exposed > in any of the webrtc API's. The Audio API that Chris presented enables > access to the channels (in audio tracks) if there is a need to. Once we're sure we have consensus to reference the Audio group's Audio API, and that API is clear on how to deal with MediaStream tracks, I think we should add a paragraph saying that audio tracks can be manipulated by using the relevant Audio API functions. > > >
Received on Tuesday, 8 November 2011 14:05:50 UTC