- From: Wei, James <james.wei@intel.com>
- Date: Thu, 29 Mar 2012 02:05:43 +0000
- To: "public-audio@w3.org" <public-audio@w3.org>
- Message-ID: <668CBE60026FE04AB5523C7C3CCB00F8074A28@SHSMSX101.ccr.corp.intel.com>
From: Stefan Hakansson LK <stefan.lk.hakansson@ericsson.com> Date: Wed, 28 Mar 2012 20:54:38 +0200 Message-ID: <4F735E6E.7070706@ericsson.com> To: "public-webrtc@w3.org" <public-webrtc@w3.org> I've spent some time looking at the Web Audio API [1] since the Audio WG have put out a call for review [2]. As starting point I used the related reqs from our use-case and req document [3]: F13 The browser MUST be able to apply spatialization effects to audio streams. F14 The browser MUST be able to measure the level in audio streams. F15 The browser MUST be able to change the level in audio streams. with the accompanying API reqs: A13 The Web API MUST provide means for the web application to apply spatialization effects to audio streams. A14 The Web API MUST provide means for the web application to detect the level in audio streams. A15 The Web API MUST provide means for the web application to adjust the level in audio streams. A16 The Web API MUST provide means for the web application to mix audio streams. Looking at the Web Audio API, and combining it with the MediaStream concept we use, I come to the following understanding: 1) To make the audio track(s) of MediaStream(s) available to the Web Audio processing blocks, the The MediaElementAudioSourceNode Interface would be used. 2) Once that is done, the audio is available to the Web Audio API toolbox, and anything we have requirements on can be done 3) When the processing has been done (panning, measure level, change level, mix) the audio would be played using an AudioDestinationNode Interface What is unclear to me at present, is how synchronization would work. So far we have been discussing in terms of that all tracks in a MediaStream are kept in sync; but what happens when the audio tracks are routed to another set of tools, and not played in the same (video) element as the video? Another take away is that the processing can only happen in the browser that is going to play the audio, since there is no way to go from an AudioNode to a MediaStream or MediaStreamTrack. Anyone else that has looked into the Web Audio API? And any other conclusions? I think we should give feedback from this WG (as we have some reqs that are relevant). Br, Stefan [1] http://www.w3.org/TR/2012/WD-webaudio-20120315/ [2] http://lists.w3.org/Archives/Public/public-webrtc/2012Mar/0072.html [3] http://datatracker.ietf.org/doc/draft-ietf-rtcweb-use-cases-and-requirements/?include_text=1 Best Regards James
Received on Thursday, 29 March 2012 02:08:03 UTC