Another option is accessing the WebAudio context through the SDL_Audio
wrapper (if the OpenAL wrapper is not an option). I had to do this on iOS
Safari in order to 'unlock' audio on the first user input event.
Here's some copy-pasta from my code, this accesses the SDL wrapper to
initialize audio, and then accesses the embedded WebAudio context to create
and play an empty buffer (in an EM_ASM block). I think once you have the
WebAudio context you can do other things with it.
EM_BOOL SoundMgr::emscOnInputEvent(void* userData) {
// on iOS, WebAudio can only be initialized from a touch event,
// so we initialize soloud from within here, and tell the soundMgr
// that it is ok now to play audio
//
// https://paulbakaus.com/tutorials/html5/web-audio-on-ios/
SoundMgr* self = (SoundMgr*) userData;
if (!self->audioValid) {
EM_ASM(
SDL.openAudioContext();
if (SDL.webAudioAvailable()) {
var buffer = SDL.audioContext.createBuffer(1, 1, 22050);
var source = SDL.audioContext.createBufferSource();
source.buffer = buffer;
source.connect(SDL.audioContext.destination);
if (typeof source.start === "function") {
source.start(0);
}
else if (typeof source.noteOn == "function") {
source.onNote(0);
}
}
);
self->soloud.init();
// load all the delay load items that have piled up
for (const auto& item : self->delayLoadItems) {
self->initSource(item.sourceId, item.stream);
}
self->delayLoadItems.Clear();
self->audioValid = true;
}
return false;
}
#endif
Am Mittwoch, 23. August 2017 01:32:07 UTC+8 schrieb Brion Vibber:
>
> Web Audio is the JavaScript-side API that's being used; OpenAL serves as a
> C-side API in front of it.
>
> If you can get the Web Audio AudioContext object, you should be able to
> capture that via context.createMediaStreamDestination():
>
> https://developer.mozilla.org/en-US/docs/Web/API/AudioContext/createMediaStreamDestination
>
> https://developer.mozilla.org/en-US/docs/Web/API/MediaStreamAudioDestinationNode
>
> The node's "stream" property will be a MediaStream that you can send into
> RTC (at which point my knowledge of this system gets a lot fuzzier :D)
>
> -- brion
>
>
> On Tue, Aug 22, 2017 at 10:21 AM, Kai Kuehne <[email protected]
> <javascript:>> wrote:
>
>> Hi,
>> I'm using the MediaCapture-API to capture the video rendered
>> to a Canvas by emscripten to send it to another browser via
>> a RTCPeerConnection.
>>
>> How do I access the audio that is being played by emscripten
>> to also send it across the connection?
>>
>> I found a ticket [1] that mentions that one can export the AL object
>> and access the audio that way. Is this still relevant?
>>
>> To be honest, since I'm still in the early stages of development,
>> I don't know whether the audio is currently being handled by
>> OpenAL or WebAudio.
>>
>> Thanks!
>>
>> https://github.com/kripken/emscripten/issues/3599
>>
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