Re: Changing sample rate, Web Audio API, getUserMedia -- forward from [chromium-discuss]

I see. So OfflineAudioContext can do transcoding. Hope it will be exposed
soon. Thanks again Chris.

On Fri, Jan 11, 2013 at 2:39 AM, Chris Wilson <cwilso@google.com> wrote:

> The more problematic portion of this, He, is that I suspect your input
> device is giving a higher bitrate than you want anyway, so there's no
> getting around that you'll need to transcode your input stream (unless your
> input hardware really is giving a 16kHz mono stream) - it's just whether
> there would be built-in ways to do that, and right now, there aren't.  In
> our current design, the input is promoted to the output's hardware rate -
> it's not locked to 44kHz/stereo/16bit, that just happens to be what your
> output hardware is.
>
> Reducing from stereo to mono is easy, of course.  As I mentioned before,
> dropping from 44kHz to 22kHz is also easy; but if you really need to encode
> at specifically 16kHz, and don't want to write the interpolation code, you
> can always record the buffer in your normal AudioContext, then create an
> OfflineAudioContext at 16kHz mono 16bit, call offlineContext.createBuffer(
> 1, length, sampleRate ); and copy the data from your recorded buffer, then
> play in the offline context and encode the resulting buffer you're handed
> in oncomplete.
>
>
> On Thu, Jan 10, 2013 at 6:44 AM, He Shiming <heshiming@gmail.com> wrote:
>
>> Thanks Rob.
>>
>> But the so called 'StreamRecorder' is a bit confusing. A google search
>> came up nothing related. Though the sample code here:
>> https://dvcs.w3.org/hg/audio/raw-file/tip/webaudio/webrtc-integration.htmldid mention the '.record' method on LocalMediaStream interface, the actual
>> draft: http://dev.w3.org/2011/webrtc/editor/getusermedia.html mentioned
>> 'Apr 23 2012 - Remove MediaStreamRecorder' with no further explanation.
>>
>>
>> On Thu, Jan 10, 2013 at 6:47 PM, Robert O'Callahan <robert@ocallahan.org>wrote:
>>
>>> The StreamRecorder API proposal in public-media-capture is a better fit
>>> for this use-case. It will let developers record directly to WAV with
>>> minimal JS code, at whatever the native sample rate of the stream is.
>>>
>>> Rob
>>> --
>>> Jesus called them together and said, “You know that the rulers of the
>>> Gentiles lord it over them, and their high officials exercise authority
>>> over them. Not so with you. Instead, whoever wants to become great
>>> among you must be your servant, and whoever wants to be first must be
>>> your slave — just as the Son of Man did not come to be served, but to
>>> serve, and to give his life as a ransom for many.” [Matthew 20:25-28]
>>>
>>
>>
>>
>> --
>> Best regards,
>> He Shiming
>>
>
>


-- 
Best regards,
He Shiming