[wdmaudiodev] Re: Retrieving WAVEFORMATEX from IAudioSessionControl
- From: Dadi <dadiku@xxxxxxxxx>
- To: wdmaudiodev@xxxxxxxxxxxxx
- Date: Wed, 17 Dec 2014 22:29:57 +0200
Hi Matthew,
Yes we know that but we are processing only global (MFX) and our effects
must all reside in the same APO instance so in surround we get only 5.1 =>
5.1.
In addition we are also working on new effects (not upmix) and we must have
the WAVESFORMTEX of the active streams.
The possibilities we currently have are:
- We can write SFX APOs that always do full bypass only for that matter -
gather the WAVESFORMATEX information and copy it to a shared memory or some
other IPC mechanism so the MFX APO can read read it.
- We can also get the assistance of the codec vendor (with private API) to
give us this information to overcome this limitation but we prefer to have
a better way for this.
Is there any way to resolve it gracefully?
Thank you,
Dadi
2014-12-17 20:08 GMT+02:00 Matthew van Eerde <
Matthew.van.Eerde@xxxxxxxxxxxxx>:
> It’s too late to do any kind of stream-intelligent upmixing in a render
> GFX, MFX or EFX. Everything’s already been channel-converted and mixed
> together by the time it gets to you. If you want to do intelligent channel
> matrixing per stream, you need an SFX.
>
>
>
> Render SFXes (and only render SFXes) can support multiple input formats,
> even with differing channel counts. So on a 5.1 output you can do:
>
> 1. 2.0 => 5.1 (upmix)
>
> 2. 5.1 => 5.1
>
>
>
> And on a 2.0 output, you can do:
>
> 1. 2.0 => 2.0
>
> 2. 5.1 => 2.0 (downmix)
>
>
>
> *From:* wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:
> wdmaudiodev-bounce@xxxxxxxxxxxxx] *On Behalf Of *Dadi
> *Sent:* Tuesday, December 16, 2014 6:02 AM
> *To:* wdmaudiodev@xxxxxxxxxxxxx
> *Subject:* [wdmaudiodev] Re: Retrieving WAVEFORMATEX from
> IAudioSessionControl
>
>
>
> Hi Matthew,
>
> Our global APO needs that information for its processing logic.
>
> E.g. for doing surround upmix we need to know the channel count of all
> open sessions. That way we can find if an app opened a stereo channel to
> play audio (and so the APO should do upmix) or if an app is playing full
> surround and intentionally only two channels are active (e.g. can happen
> while a movie is played) and in this case we should NOT do any upmix in the
> APO.
>
> Because there can be many audio sessions simultaneous then we will take
> the minimum or maximum values for reference.
>
> The above is only one example and there are other cases in which our APO
> needs to know the original format.
>
> Windows API allows us to enumerate all the active audio sessions (we can
> filter it per endpoint) and get IAudioSessionControl for each session but
> we need to use it to get the active WAVESFORMATEX.
>
>
>
> Note - we do not have any SFX APOs, only global.
>
> Is there any way to resolve this?
>
> Thank you,
>
> Dadi
>
>
>
>
>
>
>
> 2014-12-15 18:58 GMT+02:00 Matthew van Eerde <
> Matthew.van.Eerde@xxxxxxxxxxxxx>:
>
> Conceptually, an audio session (IAudioSessionControl) is an (app,
> endpoint) pair.
>
>
>
> An app can have zero or more active streams (IAudioClient) on a given
> endpoint at any given time.
>
>
>
> The stream has an associated WAVEFORMATEX (what was passed to
> IAudioClient::Initialize) but there’s no way to retrieve it from the
> IAudioClient.
>
>
>
> There is also no way to get the list of active IAudioClients from an
> IAudioSessionControl.
>
>
>
> What is the larger problem you’re trying to solve?
>
>
>
> *From:* wdmaudiodev-bounce@xxxxxxxxxxxxx [mailto:
> wdmaudiodev-bounce@xxxxxxxxxxxxx] *On Behalf Of *Dadi
> *Sent:* Sunday, December 14, 2014 11:21 AM
> *To:* wdmaudiodev@xxxxxxxxxxxxx
> *Subject:* [wdmaudiodev] Retrieving WAVEFORMATEX from IAudioSessionControl
>
>
>
> Hi,
>
> Is it possible to retrieve the audio session format (WAVEFORMATEX) from a
> given pointer to an active IAudioSessionControl?
>
> Thank you,
>
> Dadi
>
>
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