Re: 96KHz and 192KHz Sampling Frequencies

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Hi R. de Gravelaine,

Thank You Very Much for your continuous help.

I noticed that in the current wavedev2 returns the below WAVEOUTEXTCAPS

case WODM_GETEXTDEVCAPS:
{
LPVOID pCaps = (PVOID)dwParam1;
DWORD dwSize = dwParam2;
static const WAVEOUTEXTCAPS wec =
{
0xFFFF, // max number
of hw-mixed streams
0xFFFF, // available HW
streams
0, //
preferred sample rate for software mixer (0 indicates no preference)
6, //
preferred buffer size for software mixer (0 indicates no preference)
0, //
preferred number of buffers for software mixer (0 indicates no
preference)
8000, // minimum
sample rate for a hw-mixed stream
48000 // maximum
sample rate for a hw-mixed stream
};

It looks no SW Mixer being used in our current wavedev2 driver. Only
differnece in those settings is, in the original post preferred sampling rate
set to 0. In our case preferred sampling rate set to 6.

Thank You & Regards,
GSR

"R. de Gravelaine" wrote:

Hi,

Another outstanding thread is
http://groups.google.fr/group/microsoft.public.windowsce.platbuilder/browse_frm/thread/12ee87d5018dd784/8f086e5bc3145d69

This can give you indications on how to disable the Software Mixer.

HTH
Remi



GSR a écrit :
Hi,

Yes, I have an audio device which can support till 192 KHz and the output is
dostorted when I used a 192 KHz audio raw file, SW Mixer using a SamplingRate
of 44.1 KHz and HW Codec also using a SampleRate of 44.1 KHz (I2S Word Clock
= 44.1 KHz).

I understand what you are saying, in that case when we use a 8 KHz audio raw
file, it's also not a multiple of 44.1 KHz, but the audio output works just
fine.

I read the articles which are in the weblinks provided by the R. de
Gravelaine. Let me read them once again.

With no SampleRate registry entry (SW Mixer is running at a SampleRate of
44.1KHz), and when HW Codec is running with 44.1 KHz sampling frequency, I
have verified the following sampling frequencies 8KHz, 11.025KHz, 16KHz,
22.05KHz, 32KHz, 44.1KHz and 48KHz. I don't see any issues with playback and
recording for those frequencies. As soon as I use either 96KHz / 192KHz
sampling rates playback output is distorted.

Thank You & Regards,
GSR


"Henrik Viklund [eMVP]" wrote:

OK, now you lost me... Can't say I've used the software mixer much in
CE (never above 48kHz) but are you saying you have audio hardware that
can do up to 192kHz/24bit but you use a software mixer to downsample
to 44.1kHz/16bit? Do you get no output whatsoever or is it distorted?
In the end, decent audio sample rate conversion is pretty resource-
consuming, especially when converting between rates that are not
multiples of eachother.

Henrik Viklund
Prevas AB

On 19 Nov, 06:59, GSR <G...@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Hello R. de Gravelaine,

Thank You Very Much for the reply.

As you suggested I changed the SampleRate registry entry for Software Mixer
to 8KHz (0x1F40). So, I have changed the Codec Sampling Frequency to 8KHz..

When I played a raw wav file with this configuration, it didn't work, I can
see audio bar progresses on Windows Media Player. But, the Audio whatever I
hear is not clear. Which is not so when we used 44.1KHz sampling rate with
the Hardware Audio Codec and No entry for "SampleRate" in registry.

I am using a release build. I will try a Debug build, probably I will get
some Log from SW Mixer.

Still one concept was not clear. I understood that Wavedev2 can do Sample
Rate Conversion. If SW Mixer does Sample Rate Conversion based on
"SampleRate" registry entry then to which rate the Wavedev2 Sample Rate
Convertes the audio input/output. Is it does on the same "SampleRate"
registry entry ?

The check whatever you suggested, that I haven't tried. Once I complete that
I will update about that here.

Thank You & Regards,
GSR



"R. de Gravelaine" wrote:
Hi,
Did you try to tune the Software Mixer to accommodate the hardware
sampling rate? (http://msdn.microsoft.com/en-us/library/ee483245.aspx)
For instance, to operate the Software Mixer at 96000 Hz, change the AC44
(44100) SampleRate value to 17700 (96000):
[HKEY_LOCAL_MACHINE\Audio\SoftwareMixer]
"SampleRate"=dword:17700
The Software Mixer is supposed to convert all inputs to the SampleRate
given in the Registry. It works well at least for rates up to 48000 Hz
(I checked it) but maybe does it have some difficulties to downsample
its input when the rates become 'high'?
In any case, one check I would do would be to calculate the rate at the
output of the Software Mixer, i.e. at the input of the driver write
routines. This should be feasible by counting the bytes and the time
elapsed between OPEN and STOP.
HTH
Remi
GSR a écrit :
Hi Henrik Viklund,
Thank You Very Much for your reply.
I have a OMAP Hardware which is interfaced with a TI's Hardware Audio Codec.
The TI's Hardware Audio Codec does supports 96KHz and 192KHz sampling rates.
The audio model being implemented is Wavedev2.
Either the wavedev2 mixer / Software Mixer which is running in waveapi.dll
can do Sample Rate Conversion, we are using a sample rate of 44.1KHz always
to the Hardware Auido Codec.
I have verified that, when the hardware audio codec is using 44.1KHz
sampling rate all the audio files (.wav format) whose sample rate is less
than or equal to 48KHz are played with out any issues.
When I tried 96KHz/192KHz raw audio files (.wav), they are not played
properly with the TI's hardware audio codec.
So, I thought of exercising the same thing on Device Emulator as it does
supports audio driver with wavedev2 implementation.
As of know I don't have any idea how to proceed in debugging with this issue.
Thank You & Regards,
GSR
"Henrik Viklund [eMVP]" wrote:
IIRC the emulator BSP I2S clock speed is hardcoded to 44.1kHz. The
emulator emulates an actual SMDK2410 eval board and while I beleave
the real SMDK2410 hardware is capable of 96 kHz, the emulator is not..
If you really need to do 96/192kHz audio tests, you're better off
doing those tests on real hardware with proper hardware support.
Henrik Viklund
Prevas AB
On 6 Nov, 11:31, GSR <G...@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Hi,
I am using Windows CE 6.0 R2.
I built a Windows CE Emulator PDA device in Debig Build.
When I used 96KHz / 192KHz audio .wav files they do not play properly.
Is there any limitation in Windows CE that it can support a range of
sampling frequencies only ?
Is it possible to give support of those sampling frequencies ?
Thank You & Regards,
GSR
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