[wdmaudiodev] Sampling Rate in Audio filter driver
- From: "Nick Lynch" <NickL@xxxxxxxxxxxxxx>
- To: <wdmaudiodev@xxxxxxxxxxxxx>
- Date: Mon, 31 Jul 2006 15:50:02 -0700
Hi,
First off, allow me to extend my thanks in advance to anyone who is able
to help me solve this problem. I appreciate your advice.
I am developing a product that captures all of the audio from a
specified process and re-transmits it to multiple clients over a
network. Since a noticeable delay is involved in the retransmission
process, we need to "mute" the targeted process, capture the audio data,
and replay the audio when it will be synchronized with our resending of
the audio packets.
I have developed a working audio filter driver that works to this extent
so far, with one catch - I am unable to programmatically determine the
bit rate from the filter driver. I install as an upper filter driver
directly above sysaudio. I have seen the references in the DDK to
KSPROPERTY_AUDIO_SAMPLING_RATE and
KSPROPERTY_AUDIO_DYNAMIC_SAMPLING_RATE, but never intercept requests or
sets for these properties while audio is playing. I usually get the
following KSPROPERTY requests during normal operation:
0 UNKNOWN
1 KSPROPERTY_AUDIO_LATENCY
2 KSPROPERTY_AUDIO_COPY_PROTECTION
3 KSPROPERTY_AUDIO_CHANNEL_CONFIG
4 KSPROPERTY_AUDIO_VOLUMELEVEL
5 KSPROPERTY_AUDIO_POSITION
6 KSPROPERTY_AUDIO_DYNAMIC_RANGE
7 KSPROPERTY_AUDIO_QUALITY
11 KSPROPERTY_AUDIO_MIX_LEVEL_CAPS
12 KSPROPERTY_AUDIO_MUX_SOURCE
13 KSPROPERTY_AUDIO_MUTE
14 KSPROPERTY_AUDIO_BASS
16 KSPROPERTY_AUDIO_TREBLE
21 KSPROPERTY_AUDIO_AGC
33 KSPROPERTY_AUDIO_CPU_RESOURCES
34 KSPROPERTY_AUDIO_STEREO_SPEAKER_GEOMETRY
35 KSPROPERTY_AUDIO_SURROUND_ENCODE
I have searched through every available buffer and have been unable to
determine how the bit rate is communicated to the audio device stack.
Any advice on the subject would be greatly appreciated.
Thank you in advance,
Nick
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