Audio Mixer: Technical Specs

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WAVEFORMATEX::nChannels from 1 to 32. Can be different for different input/output pins.
 
WAVEFORMATEX::nChannels from 1 to 32. Can be different for different input/output pins.
  
Each input channel can be mixed with second channel of the same pin (for
+
Any channel(s) of any input pin(s) can be mixed with any other channel(s) of same or other input pin(s). Mixing coefficients can be changed in play time  
stereo inputs) or with any channel of another input pin (or several input
+
pins). Input channels can be switched on another output pin in play time  
+
 
also (without graph stop).
 
also (without graph stop).
  

Revision as of 17:17, 27 May 2010

Audio Mixer DirectShow specs.

Audio mixer is a standard DirectShow filter.

Number of input pins >= 1 (new pin will be added after connection of all free input pins).

Number of output pins >= 1 (new pin will be added after connection of all free output pins).

Input/output media type:

 majortype:
   MEDIATYPE_Audio
 subtype:
   MEDIASUBTYPE_PCM
 formattype:
   FORMAT_WaveFormatEx
 cbFormat, pbFormat:
   WAVEFORMATEX struct (wFormatTag = WAVE_FORMAT_PCM) for nChannels = 1 or 2 only
   WAVEFORMATEXTENSIBLE struct (Format.wFormatTag = WAVE_FORMAT_EXTENSIBLE)

Parameters of format:

WAVEFORMATEX::nSamplesPerSec and WAVEFORMATEX::wBitsPerSample: the same for all inputs/outputs.

WAVEFORMATEX::nChannels from 1 to 32. Can be different for different input/output pins.

Any channel(s) of any input pin(s) can be mixed with any other channel(s) of same or other input pin(s). Mixing coefficients can be changed in play time also (without graph stop).

Notes:

  • All input frequencies should be identical (resampling not implemented in current version).
  • After start of graph the media type of output pins cannot be changed (mono to stereo and vice versa).

The filter will have a COM interface and property page for set/get parameters of mixing (Input/channel -> Output/channel).

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