Previous

Next

Function USBAudioDumpUnits

USBAudioDumpUnits writes information about all units of an Audio function or device to a string:

int USBAudioDumpUnits(int AudioID, char * s, DWORD Flags);

Parameters

AudioID

Audio ID value previously returned by function USBAudioGetInfo.

s

Pointer to a string to receive the data. The buffer should typically have a size of no less than 2k.

Flags

Zero or flag USB_DUMP_ALL. If USB_DUMP_ALL is specified, USBAudioDumpUnits will list all units in the specified audio device, and not only those associated with the specified audio function.

return value

RTU_SUCCESS or a negative error code.

This function is intended to debugging purposes. The interpretation of the returned string requires good knowledge of the USB Audio specification.

Example

INPUT_TERMINAL(1):* OUTPUT_TERMINAL(6):9, 
FEATURE_UNIT[MVL](9):15, MIXER_UNIT(15):1,13,

Each unit is listed with its type name and unit ID in parenthesis. A list of unit IDs follows after a colon specifying the units from which this unit receives its input. The terminal associated with the USB endpoint of the specified audio function is followed by a star. For feature units, each implemented feature is represented with a letter in brackets (M = Mute, V = Volume, B = Bass, I = Mid, T = Treble, G = Graphic Equalizer, A = Automatic Gain, D = Delay, S = Bass Boost, L = Loudness).

The example above shows the speaker part of an audio headset. Unit 1 is the audio function's USB endpoint. It receives its data from the outside (i.e., the USB bus). The audio signal then passes to mixer unit 15 which also receives another audio data stream from unit 13 which is part of a different audio function (which would also be displayed if USB_DUMP_ALL is specified). The data then goes to feature unit 9 which supports features Mute, Volume, and Loudness. Finally, the sound passes to unit 6, which is a speaker.

Function USBAudioTranslate