Supported Codecs

Appendix: Supported Codecs

This appendix contains the list of supported codecs for the QNX Audio Architecture. A supported codec in these terms is a codec for which QNX Software Systems has produced a Dynamic Linked Library (DLL) to control it.

The currently supported codecs include:

Audio Codec 97 (AC97)
AK4531

We support a codec only if it's a standardized part with a detailed specification, and it's used in audio platforms of use to us and our customers.

As well as providing analog audio mixer functions, a codec may also provide other callback functions of use to the audio driver, such as Sample Rate Conversion (SRC) or S/PDIF. Handling PCM Audio Data chapter.

To use one of these codecs, call ado_mixer_dll() in your Audio HW DLL's ctrl_init() function. For more information, see "Using a standard mixer DLL" in the Handling Analog Audio Data chapter.

The sections below indicate what arguments you need to pass to ado_mixer_dll().

Audio Codec 97 (AC97)

DLL Name

Pass "ac97" as the mixer_dll argument to ado_mixer_dll().

Header File

<mixer/ac97_dll.h>

Parameter Structure

This structure holds pointers to the callback functions that you need to provide for the mixer DLL to call:

typedef
struct  ado_mixer_dll_params_ac97
{
  HW_CONTEXT_T  *hw_context;
  uint16_t      (*read) (HW_CONTEXT_T *hw_context,
                         uint16_t reg);
  void          (*write) (HW_CONTEXT_T *hw_context,
                          uint16_t reg, uint16_t val);
  int32_t       (*init) (HW_CONTEXT_T *hw_context);
  void          (*destroy) (HW_CONTEXT_T *hw_context);
} ado_mixer_dll_params_ac97_t;

The members include:

hw_context: A pointer to a structure that you can use for any context-sensitive data that your driver needs. It's used only as an argument for the function calls.
read(): Read the given ac97 register.
write(): Write the given value into the given ac97 register.
init(): The upper layer of the driver calls this function after the codec has been initialized. Use this callback to make any last-minute adjustments.
destroy(): The upper layer of the driver calls this function just before the DLL terminates. In general, you should use it to undo anything init() did.

Pass a pointer to a ado_mixer_dll_params_ac97_t structure as the params argument to ado_mixer_dll().

Supported Device Controls

This structure holds pointers to the callback functions, provided by the mixer DLL, that your Audio HW DLL can call to control the device:

enum ac97_SRC
{
  AC97_FRONT_DAC_SRC,
  AC97_SURR_DAC_SRC,
  AC97_LFE_DAC_SRC,
  AC97_LR_ADC_SRC,
};

typedef
struct  ado_mixer_dll_callbacks_ac97
{
  MIXER_CONTEXT_T  *mix_context;
  int32_t          (*SRC_test) (MIXER_CONTEXT_T * mix_context,
                                enum ac97_SRC src,
                                ado_pcm_cap_t * caps);
  int32_t          (*SRC_set) (MIXER_CONTEXT_T * mix_context,
                               enum ac97_SRC src,
                               uint32_t * rate);
}
ado_mixer_dll_callbacks_ac97_t;

The members include:

mix_context: A pointer to a structure that the codec uses for any context-sensitive data that it needs. Use it only as an argument for the function calls defined in this structure.
SRC_test: Checks which sample rates are supported for the src sample rate converter and updates the information in the given ado_pcm_cap_t structure.
SRC_set: Sets the sample rate for the src sample rate converter.

Pass a pointer to a ado_mixer_dll_callbacks_ac97_t structure as the callbacks argument to ado_mixer_dll().

References

http://developer.intel.com/ial/scalableplatforms/audio/index.htm

ftp://download.intel.com/ial/scalableplatforms/ac97r22.pdf

AK4531

typedef
struct  ado_mixer_dll_params_ak4531
{
  HW_CONTEXT_T  *hw_context;
  void          (*write) (HW_CONTEXT_T *hw_context,
                          uint16_t reg, uint16_t val);
  void          (*destroy) (HW_CONTEXT_T *hw_context);
} ado_mixer_dll_params_ak4531_t;

The members include:

hw_context: A pointer to a structure that you can use for any context-sensitive data that your driver needs. It's used only as an argument for the function calls.
write(): Write the given value into the given ak4531 register.
destroy(): The upper layer of the driver calls this function just before the DLL terminates.

Pass a pointer to a ado_mixer_dll_params_ak4531_t structure as the params argument to ado_mixer_dll().

Supported Device Controls

None; pass a NULL pointer as the callbacks argument to ado_mixer_dll().

Reference

http://www.akm.com/ProductPages/ak4531.html

Museum

Supported Codecs