Implement Pipeline Audiomixer services for audio stream mixing

[rjhowell44]

New Pipeline symbolic constants

#define DSL_RESULT_PIPELINE_AUDIOMIX_GET_FAILED                     0x00080016
#define DSL_RESULT_PIPELINE_AUDIOMIX_SET_FAILED                     0x00080017

New Pipeline Audiomixer services

/**
 * @brief Returns the current enabled/disabled setting for the named Pipeline's
 * Audiomixer.
 * @param[in] name name of the Pipeline to query.
 * @param[out] enabled true if the Audiomixer is enabled, false if not.
 * @return DSL_RESULT_SUCCESS on successful query, one of 
 * DSL_RESULT_PIPELINE_RESULT on failure. 
 */
DslReturnType dsl_pipeline_audiomix_enabled_get(const wchar_t* name, 
    boolean* enabled);

/**
 * @brief Updates the current enabled/disabled setting for the named Pipeline's
 * Audiomixer. 
 * @param[in] name name of the Pipeline to update.
 * @param[in] enabled set to true to enable the Audiomixer, false to disable.
 * @return DSL_RESULT_SUCCESS on successful update, one of 
 * DSL_RESULT_PIPELINE_RESULT on failure. 
 */
DslReturnType dsl_pipeline_audiomix_enabled_set(const wchar_t* name, 
    boolean enabled);

/**
 * @brief Gets the Audiomixer's mute enabled setting for a specific Audio Source.
 * @param[in] name name of the Pipeline to query.
 * @param[in] source name of the Audio Source for the mute enabled setting.
 * @param[out] enabled if true, then the Audiomixer's sink pad connected to
 * the named Audio Source is currently muted - or will be muted when the pipeline 
 * is played.
 * @return DSL_RESULT_SUCCESS on successful update, one of 
 * DSL_RESULT_PIPELINE_RESULT on failure. 
 */
DslReturnType dsl_pipeline_audiomix_mute_enabled_get(const wchar_t* name, 
    const wchar_t* source, boolean* enabled);

/**
 * @brief Sets the Audiomixer's mute enabled setting for a specific Audio Source.
 * @param[in] name name of the Pipeline to update.
 * @param[in] source name of the Audio Source to mute or unmute.
 * @param[in] enabled set to true to mute the Audiomixer's sink pad connected to
 * the named Audio Source, false to unmute.
 * @return DSL_RESULT_SUCCESS on successful update, one of 
 * DSL_RESULT_PIPELINE_RESULT on failure. 
 */
DslReturnType dsl_pipeline_audiomix_mute_enabled_set(const wchar_t* name, 
    const wchar_t* source, boolean enabled);

/**
 * @brief Sets the Audiomixer's mute enabled setting for a null terminated list of
 * Audio Sources.
 * @param[in] name name of the Pipeline to update.
 * @param[in] sources null-terminated list of Audio Sources to mute or unmute.
 * @param[in] enabled set to true to mute the Audiomixer's sink pads connected to
 * the named Audio Sources, false to unmute.
 * @return DSL_RESULT_SUCCESS on successful update, one of 
 * DSL_RESULT_PIPELINE_RESULT on failure. 
 */
DslReturnType dsl_pipeline_audiomix_mute_enabled_set_many(const wchar_t* name, 
    const wchar_t** sources, boolean enabled);

/**
 * @brief Gets the Audiomixer's volume setting for a specific Audio Source.
 * @param[in] name name of the Pipeline to query.
 * @param[in] source name of the Audio Source for the volume setting.
 * @param[out] volume the volume that is assigned to the Audiomixer's 
 * sink pad connected to the named Audio Source, between 0.0 and 10.0.
 * Default = 1.0
 * @return DSL_RESULT_SUCCESS on successful update, one of 
 * DSL_RESULT_PIPELINE_RESULT on failure. 
 */
DslReturnType dsl_pipeline_audiomix_volume_get(const wchar_t* name, 
    const wchar_t* source, double* volume);

/**
 * @brief Sets the Audiomixer's volume setting for a specific Audio Source.
 * @param[in] name name of the Pipeline to update.
 * @param[in] source name of the Audio Source to set the volume for.
 * @param[in] volume a value between 0.0 and 10.0. Default = 1.0.
 * @return DSL_RESULT_SUCCESS on successful update, one of 
 * DSL_RESULT_PIPELINE_RESULT on failure. 
 */
DslReturnType dsl_pipeline_audiomix_volume_set(const wchar_t* name, 
    const wchar_t* source, double volume);
 
/**
 * @brief Sets the Audiomixer's volume setting for a null-terminated list of
 * Audio Sources.
 * @param[in] name name of the Pipeline to update.
 * @param[in] sources null terminated list of the Audio Sources to set the 
 * volume for.
 * @param[in] volume a value between 0.0 and 10.0. Default = 1.0.
 * @return DSL_RESULT_SUCCESS on successful update, one of 
 * DSL_RESULT_PIPELINE_RESULT on failure. 
 */
DslReturnType dsl_pipeline_audiomix_volume_set_many(const wchar_t* name, 
    const wchar_t** sources, double volume);