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Use Case Interface

Macros

#define SND_USE_CASE_VERB_INACTIVE   "Inactive"
#define SND_USE_CASE_VERB_HIFI   "HiFi"
#define SND_USE_CASE_VERB_HIFI_LOW_POWER   "HiFi Low Power"
#define SND_USE_CASE_VERB_VOICE   "Voice"
#define SND_USE_CASE_VERB_VOICE_LOW_POWER   "Voice Low Power"
#define SND_USE_CASE_VERB_VOICECALL   "Voice Call"
#define SND_USE_CASE_VERB_IP_VOICECALL   "Voice Call IP"
#define SND_USE_CASE_VERB_ANALOG_RADIO   "FM Analog Radio"
#define SND_USE_CASE_VERB_DIGITAL_RADIO   "FM Digital Radio"
#define SND_USE_CASE_DEV_NONE   "None"
#define SND_USE_CASE_DEV_SPEAKER   "Speaker"
#define SND_USE_CASE_DEV_LINE   "Line"
#define SND_USE_CASE_DEV_HEADPHONES   "Headphones"
#define SND_USE_CASE_DEV_HEADSET   "Headset"
#define SND_USE_CASE_DEV_HANDSET   "Handset"
#define SND_USE_CASE_DEV_BLUETOOTH   "Bluetooth"
#define SND_USE_CASE_DEV_EARPIECE   "Earpiece"
#define SND_USE_CASE_DEV_SPDIF   "SPDIF"
#define SND_USE_CASE_DEV_HDMI   "HDMI"
#define SND_USE_CASE_MOD_CAPTURE_VOICE   "Capture Voice"
#define SND_USE_CASE_MOD_CAPTURE_MUSIC   "Capture Music"
#define SND_USE_CASE_MOD_PLAY_MUSIC   "Play Music"
#define SND_USE_CASE_MOD_PLAY_VOICE   "Play Voice"
#define SND_USE_CASE_MOD_PLAY_TONE   "Play Tone"
#define SND_USE_CASE_MOD_ECHO_REF   "Echo Reference"
#define SND_USE_CASE_TQ_MUSIC   "Music"
#define SND_USE_CASE_TQ_VOICE   "Voice"
#define SND_USE_CASE_TQ_TONES   "Tones"

Typedefs

typedef struct snd_use_case_mgr snd_use_case_mgr_t

Functions

char * snd_use_case_identifier (const char *fmt,...)
 Create an identifier.
int snd_use_case_free_list (const char *list[], int items)
 Free a string list.
int snd_use_case_get_list (snd_use_case_mgr_t *uc_mgr, const char *identifier, const char **list[])
 Obtain a list of entries.
int snd_use_case_get (snd_use_case_mgr_t *uc_mgr, const char *identifier, const char **value)
 Get current - string.
int snd_use_case_geti (snd_use_case_mgr_t *uc_mgr, const char *identifier, long *value)
 Get current - integer.
int snd_use_case_set (snd_use_case_mgr_t *uc_mgr, const char *identifier, const char *value)
 Set new.
int snd_use_case_mgr_open (snd_use_case_mgr_t **uc_mgr, const char *card_name)
 Open and initialise use case core for sound card.
int snd_use_case_mgr_reload (snd_use_case_mgr_t *uc_mgr)
 Reload and re-parse use case configuration files for sound card.
int snd_use_case_mgr_close (snd_use_case_mgr_t *uc_mgr)
 Close use case manager.
int snd_use_case_mgr_reset (snd_use_case_mgr_t *uc_mgr)
 Reset use case manager verb, device, modifier to deafult settings.

Detailed Description

The ALSA Use Case manager interface. See ALSA Use Case Interface page for more details.

ALSA Use Case Interface

The use case manager works by configuring the sound card ALSA kcontrols to change the hardware digital and analog audio routing to match the requested device use case. The use case manager kcontrol configurations are stored in easy to modify text files.An audio use case can be defined by a verb and device parameter. The verb describes the use case action i.e. a phone call, listening to music, recording a conversation etc. The device describes the physical audio capture and playback hardware i.e. headphones, phone handset, bluetooth headset, etc.It's intended clients will mostly only need to set the use case verb and device for each system use case change (as the verb and device parameters cover most audio use cases).However there are times when a use case has to be modified at runtime. e.g. In order to allow asynchronous runtime use case adaptations, we have a third optional modifier parameter that can be used to further configure the use case during live audio runtime.This interface allows clients to :-

Macro Definition Documentation

#define SND_USE_CASE_DEV_BLUETOOTH   "Bluetooth"

Bluetooth Device

#define SND_USE_CASE_DEV_EARPIECE   "Earpiece"

Earpiece Device

#define SND_USE_CASE_DEV_HANDSET   "Handset"

Handset Device

#define SND_USE_CASE_DEV_HDMI   "HDMI"

HDMI Device

#define SND_USE_CASE_DEV_HEADPHONES   "Headphones"

Headphones Device

#define SND_USE_CASE_DEV_HEADSET   "Headset"

Headset Device

#define SND_USE_CASE_DEV_LINE   "Line"

Line Device

#define SND_USE_CASE_DEV_NONE   "None"

None Device

#define SND_USE_CASE_DEV_SPDIF   "SPDIF"

SPDIF Device

#define SND_USE_CASE_DEV_SPEAKER   "Speaker"

Speaker Device

#define SND_USE_CASE_MOD_CAPTURE_MUSIC   "Capture Music"

Capture Music Modifier

#define SND_USE_CASE_MOD_CAPTURE_VOICE   "Capture Voice"

Capture Voice Modifier

#define SND_USE_CASE_MOD_ECHO_REF   "Echo Reference"

Echo Reference Modifier

#define SND_USE_CASE_MOD_PLAY_MUSIC   "Play Music"

Play Music Modifier

#define SND_USE_CASE_MOD_PLAY_TONE   "Play Tone"

Play Tone Modifier

#define SND_USE_CASE_MOD_PLAY_VOICE   "Play Voice"

Play Voice Modifier

#define SND_USE_CASE_TQ_MUSIC   "Music"

TQ - Tone Quality

The interface allows clients to determine the audio TQ required for each use case verb and modifier. It's intended as an optional hint to the audio driver in order to lower power consumption. Music Tone Quality

#define SND_USE_CASE_TQ_TONES   "Tones"

Tones Tone Quality

#define SND_USE_CASE_TQ_VOICE   "Voice"

Voice Tone Quality

#define SND_USE_CASE_VERB_ANALOG_RADIO   "FM Analog Radio"

FM Analog Radio Verb

#define SND_USE_CASE_VERB_DIGITAL_RADIO   "FM Digital Radio"

FM Digital Radio Verb

#define SND_USE_CASE_VERB_HIFI   "HiFi"

HiFi Verb

#define SND_USE_CASE_VERB_HIFI_LOW_POWER   "HiFi Low Power"

HiFi Low Power Verb

#define SND_USE_CASE_VERB_INACTIVE   "Inactive"

Inactive Verb

#define SND_USE_CASE_VERB_IP_VOICECALL   "Voice Call IP"

Voice Call IP Verb

#define SND_USE_CASE_VERB_VOICE   "Voice"

Voice Verb

#define SND_USE_CASE_VERB_VOICE_LOW_POWER   "Voice Low Power"

Voice Low Power Verb

#define SND_USE_CASE_VERB_VOICECALL   "Voice Call"

Voice Call Verb


Typedef Documentation

typedef struct snd_use_case_mgr snd_use_case_mgr_t

use case container


Function Documentation

int snd_use_case_free_list ( const char *  list[],
int  items 
)

Free a string list.

Parameters:
listThe string list to free
itemsCount of strings
Returns:
Zero if success, otherwise a negative error code
int snd_use_case_get ( snd_use_case_mgr_t uc_mgr,
const char *  identifier,
const char **  value 
)

Get current - string.

Parameters:
uc_mgrUse case manager
identifier
valueValue pointer
Returns:
Zero if success, otherwise a negative error code

Note: The returned string is dynamically allocated, use free() to deallocate this string. (Yes, the value parameter shouldn't be marked as "const", but it's too late to fix it, sorry about that.)

Known identifiers:

  • NULL - return current card
  • _verb - return current verb
  • _file - return configuration file loaded for current card
  • [=]{NAME}[/[{modifier}|{/device}][/{verb}]]
    • value identifier {NAME}
    • Search starts at given modifier or device if any, else at a verb
    • Search starts at given verb if any, else current verb
    • Searches modifier/device, then verb, then defaults
    • Specify a leading "=" to search only the exact device/modifier/verb specified, and not search through each object in turn.
    • Examples:
      • "PlaybackPCM/Play Music"
      • "CapturePCM/SPDIF"
      • From ValueDefaults only: "=Variable"
      • From current active verb: "=Variable//"
      • From verb "Verb": "=Variable//Verb"
      • From "Modifier" in current active verb: "=Variable/Modifier/"
      • From "Modifier" in "Verb": "=Variable/Modifier/Verb"

Recommended names for values:

  • TQ
    • Tone Quality
  • PlaybackPCM
    • full PCM playback device name
  • PlaybackPCMIsDummy
    • Valid values: "yes" and "no". If set to "yes", the PCM named by the PlaybackPCM value is a dummy device, meaning that opening it enables an audio path in the hardware, but writing to the PCM device has no effect.
  • CapturePCM
    • full PCM capture device name
  • CapturePCMIsDummy
    • Valid values: "yes" and "no". If set to "yes", the PCM named by the CapturePCM value is a dummy device, meaning that opening it enables an audio path in the hardware, but reading from the PCM device has no effect.
  • PlaybackRate
    • playback device sample rate
  • PlaybackChannels
    • playback device channel count
  • PlaybackCTL
    • playback control device name
  • PlaybackVolume
    • playback control volume ID string
  • PlaybackSwitch
    • playback control switch ID string
  • CaptureRate
    • capture device sample rate
  • CaptureChannels
    • capture device channel count
  • CaptureCTL
    • capture control device name
  • CaptureVolume
    • capture control volume ID string
  • CaptureSwitch
    • capture control switch ID string
  • PlaybackMixer
    • name of playback mixer
  • PlaybackMixerID
    • mixer playback ID
  • CaptureMixer
    • name of capture mixer
  • CaptureMixerID
    • mixer capture ID
  • JackControl, JackDev, JackHWMute
    • Jack information for a device. The jack status can be reported via a kcontrol and/or via an input device. JackControl is the kcontrol name of the jack, and JackDev is the input device id of the jack (if the full input device path is /dev/input/by-id/foo, the JackDev value should be "foo"). UCM configuration files should contain both JackControl and JackDev when possible, because applications are likely to support only one or the other.

      If JackHWMute is set, it indicates that when the jack is plugged in, the hardware automatically mutes some other device(s). The JackHWMute value is a space-separated list of device names (this isn't compatible with device names with spaces in them, so don't use such device names!). Note that JackHWMute should be used only when the hardware enforces the automatic muting. If the hardware doesn't enforce any muting, it may still be tempting to set JackHWMute to trick upper software layers to e.g. automatically mute speakers when headphones are plugged in, but that's application policy configuration that doesn't belong to UCM configuration files.

Parameters:
uc_mgrUse case manager
identifier
valueValue pointer
Returns:
Zero if success, otherwise a negative error code

Note: String is dynamically allocated, use free() to deallocate this string.

int snd_use_case_get_list ( snd_use_case_mgr_t uc_mgr,
const char *  identifier,
const char **  list[] 
)

Obtain a list of entries.

Parameters:
uc_mgrUse case manager (may be NULL - card list)
identifier(may be NULL - card list)
listReturned allocated list
Returns:
Number of list entries if success, otherwise a negative error code

Defined identifiers:

  • NULL - get card list (in pair cardname+comment)
  • _verbs - get verb list (in pair verb+comment)
  • _devices[/{verb}] - get list of supported devices (in pair device+comment)
  • _modifiers[/{verb}] - get list of supported modifiers (in pair modifier+comment)
  • TQ[/{verb}] - get list of TQ identifiers
  • _enadevs - get list of enabled devices
  • _enamods - get list of enabled modifiers
  • _supporteddevs/{modifier}|{device}[/{verb}] - list of supported devices
  • _conflictingdevs/{modifier}|{device}[/{verb}] - list of conflicting devices

Note that at most one of the supported/conflicting devs lists has any entries, and when neither is present, all devices are supported.

Parameters:
uc_mgrUse case manager (may be NULL - card list)
identifier(may be NULL - card list)
listReturned allocated list
Returns:
Number of list entries if success, otherwise a negative error code
int snd_use_case_geti ( snd_use_case_mgr_t uc_mgr,
const char *  identifier,
long *  value 
)

Get current - integer.

Parameters:
uc_mgrUse case manager
identifier
valueresult
Returns:
Zero if success, otherwise a negative error code

Known identifiers:

  • _devstatus/{device} - return status for given device
  • _modstatus/{modifier} - return status for given modifier
Parameters:
uc_mgrUse case manager
identifier
Returns:
Value if success, otherwise a negative error code
char* snd_use_case_identifier ( const char *  fmt,
  ... 
)

Create an identifier.

Parameters:
fmtFormat (sprintf like)
...Optional arguments for sprintf like format
Returns:
Allocated string identifier or NULL on error
int snd_use_case_mgr_close ( snd_use_case_mgr_t uc_mgr)

Close use case manager.

Parameters:
uc_mgrUse case manager
Returns:
zero if success, otherwise a negative error code
Parameters:
uc_mgrUse case manager
Returns:
zero on success, otherwise a negative error code
int snd_use_case_mgr_open ( snd_use_case_mgr_t **  uc_mgr,
const char *  card_name 
)

Open and initialise use case core for sound card.

Parameters:
uc_mgrReturned use case manager pointer
card_nameSound card name.
Returns:
zero if success, otherwise a negative error code

Open and initialise use case core for sound card.

Parameters:
uc_mgrReturned use case manager pointer
card_namename of card to open
Returns:
zero on success, otherwise a negative error code
int snd_use_case_mgr_reload ( snd_use_case_mgr_t uc_mgr)

Reload and re-parse use case configuration files for sound card.

Parameters:
uc_mgrUse case manager
Returns:
zero if success, otherwise a negative error code

Reload and re-parse use case configuration files for sound card.

Parameters:
uc_mgrUse case manager
Returns:
zero on success, otherwise a negative error code
int snd_use_case_mgr_reset ( snd_use_case_mgr_t uc_mgr)

Reset use case manager verb, device, modifier to deafult settings.

Parameters:
uc_mgrUse case manager
Returns:
zero if success, otherwise a negative error code

Reset use case manager verb, device, modifier to deafult settings.

Parameters:
uc_mgrUse case manager
Returns:
zero on success, otherwise a negative error code
int snd_use_case_set ( snd_use_case_mgr_t uc_mgr,
const char *  identifier,
const char *  value 
)

Set new.

Parameters:
uc_mgrUse case manager
identifier
valueValue
Returns:
Zero if success, otherwise a negative error code

Known identifiers:

  • _verb - set current verb = value
  • _enadev - enable given device = value
  • _disdev - disable given device = value
  • _swdev/{old_device} - new_device = value
    • disable old_device and then enable new_device
    • if old_device is not enabled just return
    • check transmit sequence firstly
  • _enamod - enable given modifier = value
  • _dismod - disable given modifier = value
  • _swmod/{old_modifier} - new_modifier = value
    • disable old_modifier and then enable new_modifier
    • if old_modifier is not enabled just return
    • check transmit sequence firstly
Parameters:
uc_mgrUse case manager
identifier
valueValue
Returns:
Zero if success, otherwise a negative error code