Capability: Microphone

[danicic]

Capability Microphone

A capability for an Internet Protocol microphone or an IP microphone.

Properties

Name	Description	Input	Output
OutputPayloadType	Type of the payload output (e.g., stream or buffer/batch).	OutputPayloadData	OutputPayloadData
BitDepth	The number of bits of information in each sample. It is the resolution of each sample, e.g. 8, 16 or 24 bits per sample.	BitDepthData	BitDepthData	`
Encoding	The number that represents the amplitude of the signal at a specific point in time, e.g., an (un-)signed integer or a floating point	EncodingData	EncodingData	`
NumberOfChannels	The number of channels used, e.g. mono uses 1 channel and stereo uses 2 channels.	ChannelData	ChannelData	`
Rate	Recording rate.	RateData	RateData	`
SilenceTimeout	The silence is detected after reaching a number of consecutive frames defined by the SilenceTimeout.	SilenceTimeoutData	SilenceTimeoutData	`
SilenceStop	Stop recording on silence.	SilenceStopData	SilenceStopData	`

Provide Input for writable properties.

Actions

Name	Description	Input	Output
TurnOn	Turn on a thing (microphone).	---	---
TurnOff	Turn off a thing (microphone).	---	---
StartRecording	Starts recording activity (e.g., audio, video).	---	Stream or Buffer Data
StopRecording	Stops recording activity (e.g., audio, video).	---	---
PauseRecording	Pause recording activity (e.g., audio, video).	---	---
ResumeRecording	Resume recording activity (e.g., audio, video).	---	Stream or Buffer Data

Data Types

Numeric Data Types:

Name	Definition	Min Value	Max Value	Unit Code
BitDepthData	Number	4	64	---
EncodingData	Number (Integer, SignedInteger, Float)	---	---	---
RateData	Number	---	---	---
SilenceTimeoutData	Number	---	---	Second or number of frames

Enumeration or Text Data Types:

Name	Data Type	Enumeration (comma separated) Values
OutputPayloadData	String	Stream, Buffer
ChannelData	Number	1, 2

Boolean Data Types:

Name
SilenceStopData

[danicic]

Properties such as for example: OutputPayloadType, Rate, BitDepth, SilenceTimeout etc. (see above) are configuration parameters rather than properties in sense of W3C TD Properties. Some configuration parameters are supposed to be set before a Thing can be used. Others can be initialized but later changed. Some of them are mandatory, wheres the other may be optional and so forth. Thus, we should extend the iotschema model to accommodate configuration parameters, and also to propose this extension to W3C WoT Thing Description model.

[6d77]

Comment on the naming: technically, a Microphone is a device which converts air vibrations into an electrical signal without recording. A recording device is separated from that. There should be a better naming taking into account the technical realizations and also the possibilities to combine optical and acoustical sensing and recording. Just consider the following technically distinct components with the described functions (capabilities?):

• a microphone typically with an analog signal output
• an imaging sensor typically outputting raw image data
• some kind of audio signal converter producing digital samples of the analog signal and possibly encoding and/or compressing it using some algorithm like G.711 or MP3
• some kind of image processor doing image preprocessing and compression, e.g. to JPEG for still images or using some of the video codecs for moving images
• a recorder storing the converted audio and/or video on a storage device

Actual devices may combine any of those:

• A camera may just do the sensing and preprocessing and then sending the signal to somewhere else. An example is a studio TV camera.
• It may however also include a microphone, the audio converter and the recording part in a single device. An example is a typical consumer video camera or even a mobile phone.
• Microphones are often separate devices, e.g. as studio microphones or as part of a headset.

For the naming I propose to think into the following direction:

Nouns are quite often not good candidates to describe a capability. IMHO they tend to describe things and devices, like a microphone. Instead a -ing form describing a process much more relates to a capability, e.g.

• AudioSensing
• ImageSensing
• AudioEncoding
• VideoEncoding
• AudioVideoRecording

@danicic what do you think?