microphone

This serves as the audio driver folder

Microphone Configuration

• microphone_model: currently only support RESPEAKER.

• chunk: number of frames per buffer from hardware to memory each time.

• record_seconds: number of seconds each time.

• channel_type

  • May be ASR (Audio Speech Recognition), RAW (Raw Audio Data) or Playback.

• sample_rate

  • Number of frames that are recorded per second.

• sample_width

  • Number of bytes per sample (1, 2, 3, or 4).

For example, if there are 6 channels with 16000 Hz rate and 2 bytes width, then 4 second recording is

• Number of frames: 16000

• Number of “samples”: 16000 * 6

  • I use the term “samples” here just to make it easy for understanding, which is seldom used in this context.

• Total size: 6 × 16,000 x 4 × 2 = 768,000 bytes.

You might see other metrics elsewhere as follows:

• BIT DEPTH same to sample_width except that the unit is bit.

• BIT RATE number of bits encoded per second (kbps or k) – for compressed format like mp3.

Output

• Raw microphone data (cyber channel apollo/sensor/microphone).