Voder

Voice things.

Crates to try:

• hound

  • Encoder/decoder
  • Very mature (3.4.0)

• cpal

  • Hardware audio out, low level
  • Tons of downloads!

• wavy

  • Microphone in, speaker out
  • ALSA

• sample

  • convert between floats, u8s, u16s, etc. via a trait
  • clip amplitude
  • scale playback
  • iterators
  • signal generators (sine, saw, noise, etc.)

• sonogram

  • generate spectrograms!
  • THEY LOOK SICK!

• audrey

  • supports range of audio encoders/decoders
  • flac, ogg, wav, alac

• waveform

  • generate images from wave files
  • con "it is probably threadsafe"

• samplerate

  • sample rate conversion

• riff-wave

  • read and write wav files
  • con: old (2016)

• wavefile

  • con: old (2016)
  • con: low on doc

• pitch

  • determine pitch and volume of samples
  • uses "bistream autocorrelation function (bcf)"
  • todo: also investigate BACF, uses peaks instead of zero-crossings

• libwave

  • wav library, based on nom zero-copy parser
  • PCM support
  • 18/16/32/64 bit support

Hardware

Enumerate hardware:

• pactl list short sinks

The linux headphone jack is named at startup:

• speaker-test -t wav -c 6 -D front

To change the 'default' speaker,

pactl list short sinks
pactl set-default-sink 'alsa_output.pci-0000_00_1f.3.analog-stereo'
speaker-test -t wav -c 6 -D default

This makes the rust code work on Desktop.

Links

• http://www.rossbencina.com/code/real-time-audio-programming-101-time-waits-for-nothing

Troubleshooting

THIS WORKS TO DEFEAT CHIPMUNK NOISES!

• https://bbs.archlinux.org/viewtopic.php?id=179923
  • https://wiki.archlinux.org/index.php/PulseAudio/Troubleshooting#Setting_the_default_fragment_number_and_buffer_size_in_PulseAudio

device.serial = "Focusrite_Scarlett_2i4_USB"
device.string = "surround40:1"
device.buffering.buffer_size = "1048576"
device.buffering.fragment_size = "524288"

PulseAudio's default sampling rate and bit depth are set to 44100Hz @ 16 bits.

1048576 / 1411200 (buffer size) 0.7430385487528345 = 743 ms 524288 / 1411200 (fragment size) 0.37151927437641724 = 372 ms