mirror of https://bitbucket.org/ausocean/av.git
326 lines
9.0 KiB
Go
326 lines
9.0 KiB
Go
package revid
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import (
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"errors"
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"fmt"
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"io"
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"sync"
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"time"
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"github.com/yobert/alsa"
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"bitbucket.org/ausocean/av/codec/pcm"
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"bitbucket.org/ausocean/iot/pi/smartlogger"
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"bitbucket.org/ausocean/utils/logger"
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"bitbucket.org/ausocean/utils/ring"
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)
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const (
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logPath = "/var/log/netsender"
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rbDuration = 300 // seconds
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rbTimeout = 100 * time.Millisecond
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rbNextTimeout = 100 * time.Millisecond
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)
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var log *logger.Logger
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// AudioInput holds everything we need to know about the audio input stream.
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// NB: At 44100 Hz frame rate, 2 channels and 16-bit samples, a period of 5 seconds
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// results in PCM data chunks of 882000 bytes! A longer period exceeds datastore's 1MB blob limit.
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type AudioInput struct {
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mu sync.Mutex // mu protects the AudioInput.
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mode string // operating mode, either "Normal" or "Paused"
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source string // name of audio source, or empty for the default source
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dev *alsa.Device // audio input device
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ab alsa.Buffer // ALSA's buffer
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rb *ring.Buffer // our buffer
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chunkSize int
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vs int // our "var sum" to track var changes
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*AudioConfig
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}
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// AudioConfig provides parameters used by AudioInput.
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type AudioConfig struct {
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SampleRate int
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Channels int
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BitDepth int
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RecPeriod int
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Codec uint8
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}
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// NewAudioInput starts recording audio and returns an AudioInput struct which the audio can be read from.
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func NewAudioInput(cfg *AudioConfig) *AudioInput {
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logLevel := int(logger.Debug)
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validLogLevel := true
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if logLevel < int(logger.Debug) || logLevel > int(logger.Fatal) {
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logLevel = int(logger.Info)
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validLogLevel = false
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}
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logSender := smartlogger.New(logPath)
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log = logger.New(int8(logLevel), &logSender.LogRoller)
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log.Log(logger.Info, "log-netsender: Logger Initialized")
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if !validLogLevel {
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log.Log(logger.Error, "Invalid log level was defaulted to Info")
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}
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a := &AudioInput{}
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a.AudioConfig = cfg
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// Open the requested audio device.
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err := a.open()
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if err != nil {
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log.Log(logger.Fatal, "alsa.open failed", "error", err.Error())
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}
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// Capture audio in periods of a.RecPeriod seconds, and buffer rbDuration seconds in total.
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a.ab = a.dev.NewBufferDuration(time.Second * time.Duration(a.RecPeriod))
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a.chunkSize = (((len(a.ab.Data) / a.dev.BufferFormat().Channels) * a.Channels) / a.dev.BufferFormat().Rate) * a.SampleRate
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rbLen := rbDuration / a.RecPeriod
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a.rb = ring.NewBuffer(rbLen, a.chunkSize, rbTimeout)
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go a.input()
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return a
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}
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func (a *AudioInput) ChunkSize() int {
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return a.chunkSize
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}
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// open or re-open the recording device with the given name and prepare it to record.
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// If name is empty, the first recording device is used.
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func (a *AudioInput) open() error {
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if a.dev != nil {
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log.Log(logger.Debug, "Closing", "source", a.source)
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a.dev.Close()
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a.dev = nil
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}
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log.Log(logger.Debug, "Opening", "source", a.source)
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cards, err := alsa.OpenCards()
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if err != nil {
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return err
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}
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defer alsa.CloseCards(cards)
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for _, card := range cards {
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devices, err := card.Devices()
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if err != nil {
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return err
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}
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for _, dev := range devices {
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if dev.Type != alsa.PCM || !dev.Record {
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continue
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}
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if dev.Title == a.source || a.source == "" {
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a.dev = dev
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break
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}
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}
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}
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if a.dev == nil {
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return errors.New("No audio source found")
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}
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log.Log(logger.Debug, "Found audio source", "source", a.dev.Title)
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// ToDo: time out if Open takes too long.
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err = a.dev.Open()
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if err != nil {
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return err
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}
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log.Log(logger.Debug, "Opened audio source")
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// 2 channels is what most devices need to record in. If mono is requested,
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// the recording will be converted in formatBuffer().
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_, err = a.dev.NegotiateChannels(2)
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if err != nil {
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return err
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}
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// Try to negotiate a rate to record in that is divisible by the wanted rate
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// so that it can be easily downsampled to the wanted rate.
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// Note: if a card thinks it can record at a rate but can't actually, this can cause a failure. Eg.
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// the audioinjector is supposed to record at 8000Hz and 16000Hz but it can't due to a firmware issue,
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// to fix this 8000 and 16000 must be removed from this slice.
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rates := [8]int{8000, 16000, 32000, 44100, 48000, 88200, 96000, 192000}
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foundRate := false
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for i := 0; i < len(rates) && !foundRate; i++ {
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if rates[i] < a.SampleRate {
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continue
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}
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if rates[i]%a.SampleRate == 0 {
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_, err = a.dev.NegotiateRate(rates[i])
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if err == nil {
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foundRate = true
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log.Log(logger.Debug, "Sample rate set", "rate", rates[i])
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}
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}
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}
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// If no easily divisible rate is found, then use the default rate.
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if !foundRate {
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log.Log(logger.Warning, "Unable to sample at requested rate, default used.", "rateRequested", a.SampleRate)
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_, err = a.dev.NegotiateRate(defaultSampleRate)
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if err != nil {
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return err
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}
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log.Log(logger.Debug, "Sample rate set", "rate", defaultSampleRate)
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}
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var fmt alsa.FormatType
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switch a.BitDepth {
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case 16:
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fmt = alsa.S16_LE
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case 32:
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fmt = alsa.S32_LE
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default:
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return errors.New("Unsupported sample bits")
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}
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_, err = a.dev.NegotiateFormat(fmt)
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if err != nil {
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return err
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}
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// Either 8192 or 16384 bytes is a reasonable ALSA buffer size.
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_, err = a.dev.NegotiateBufferSize(8192, 16384)
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if err != nil {
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return err
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}
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if err = a.dev.Prepare(); err != nil {
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return err
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}
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log.Log(logger.Debug, "Successfully negotiated ALSA params")
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return nil
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}
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// input continously records audio and writes it to the ringbuffer.
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// Re-opens the device and tries again if ASLA returns an error.
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// Spends a lot of time sleeping in Paused mode.
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// ToDo: Currently, reading audio and writing to the ringbuffer are synchronous.
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// Need a way to asynchronously read from the ALSA buffer, i.e., _while_ it is recording to avoid any gaps.
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func (a *AudioInput) input() {
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for {
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a.mu.Lock()
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mode := a.mode
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a.mu.Unlock()
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if mode == "Paused" {
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time.Sleep(time.Duration(a.RecPeriod) * time.Second)
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continue
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}
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log.Log(logger.Debug, "Recording audio for period", "seconds", a.RecPeriod)
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a.mu.Lock()
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err := a.dev.Read(a.ab.Data)
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a.mu.Unlock()
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if err != nil {
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log.Log(logger.Debug, "Device.Read failed", "error", err.Error())
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a.mu.Lock()
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err = a.open() // re-open
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if err != nil {
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log.Log(logger.Fatal, "alsa.open failed", "error", err.Error())
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}
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a.mu.Unlock()
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continue
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}
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toWrite := a.formatBuffer()
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log.Log(logger.Debug, "Audio format conversion has been performed where needed")
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fmt.Printf("Writing %v bytes to ringbuffer\n", len(toWrite.Data))
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var n int
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n, err = a.rb.Write(toWrite.Data)
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fmt.Printf("Wrote %v bytes to ringbuffer\n", n)
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switch err {
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case nil:
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log.Log(logger.Debug, "Wrote audio to ringbuffer", "length", n)
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case ring.ErrDropped:
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log.Log(logger.Warning, "Dropped audio")
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default:
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log.Log(logger.Error, "Unexpected ringbuffer error", "error", err.Error())
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return
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}
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}
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}
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// read reads a full PCM chunk from the ringbuffer, returning the number of bytes read upon success.
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// Any errors returned are unexpected and should be considered fatal.
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func (a AudioInput) Read(p []byte) (n int, err error) {
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fmt.Println("Performing AudioInput read...")
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chunk, err := a.rb.Next(rbNextTimeout)
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switch err {
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case nil:
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// Do nothing.
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case ring.ErrTimeout:
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return 0, nil
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case io.EOF:
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log.Log(logger.Error, "Unexpected EOF from ring.Next")
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return 0, io.ErrUnexpectedEOF
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default:
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log.Log(logger.Error, "Unexpected error from ring.Next", "error", err.Error())
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return 0, err
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}
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fmt.Printf("Reading %v bytes from ringbuffer\n", chunk.Len())
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n, err = io.ReadFull(a.rb, p[:chunk.Len()])
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fmt.Printf("Read %v bytes from ringbuffer\n", n)
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if err != nil {
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log.Log(logger.Error, "Unexpected error from ring.Read", "error", err.Error())
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return n, err
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}
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log.Log(logger.Debug, "Read audio from ringbuffer", "length", n)
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return n, nil
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}
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// formatBuffer returns an ALSA buffer that has the recording data from the ac's original ALSA buffer but stored
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// in the desired format specified by the ac's parameters.
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func (a *AudioInput) formatBuffer() alsa.Buffer {
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var err error
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a.mu.Lock()
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wantChannels := a.Channels
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wantRate := a.SampleRate
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a.mu.Unlock()
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// If nothing needs to be changed, return the original.
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if a.ab.Format.Channels == wantChannels && a.ab.Format.Rate == wantRate {
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return a.ab
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}
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formatted := alsa.Buffer{Format: a.ab.Format}
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bufCopied := false
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if a.ab.Format.Channels != wantChannels {
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// Convert channels.
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if a.ab.Format.Channels == 2 && wantChannels == 1 {
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if formatted.Data, err = pcm.StereoToMono(a.ab); err != nil {
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log.Log(logger.Warning, "Channel conversion failed, audio has remained stereo", "error", err.Error())
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} else {
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formatted.Format.Channels = 1
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}
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bufCopied = true
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}
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}
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if a.ab.Format.Rate != wantRate {
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// Convert rate.
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if bufCopied {
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formatted.Data, err = pcm.Resample(formatted, wantRate)
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} else {
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formatted.Data, err = pcm.Resample(a.ab, wantRate)
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}
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if err != nil {
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log.Log(logger.Warning, "Rate conversion failed, audio has remained original rate", "error", err.Error())
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} else {
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formatted.Format.Rate = wantRate
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}
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}
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return formatted
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}
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