80 lines
1.7 KiB
Go
80 lines
1.7 KiB
Go
//go:build overlord_webrtc
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package webrtcpub
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import (
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"sync"
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"time"
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"github.com/pion/webrtc/v4"
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"github.com/pion/webrtc/v4/pkg/media"
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"github.com/thesyncim/gopus"
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)
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const (
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opusInputRate = 48000
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opusChannels = 2
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opusPacketMs = 20
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opusSamplesPerFrame = opusInputRate * opusPacketMs / 1000
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opusBitrate = 96000
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)
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type opusAudioWriter struct {
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t *webrtc.TrackLocalStaticSample
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encoder *gopus.Encoder
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mu sync.Mutex
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pcm []int16
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packet []byte
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}
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func newOpusAudioWriter(t *webrtc.TrackLocalStaticSample) (*opusAudioWriter, error) {
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encoder, err := gopus.NewEncoder(gopus.EncoderConfig{
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SampleRate: opusInputRate,
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Channels: opusChannels,
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Application: gopus.ApplicationAudio,
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})
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if err != nil {
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return nil, err
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}
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if err := encoder.SetBitrate(opusBitrate); err != nil {
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return nil, err
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}
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if err := encoder.SetInBandFEC(gopus.InBandFECEnabled); err != nil {
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return nil, err
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}
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return &opusAudioWriter{
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t: t,
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encoder: encoder,
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pcm: make([]int16, 0, opusSamplesPerFrame*4),
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packet: make([]byte, 4000),
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}, nil
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}
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func (w *opusAudioWriter) WriteAudio(pcm []int16) error {
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if len(pcm) == 0 {
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return nil
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}
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w.mu.Lock()
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defer w.mu.Unlock()
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w.pcm = append(w.pcm, pcm...)
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frameValues := opusSamplesPerFrame * opusChannels
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for len(w.pcm) >= frameValues {
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n, err := w.encoder.EncodeInt16(w.pcm[:frameValues], w.packet)
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if err != nil {
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w.pcm = w.pcm[:0]
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return err
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}
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if n > 0 {
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if err := w.t.WriteSample(media.Sample{
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Data: w.packet[:n],
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Duration: opusPacketMs * time.Millisecond,
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}); err != nil {
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w.pcm = w.pcm[:0]
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return err
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}
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}
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w.pcm = w.pcm[frameValues:]
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}
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return nil
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}
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