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webm.go
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webm.go
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package elements
import (
"sync"
"github.com/at-wat/ebml-go/mkvcore"
"github.com/at-wat/ebml-go/webm"
avp "github.com/pion/ion-avp/pkg"
"github.com/pion/ion-avp/pkg/log"
)
const (
// IDWebmSaver .
IDWebmSaver = "WebmSaver"
)
// WebmSaverConfig .
type WebmSaverConfig struct {
ID string
}
// WebmSaver Module for saving rtp streams to webm
type WebmSaver struct {
sync.Mutex
id string
closed bool
audioWriter, videoWriter webm.BlockWriteCloser
audioTimestamp, videoTimestamp uint32
sampleWriter *SampleWriter
}
// NewWebmSaver Initialize a new webm saver
func NewWebmSaver(config WebmSaverConfig) *WebmSaver {
return &WebmSaver{
id: config.ID,
sampleWriter: NewSampleWriter(),
}
}
// ID of element
func (s *WebmSaver) ID() string {
return IDWebmSaver
}
// Write sample to webmsaver
func (s *WebmSaver) Write(sample *avp.Sample) error {
if sample.Type == avp.TypeVP8 {
s.pushVP8(sample)
} else if sample.Type == avp.TypeOpus {
s.pushOpus(sample)
}
return nil
}
// Attach attach a child element
func (s *WebmSaver) Attach(e avp.Element) error {
return s.sampleWriter.Attach(e)
}
// Close Close the WebmSaver
func (s *WebmSaver) Close() {
s.Lock()
defer s.Unlock()
log.Infof("WebmSaver.Close() => %s", s.id)
if s.closed {
return
}
s.closed = true
if s.audioWriter != nil {
if err := s.audioWriter.Close(); err != nil {
log.Errorf("audio close err: %s", err)
}
}
if s.videoWriter != nil {
if err := s.videoWriter.Close(); err != nil {
log.Errorf("video close err: %s", err)
}
}
}
func (s *WebmSaver) pushOpus(sample *avp.Sample) {
if s.audioWriter != nil {
if s.audioTimestamp == 0 {
s.audioTimestamp = sample.Timestamp
}
t := (sample.Timestamp - s.audioTimestamp) / 48
if _, err := s.audioWriter.Write(true, int64(t), sample.Payload.([]byte)); err != nil {
log.Errorf("audio writer err: %s", err)
}
}
}
func (s *WebmSaver) pushVP8(sample *avp.Sample) {
payload := sample.Payload.([]byte)
// Read VP8 header.
videoKeyframe := (payload[0]&0x1 == 0)
if videoKeyframe {
// Keyframe has frame information.
raw := uint(payload[6]) | uint(payload[7])<<8 | uint(payload[8])<<16 | uint(payload[9])<<24
width := int(raw & 0x3FFF)
height := int((raw >> 16) & 0x3FFF)
if s.videoWriter == nil || s.audioWriter == nil {
// Initialize WebM saver using received frame size.
s.initWriter(width, height)
}
}
if s.videoWriter != nil {
if s.videoTimestamp == 0 {
s.videoTimestamp = sample.Timestamp
}
t := (sample.Timestamp - s.videoTimestamp) / 90
if _, err := s.videoWriter.Write(videoKeyframe, int64(t), payload); err != nil {
log.Errorf("video write err: %s", err)
}
}
}
func (s *WebmSaver) initWriter(width, height int) {
ws, err := webm.NewSimpleBlockWriter(s.sampleWriter,
[]webm.TrackEntry{
{
Name: "Audio",
TrackNumber: 1,
TrackUID: 12345,
CodecID: "A_OPUS",
TrackType: 2,
DefaultDuration: 20000000,
Audio: &webm.Audio{
SamplingFrequency: 48000.0,
Channels: 2,
},
}, {
Name: "Video",
TrackNumber: 2,
TrackUID: 67890,
CodecID: "V_VP8",
TrackType: 1,
DefaultDuration: 20000000,
Video: &webm.Video{
PixelWidth: uint64(width),
PixelHeight: uint64(height),
},
},
}, mkvcore.WithSeekHead(true))
if err != nil {
log.Errorf("init writer err: %s", err)
}
log.Infof("WebM saver has started with video width=%d, height=%d\n", width, height)
s.audioWriter = ws[0]
s.videoWriter = ws[1]
}
// SampleWriter for writing samples
type SampleWriter struct {
children map[string]avp.Element
}
// NewSampleWriter creates a new sample writer
func NewSampleWriter() *SampleWriter {
return &SampleWriter{
children: make(map[string]avp.Element),
}
}
// Attach a child element
func (w *SampleWriter) Attach(e avp.Element) error {
if w.children[e.ID()] == nil {
log.Infof("Transcribe.Attach element => %s", e.ID())
w.children[e.ID()] = e
return nil
}
return ErrElementAlreadyAttached
}
// Write sample
func (w *SampleWriter) Write(p []byte) (n int, err error) {
for _, e := range w.children {
sample := &avp.Sample{
Type: TypeBinary,
Payload: p,
}
err := e.Write(sample)
if err != nil {
log.Errorf("SampleWriter.Write error => %s", err)
}
}
return len(p), nil
}
// Close writer
func (w *SampleWriter) Close() error {
for _, e := range w.children {
e.Close()
}
return nil
}