Files
go2rtc/pkg/mp4/demuxer.go
2025-04-04 19:58:05 +03:00

117 lines
2.3 KiB
Go

package mp4
import (
"github.com/AlexxIT/go2rtc/pkg/aac"
"github.com/AlexxIT/go2rtc/pkg/core"
"github.com/AlexxIT/go2rtc/pkg/h264"
"github.com/AlexxIT/go2rtc/pkg/iso"
"github.com/pion/rtp"
)
type Demuxer struct {
codecs map[uint32]*core.Codec
timeScales map[uint32]float32
}
func (d *Demuxer) Probe(init []byte) (medias []*core.Media) {
var trackID, timeScale uint32
if d.codecs == nil {
d.codecs = make(map[uint32]*core.Codec)
d.timeScales = make(map[uint32]float32)
}
atoms, _ := iso.DecodeAtoms(init)
for _, atom := range atoms {
var codec *core.Codec
switch atom := atom.(type) {
case *iso.AtomTkhd:
trackID = atom.TrackID
case *iso.AtomMdhd:
timeScale = atom.TimeScale
case *iso.AtomVideo:
switch atom.Name {
case "avc1":
codec = h264.ConfigToCodec(atom.Config)
}
case *iso.AtomAudio:
switch atom.Name {
case "mp4a":
codec = aac.ConfigToCodec(atom.Config)
}
}
if codec != nil {
d.codecs[trackID] = codec
d.timeScales[trackID] = float32(codec.ClockRate) / float32(timeScale)
medias = append(medias, &core.Media{
Kind: codec.Kind(),
Direction: core.DirectionRecvonly,
Codecs: []*core.Codec{codec},
})
}
}
return
}
func (d *Demuxer) GetTrackID(codec *core.Codec) uint32 {
for trackID, c := range d.codecs {
if c == codec {
return trackID
}
}
return 0
}
func (d *Demuxer) Demux(data2 []byte) (trackID uint32, packets []*core.Packet) {
atoms, err := iso.DecodeAtoms(data2)
if err != nil {
return 0, nil
}
var ts uint32
var trun *iso.AtomTrun
var data []byte
for _, atom := range atoms {
switch atom := atom.(type) {
case *iso.AtomTfhd:
trackID = atom.TrackID
case *iso.AtomTfdt:
ts = uint32(atom.DecodeTime)
case *iso.AtomTrun:
trun = atom
case *iso.AtomMdat:
data = atom.Data
}
}
timeScale := d.timeScales[trackID]
if timeScale == 0 {
return 0, nil
}
n := len(trun.SamplesDuration)
packets = make([]*core.Packet, n)
for i := 0; i < n; i++ {
duration := trun.SamplesDuration[i]
size := trun.SamplesSize[i]
// can be SPS, PPS and IFrame in one packet
timestamp := uint32(float32(ts) * timeScale)
packets[i] = &rtp.Packet{
Header: rtp.Header{Timestamp: timestamp},
Payload: data[:size],
}
data = data[size:]
ts += duration
}
return
}