mediamtx/internal/hls/muxer_variant_fmp4_segmenter.go

401 lines
8.9 KiB
Go

package hls
import (
"fmt"
"time"
"github.com/aler9/gortsplib/v2/pkg/codecs/h264"
"github.com/aler9/gortsplib/v2/pkg/codecs/h265"
"github.com/aler9/gortsplib/v2/pkg/format"
"github.com/aler9/rtsp-simple-server/internal/hls/fmp4"
)
func partDurationIsCompatible(partDuration time.Duration, sampleDuration time.Duration) bool {
if sampleDuration > partDuration {
return false
}
f := (partDuration / sampleDuration)
if (partDuration % sampleDuration) != 0 {
f++
}
f *= sampleDuration
return partDuration > ((f * 85) / 100)
}
func findCompatiblePartDuration(
minPartDuration time.Duration,
sampleDurations map[time.Duration]struct{},
) time.Duration {
i := minPartDuration
for ; i < 5*time.Second; i += 5 * time.Millisecond {
isCompatible := func() bool {
for sd := range sampleDurations {
if !partDurationIsCompatible(i, sd) {
return false
}
}
return true
}()
if isCompatible {
break
}
}
return i
}
type dtsExtractor interface {
Extract([][]byte, time.Duration) (time.Duration, error)
}
func allocateDTSExtractor(track format.Format) dtsExtractor {
switch track.(type) {
case *format.H264:
return h264.NewDTSExtractor()
case *format.H265:
return h265.NewDTSExtractor()
}
return nil
}
type augmentedVideoSample struct {
fmp4.PartSample
dts time.Duration
ntp time.Time
}
type augmentedAudioSample struct {
fmp4.PartSample
dts time.Duration
ntp time.Time
}
type muxerVariantFMP4Segmenter struct {
lowLatency bool
segmentDuration time.Duration
partDuration time.Duration
segmentMaxSize uint64
videoTrack format.Format
audioTrack format.Format
onSegmentFinalized func(*muxerVariantFMP4Segment)
onPartFinalized func(*muxerVariantFMP4Part)
startDTS time.Duration
videoFirstRandomAccessReceived bool
videoDTSExtractor dtsExtractor
lastVideoParams [][]byte
currentSegment *muxerVariantFMP4Segment
nextSegmentID uint64
nextPartID uint64
nextVideoSample *augmentedVideoSample
nextAudioSample *augmentedAudioSample
firstSegmentFinalized bool
sampleDurations map[time.Duration]struct{}
adjustedPartDuration time.Duration
}
func newMuxerVariantFMP4Segmenter(
lowLatency bool,
segmentCount int,
segmentDuration time.Duration,
partDuration time.Duration,
segmentMaxSize uint64,
videoTrack format.Format,
audioTrack format.Format,
onSegmentFinalized func(*muxerVariantFMP4Segment),
onPartFinalized func(*muxerVariantFMP4Part),
) *muxerVariantFMP4Segmenter {
m := &muxerVariantFMP4Segmenter{
lowLatency: lowLatency,
segmentDuration: segmentDuration,
partDuration: partDuration,
segmentMaxSize: segmentMaxSize,
videoTrack: videoTrack,
audioTrack: audioTrack,
onSegmentFinalized: onSegmentFinalized,
onPartFinalized: onPartFinalized,
sampleDurations: make(map[time.Duration]struct{}),
}
// add initial gaps, required by iOS LL-HLS
if m.lowLatency {
m.nextSegmentID = 7
}
return m
}
func (m *muxerVariantFMP4Segmenter) genSegmentID() uint64 {
id := m.nextSegmentID
m.nextSegmentID++
return id
}
func (m *muxerVariantFMP4Segmenter) genPartID() uint64 {
id := m.nextPartID
m.nextPartID++
return id
}
// iPhone iOS fails if part durations are less than 85% of maximum part duration.
// find a part duration that is compatible with all received sample durations
func (m *muxerVariantFMP4Segmenter) adjustPartDuration(du time.Duration) {
if !m.lowLatency || m.firstSegmentFinalized {
return
}
if _, ok := m.sampleDurations[du]; !ok {
m.sampleDurations[du] = struct{}{}
m.adjustedPartDuration = findCompatiblePartDuration(
m.partDuration,
m.sampleDurations,
)
}
}
func (m *muxerVariantFMP4Segmenter) writeH26x(ntp time.Time, pts time.Duration, au [][]byte) error {
randomAccessPresent := false
switch m.videoTrack.(type) {
case *format.H264:
nonIDRPresent := false
for _, nalu := range au {
typ := h264.NALUType(nalu[0] & 0x1F)
switch typ {
case h264.NALUTypeIDR:
randomAccessPresent = true
case h264.NALUTypeNonIDR:
nonIDRPresent = true
}
}
if !randomAccessPresent && !nonIDRPresent {
return nil
}
case *format.H265:
for _, nalu := range au {
typ := h265.NALUType((nalu[0] >> 1) & 0b111111)
switch typ {
case h265.NALUType_IDR_W_RADL, h265.NALUType_IDR_N_LP, h265.NALUType_CRA_NUT:
randomAccessPresent = true
}
}
}
return m.writeH26xEntry(ntp, pts, au, randomAccessPresent)
}
func (m *muxerVariantFMP4Segmenter) writeH26xEntry(
ntp time.Time,
pts time.Duration,
au [][]byte,
randomAccessPresent bool,
) error {
var dts time.Duration
if !m.videoFirstRandomAccessReceived {
// skip sample silently until we find one with an IDR
if !randomAccessPresent {
return nil
}
m.videoFirstRandomAccessReceived = true
m.videoDTSExtractor = allocateDTSExtractor(m.videoTrack)
m.lastVideoParams = extractVideoParams(m.videoTrack)
var err error
dts, err = m.videoDTSExtractor.Extract(au, pts)
if err != nil {
return fmt.Errorf("unable to extract DTS: %v", err)
}
m.startDTS = dts
dts = 0
pts -= m.startDTS
} else {
var err error
dts, err = m.videoDTSExtractor.Extract(au, pts)
if err != nil {
return fmt.Errorf("unable to extract DTS: %v", err)
}
dts -= m.startDTS
pts -= m.startDTS
}
avcc, err := h264.AVCCMarshal(au)
if err != nil {
return err
}
sample := &augmentedVideoSample{
PartSample: fmp4.PartSample{
PTSOffset: int32(durationGoToMp4(pts-dts, 90000)),
IsNonSyncSample: !randomAccessPresent,
Payload: avcc,
},
dts: dts,
ntp: ntp,
}
// put samples into a queue in order to
// - compute sample duration
// - check if next sample is IDR
sample, m.nextVideoSample = m.nextVideoSample, sample
if sample == nil {
return nil
}
sample.Duration = uint32(durationGoToMp4(m.nextVideoSample.dts-sample.dts, 90000))
if m.currentSegment == nil {
// create first segment
m.currentSegment = newMuxerVariantFMP4Segment(
m.lowLatency,
m.genSegmentID(),
sample.ntp,
sample.dts,
m.segmentMaxSize,
m.videoTrack,
m.audioTrack,
m.genPartID,
m.onPartFinalized,
)
}
m.adjustPartDuration(durationMp4ToGo(uint64(sample.Duration), 90000))
err = m.currentSegment.writeH264(sample, m.adjustedPartDuration)
if err != nil {
return err
}
// switch segment
if randomAccessPresent {
videoParams := extractVideoParams(m.videoTrack)
paramsChanged := !videoParamsEqual(m.lastVideoParams, videoParams)
if (m.nextVideoSample.dts-m.currentSegment.startDTS) >= m.segmentDuration ||
paramsChanged {
err := m.currentSegment.finalize(m.nextVideoSample.dts)
if err != nil {
return err
}
m.onSegmentFinalized(m.currentSegment)
m.firstSegmentFinalized = true
m.currentSegment = newMuxerVariantFMP4Segment(
m.lowLatency,
m.genSegmentID(),
m.nextVideoSample.ntp,
m.nextVideoSample.dts,
m.segmentMaxSize,
m.videoTrack,
m.audioTrack,
m.genPartID,
m.onPartFinalized,
)
if paramsChanged {
m.lastVideoParams = videoParams
m.firstSegmentFinalized = false
// reset adjusted part duration
m.sampleDurations = make(map[time.Duration]struct{})
}
}
}
return nil
}
func (m *muxerVariantFMP4Segmenter) writeAudio(ntp time.Time, dts time.Duration, au []byte) error {
if m.videoTrack != nil {
// wait for the video track
if !m.videoFirstRandomAccessReceived {
return nil
}
dts -= m.startDTS
if dts < 0 {
return nil
}
}
sample := &augmentedAudioSample{
PartSample: fmp4.PartSample{
Payload: au,
},
dts: dts,
ntp: ntp,
}
// put samples into a queue in order to compute the sample duration
sample, m.nextAudioSample = m.nextAudioSample, sample
if sample == nil {
return nil
}
sample.Duration = uint32(durationGoToMp4(m.nextAudioSample.dts-sample.dts, uint32(m.audioTrack.ClockRate())))
if m.videoTrack == nil {
if m.currentSegment == nil {
// create first segment
m.currentSegment = newMuxerVariantFMP4Segment(
m.lowLatency,
m.genSegmentID(),
sample.ntp,
sample.dts,
m.segmentMaxSize,
m.videoTrack,
m.audioTrack,
m.genPartID,
m.onPartFinalized,
)
}
} else {
// wait for the video track
if m.currentSegment == nil {
return nil
}
}
err := m.currentSegment.writeAudio(sample, m.partDuration)
if err != nil {
return err
}
// switch segment
if m.videoTrack == nil &&
(m.nextAudioSample.dts-m.currentSegment.startDTS) >= m.segmentDuration {
err := m.currentSegment.finalize(0)
if err != nil {
return err
}
m.onSegmentFinalized(m.currentSegment)
m.firstSegmentFinalized = true
m.currentSegment = newMuxerVariantFMP4Segment(
m.lowLatency,
m.genSegmentID(),
m.nextAudioSample.ntp,
m.nextAudioSample.dts,
m.segmentMaxSize,
m.videoTrack,
m.audioTrack,
m.genPartID,
m.onPartFinalized,
)
}
return nil
}