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refactor: only use trun.SampleCount() to get number of samples
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@tobbee
tobbee committed Oct 8, 2023
1 parent 2b80e1a commit 7cb73fb
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Showing 2 changed files with 24 additions and 27 deletions.
2 changes: 1 addition & 1 deletion mp4/fragment.go
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Original file line number Diff line number Diff line change
Expand Up @@ -422,7 +422,7 @@ func (f *Fragment) AddSampleInterval(sItvl SampleInterval) error {
moof := f.Moof
traf := moof.Traf
trun := traf.Trun
if trun.sampleCount == 0 {
if trun.SampleCount() == 0 {
traf.Tfdt.SetBaseMediaDecodeTime(sItvl.FirstDecodeTime)
}
trun.AddSamples(sItvl.Samples)
Expand Down
49 changes: 23 additions & 26 deletions mp4/trun.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,6 @@ import (
type TrunBox struct {
Version byte
Flags uint32
sampleCount uint32
DataOffset int32
firstSampleFlags uint32 // interpreted same way as SampleFlags
Samples []Sample
Expand All @@ -37,10 +36,9 @@ func DecodeTrun(hdr BoxHeader, startPos uint64, r io.Reader) (Box, error) {
versionAndFlags := s.ReadUint32()
sampleCount := s.ReadUint32()
t := &TrunBox{
Version: byte(versionAndFlags >> 24),
Flags: versionAndFlags & flagsMask,
sampleCount: sampleCount,
Samples: make([]Sample, sampleCount),
Version: byte(versionAndFlags >> 24),
Flags: versionAndFlags & flagsMask,
Samples: make([]Sample, 0, sampleCount),
}

if t.HasDataOffset() {
Expand All @@ -52,7 +50,7 @@ func DecodeTrun(hdr BoxHeader, startPos uint64, r io.Reader) (Box, error) {
}

var i uint32
for i = 0; i < t.sampleCount; i++ {
for i = 0; i < sampleCount; i++ {
var dur, size, flags uint32
var cto int32
if t.HasSampleDuration() {
Expand All @@ -69,7 +67,7 @@ func DecodeTrun(hdr BoxHeader, startPos uint64, r io.Reader) (Box, error) {
if t.HasSampleCompositionTimeOffset() {
cto = s.ReadInt32()
}
t.Samples[i] = Sample{flags, dur, size, cto}
t.Samples = append(t.Samples, Sample{flags, dur, size, cto})
}

return t, nil
Expand All @@ -80,10 +78,9 @@ func DecodeTrunSR(hdr BoxHeader, startPos uint64, sr bits.SliceReader) (Box, err
versionAndFlags := sr.ReadUint32()
sampleCount := sr.ReadUint32()
t := &TrunBox{
Version: byte(versionAndFlags >> 24),
Flags: versionAndFlags & flagsMask,
sampleCount: sampleCount,
Samples: make([]Sample, sampleCount),
Version: byte(versionAndFlags >> 24),
Flags: versionAndFlags & flagsMask,
Samples: make([]Sample, 0, sampleCount),
}

if t.HasDataOffset() {
Expand All @@ -95,7 +92,7 @@ func DecodeTrunSR(hdr BoxHeader, startPos uint64, sr bits.SliceReader) (Box, err
}

var i uint32
for i = 0; i < t.sampleCount; i++ {
for i = 0; i < sampleCount; i++ {
var dur, size, flags uint32
var cto int32
if t.HasSampleDuration() {
Expand All @@ -112,7 +109,7 @@ func DecodeTrunSR(hdr BoxHeader, startPos uint64, sr bits.SliceReader) (Box, err
if t.HasSampleCompositionTimeOffset() {
cto = sr.ReadInt32()
}
t.Samples[i] = Sample{flags, dur, size, cto}
t.Samples = append(t.Samples, Sample{flags, dur, size, cto})
}

return t, sr.AccError()
Expand All @@ -123,7 +120,6 @@ func CreateTrun(writeOrderNr uint32) *TrunBox {
trun := &TrunBox{
Version: 1, // Signed composition_time_offset
Flags: 0xf01, // Data offset and all sample data present
sampleCount: 0,
DataOffset: 0,
firstSampleFlags: 0,
Samples: nil,
Expand Down Expand Up @@ -157,7 +153,7 @@ func (t *TrunBox) AddSampleDefaultValues(tfhd *TfhdBox, trex *TrexBox) (totalDur
}
var i uint32
totalDur = 0
for i = 0; i < t.sampleCount; i++ {
for i = 0; i < t.SampleCount(); i++ {
if !t.HasSampleDuration() {
t.Samples[i].Dur = defaultSampleDuration
}
Expand Down Expand Up @@ -193,7 +189,7 @@ func (t *TrunBox) RemoveFirstSampleFlags() {

// SampleCount - return how many samples are defined
func (t *TrunBox) SampleCount() uint32 {
return t.sampleCount
return uint32(len(t.Samples))
}

// HasDataOffset - interpreted dataOffsetPresent flag
Expand Down Expand Up @@ -253,7 +249,7 @@ func (t *TrunBox) Size() uint64 {
if t.HasSampleCompositionTimeOffset() {
bytesPerSample += 4
}
sz += int(t.sampleCount) * bytesPerSample
sz += int(t.SampleCount()) * bytesPerSample
return uint64(sz)
}

Expand All @@ -276,7 +272,7 @@ func (t *TrunBox) EncodeSW(sw bits.SliceWriter) error {
}
versionAndFlags := (uint32(t.Version) << 24) + t.Flags
sw.WriteUint32(versionAndFlags)
sw.WriteUint32(t.sampleCount)
sw.WriteUint32(t.SampleCount())
if t.HasDataOffset() {
if t.DataOffset == 0 {
panic("trun data offset not set")
Expand All @@ -287,7 +283,7 @@ func (t *TrunBox) EncodeSW(sw bits.SliceWriter) error {
sw.WriteUint32(t.firstSampleFlags)
}
var i uint32
for i = 0; i < t.sampleCount; i++ {
for i = 0; i < t.SampleCount(); i++ {
if t.HasSampleDuration() {
sw.WriteUint32(t.Samples[i].Dur)
}
Expand All @@ -308,7 +304,7 @@ func (t *TrunBox) EncodeSW(sw bits.SliceWriter) error {
// Info - specificBoxLevels trun:1 gives details
func (t *TrunBox) Info(w io.Writer, specificBoxLevels, indent, indentStep string) error {
bd := newInfoDumper(w, indent, t, int(t.Version), t.Flags)
bd.write(" - sampleCount: %d", t.sampleCount)
bd.write(" - sampleCount: %d", t.SampleCount())
level := getInfoLevel(t, specificBoxLevels)
if level > 0 {
if t.HasDataOffset() {
Expand All @@ -317,7 +313,7 @@ func (t *TrunBox) Info(w io.Writer, specificBoxLevels, indent, indentStep string
if t.HasFirstSampleFlags() {
bd.write(" - firstSampleFlags: %08x (%s)", t.firstSampleFlags, DecodeSampleFlags(t.firstSampleFlags))
}
for i := 0; i < int(t.sampleCount); i++ {
for i := 0; i < int(t.SampleCount()); i++ {
msg := fmt.Sprintf(" - sample[%d]:", i+1)
if t.HasSampleDuration() {
msg += fmt.Sprintf(" dur=%d", t.Samples[i].Dur)
Expand Down Expand Up @@ -415,19 +411,16 @@ func (t *TrunBox) GetSampleInterval(startSampleNr, endSampleNr uint32, baseDecod
// AddFullSample - add Sample part of FullSample
func (t *TrunBox) AddFullSample(s *FullSample) {
t.Samples = append(t.Samples, s.Sample)
t.sampleCount++
}

// AddSample - add a Sample
func (t *TrunBox) AddSample(s Sample) {
t.Samples = append(t.Samples, s)
t.sampleCount++
}

// AddSamples - add a a slice of Sample
func (t *TrunBox) AddSamples(s []Sample) {
t.Samples = append(t.Samples, s...)
t.sampleCount += uint32(len(s))
}

// Duration - calculate total duration of all samples given defaultSampleDuration
Expand All @@ -444,10 +437,14 @@ func (t *TrunBox) Duration(defaultSampleDuration uint32) uint64 {

// GetSampleNrForRelativeTime - get sample number for exact relative time (calculated from summing durations)
func (t *TrunBox) GetSampleNrForRelativeTime(deltaTime uint64, defaultSampleDuration uint32) (uint32, error) {
sampleCount := t.SampleCount()
if sampleCount == 0 {
return 0, fmt.Errorf("no samples in trun")
}
if !t.HasSampleDuration() {
nr := deltaTime / uint64(defaultSampleDuration)
if nr >= uint64(t.sampleCount) {
return 0, fmt.Errorf("time %d is bigger than largest time %d", deltaTime, (t.sampleCount-1)*defaultSampleDuration)
if nr >= uint64(sampleCount) {
return 0, fmt.Errorf("time %d is bigger than largest time %d", deltaTime, (sampleCount-1)*defaultSampleDuration)
}
if nr*uint64(defaultSampleDuration) == deltaTime {
return uint32(nr) + 1, nil
Expand Down

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