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saio.go
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saio.go
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package mp4
import (
"io"
"io/ioutil"
)
// SaioBox - Sample Auxiliary Information Offsets Box (saiz)
type SaioBox struct {
Version byte
Flags uint32
AuxInfoType string // Used for Common Encryption Scheme (4-bytes uint32 according to spec)
AuxInfoTypeParameter uint32
Offset []int64
}
// DecodeSaio - box-specific decode
func DecodeSaio(hdr *boxHeader, startPos uint64, r io.Reader) (Box, error) {
data, err := ioutil.ReadAll(r)
if err != nil {
return nil, err
}
s := NewSliceReader(data)
versionAndFlags := s.ReadUint32()
version := byte(versionAndFlags >> 24)
b := &SaioBox{
Version: version,
Flags: versionAndFlags & flagsMask,
}
if b.Flags&0x01 != 0 {
b.AuxInfoType = s.ReadFixedLengthString(4)
b.AuxInfoTypeParameter = s.ReadUint32()
}
entryCount := s.ReadUint32()
if version == 0 {
for i := uint32(0); i < entryCount; i++ {
b.Offset = append(b.Offset, int64(s.ReadInt32()))
}
} else {
for i := uint32(0); i < entryCount; i++ {
b.Offset = append(b.Offset, s.ReadInt64())
}
}
return b, nil
}
// Type - return box type
func (b *SaioBox) Type() string {
return "saio"
}
// Size - return calculated size
func (b *SaioBox) Size() uint64 {
size := uint64(boxHeaderSize) + 8
if b.Flags&0x01 != 0 {
size += 8
}
if b.Version == 0 {
size += 4 * uint64(len(b.Offset))
} else {
size += 8 * uint64(len(b.Offset))
}
return size
}
// Encode - write box to w
func (b *SaioBox) Encode(w io.Writer) error {
err := EncodeHeader(b, w)
if err != nil {
return err
}
buf := makebuf(b)
sw := NewSliceWriter(buf)
versionAndFlags := (uint32(b.Version) << 24) + b.Flags
sw.WriteUint32(versionAndFlags)
if b.Flags&0x01 != 0 {
sw.WriteString(b.AuxInfoType, false)
sw.WriteUint32(b.AuxInfoTypeParameter)
}
sw.WriteUint32(uint32(len(b.Offset)))
if b.Version == 0 {
for i := 0; i < len(b.Offset); i++ {
sw.WriteInt32(int32(b.Offset[i]))
}
} else {
for i := 0; i < len(b.Offset); i++ {
sw.WriteInt64(b.Offset[i])
}
}
_, err = w.Write(buf)
return err
}
// Info - write SaioBox details. Get offset list with level >= 1
func (b *SaioBox) Info(w io.Writer, specificBoxLevels, indent, indentStep string) (err error) {
bd := newInfoDumper(w, indent, b, int(b.Version), b.Flags)
if b.Flags&0x01 != 0 {
bd.write(" - auxInfoType: %s", b.AuxInfoType)
bd.write(" - auxInfoTypeParameter: %d", b.AuxInfoTypeParameter)
}
bd.write(" - sampleCount: %d", len(b.Offset))
level := getInfoLevel(b, specificBoxLevels)
if level > 0 {
for i := 0; i < len(b.Offset); i++ {
bd.write(" - offset[%d]=%d", i+1, b.Offset[i])
}
}
return bd.err
}