/
SegmentIndex.go
177 lines (164 loc) · 4.3 KB
/
SegmentIndex.go
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package sofia
import (
"encoding/binary"
"io"
)
// this is the size of the fragment, typically `moof` + `mdat`
func (r Reference) ReferencedSize() uint32 {
return r[0] & r.mask()
}
// ISO/IEC 14496-12
// aligned(8) class SegmentIndexBox extends FullBox('sidx', version, 0) {
// unsigned int(32) reference_ID;
// unsigned int(32) timescale;
// if (version==0) {
// unsigned int(32) earliest_presentation_time;
// unsigned int(32) first_offset;
// } else {
// unsigned int(64) earliest_presentation_time;
// unsigned int(64) first_offset;
// }
// unsigned int(16) reserved = 0;
// unsigned int(16) reference_count;
// for(i=1; i <= reference_count; i++) {
// bit (1) reference_type;
// unsigned int(31) referenced_size;
// unsigned int(32) subsegment_duration;
// bit(1) starts_with_SAP;
// unsigned int(3) SAP_type;
// unsigned int(28) SAP_delta_time;
// }
// }
type SegmentIndex struct {
BoxHeader BoxHeader
FullBoxHeader FullBoxHeader
ReferenceId uint32
Timescale uint32
EarliestPresentationTime []byte
FirstOffset []byte
Reserved uint16
ReferenceCount uint16
Reference []Reference
}
type Reference [3]uint32
func (Reference) mask() uint32 {
return 0xFFFFFFFF >> 1
}
func (r *Reference) read(src io.Reader) error {
return binary.Read(src, binary.BigEndian, r)
}
func (r Reference) set_referenced_size(v uint32) {
r[0] &= ^r.mask()
r[0] |= v
}
func (r Reference) write(dst io.Writer) error {
return binary.Write(dst, binary.BigEndian, r)
}
func (s *SegmentIndex) Append(size uint32) {
var r Reference
r.set_referenced_size(size)
s.Reference = append(s.Reference, r)
s.ReferenceCount++
s.BoxHeader.Size = uint32(s.get_size())
}
func (s *SegmentIndex) New() {
copy(s.BoxHeader.Type[:], "sidx")
}
func (s SegmentIndex) get_size() int {
v, _ := s.BoxHeader.get_size()
v += binary.Size(s.FullBoxHeader)
v += binary.Size(s.ReferenceId)
v += binary.Size(s.Timescale)
v += binary.Size(s.EarliestPresentationTime)
v += binary.Size(s.FirstOffset)
v += binary.Size(s.Reserved)
v += binary.Size(s.ReferenceCount)
return v + binary.Size(s.Reference)
}
func (s *SegmentIndex) read(r io.Reader) error {
err := s.FullBoxHeader.read(r)
if err != nil {
return err
}
err = binary.Read(r, binary.BigEndian, &s.ReferenceId)
if err != nil {
return err
}
err = binary.Read(r, binary.BigEndian, &s.Timescale)
if err != nil {
return err
}
if s.FullBoxHeader.Version == 0 {
s.EarliestPresentationTime = make([]byte, 4)
s.FirstOffset = make([]byte, 4)
} else {
s.EarliestPresentationTime = make([]byte, 8)
s.FirstOffset = make([]byte, 8)
}
_, err = io.ReadFull(r, s.EarliestPresentationTime)
if err != nil {
return err
}
_, err = io.ReadFull(r, s.FirstOffset)
if err != nil {
return err
}
err = binary.Read(r, binary.BigEndian, &s.Reserved)
if err != nil {
return err
}
err = binary.Read(r, binary.BigEndian, &s.ReferenceCount)
if err != nil {
return err
}
s.Reference = make([]Reference, s.ReferenceCount)
for i, value := range s.Reference {
err := value.read(r)
if err != nil {
return err
}
s.Reference[i] = value
}
return nil
}
func (s SegmentIndex) write(w io.Writer) error {
err := s.BoxHeader.write(w)
if err != nil {
return err
}
err = s.FullBoxHeader.write(w)
if err != nil {
return err
}
err = binary.Write(w, binary.BigEndian, s.ReferenceId)
if err != nil {
return err
}
err = binary.Write(w, binary.BigEndian, s.Timescale)
if err != nil {
return err
}
_, err = w.Write(s.EarliestPresentationTime)
if err != nil {
return err
}
_, err = w.Write(s.FirstOffset)
if err != nil {
return err
}
err = binary.Write(w, binary.BigEndian, s.Reserved)
if err != nil {
return err
}
err = binary.Write(w, binary.BigEndian, s.ReferenceCount)
if err != nil {
return err
}
for _, value := range s.Reference {
err := value.write(w)
if err != nil {
return err
}
}
return nil
}