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monibuca/plugin/mp4/pkg/box/stco.go
2024-09-12 18:23:36 +08:00

101 lines
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package box
import (
"encoding/binary"
"io"
)
// aligned(8) class ChunkOffsetBox
// extends FullBox(stco, version = 0, 0) {
// unsigned int(32) entry_count;
// for (i=1; i <= entry_count; i++) {
// unsigned int(32) chunk_offset;
// }
// }
// aligned(8) class ChunkLargeOffsetBox
// extends FullBox(co64, version = 0, 0) {
// unsigned int(32) entry_count;
// for (i=1; i <= entry_count; i++) {
// unsigned int(64) chunk_offset;
// }
// }
type ChunkOffsetBox []uint64
func (stco *ChunkOffsetBox) Decode(r io.Reader) (offset int, err error) {
var fullbox FullBox
if _, err = fullbox.Decode(r); err != nil {
return
}
tmp := make([]byte, 4)
if _, err = io.ReadFull(r, tmp); err != nil {
return
}
offset = 8
l := binary.BigEndian.Uint32(tmp)
*stco = make([]uint64, l)
buf := make([]byte, l*4)
if _, err = io.ReadFull(r, buf); err != nil {
return
}
idx := 0
for i := 0; i < int(l); i++ {
(*stco)[i] = uint64(binary.BigEndian.Uint32(buf[idx:]))
idx += 4
}
offset += idx
return
}
func (stco ChunkOffsetBox) Encode() (int, []byte) {
var fullbox *FullBox
l := len(stco)
if stco[l-1] > 0xFFFFFFFF {
fullbox = NewFullBox(TypeCO64, 0)
fullbox.Box.Size = FullBoxLen + 4 + 8*uint64(l)
} else {
fullbox = NewFullBox(TypeSTCO, 0)
fullbox.Box.Size = FullBoxLen + 4 + 4*uint64(l)
}
offset, buf := fullbox.Encode()
binary.BigEndian.PutUint32(buf[offset:], uint32(l))
offset += 4
for i := 0; i < int(l); i++ {
if fullbox.Box.Type == TypeCO64 {
binary.BigEndian.PutUint64(buf[offset:], uint64(stco[i]))
offset += 8
} else {
binary.BigEndian.PutUint32(buf[offset:], uint32(stco[i]))
offset += 4
}
}
return offset, buf
}
type ChunkLargeOffsetBox ChunkOffsetBox
func (co64 *ChunkLargeOffsetBox) Decode(r io.Reader) (offset int, err error) {
var fullbox FullBox
if _, err = fullbox.Decode(r); err != nil {
return
}
tmp := make([]byte, 4)
if _, err = io.ReadFull(r, tmp); err != nil {
return
}
offset = 8
l := binary.BigEndian.Uint32(tmp)
*co64 = make([]uint64, l)
buf := make([]byte, l*8)
if _, err = io.ReadFull(r, buf); err != nil {
return
}
idx := 0
for i := 0; i < int(l); i++ {
(*co64)[i] = binary.BigEndian.Uint64(buf[idx:])
idx += 8
}
offset += idx
return
}