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vmhd.go
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vmhd.go
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package mp4
import (
"io"
"io/ioutil"
)
// VmhdBox - Video Media Header Box (vhmd - mandatory for video tracks)
//
// Contained in : Media Information Box (minf)
type VmhdBox struct {
Version byte
Flags uint32
GraphicsMode uint16
OpColor [3]uint16
}
// CreateVmhd - Create Video Media Header Box
func CreateVmhd() *VmhdBox {
// Flags should be 0x000001 according to ISO/IEC 14496-12 Sec.12.1.2.1
return &VmhdBox{Flags: 0x000001}
}
// DecodeVmhd - box-specific decode
func DecodeVmhd(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()
b := &VmhdBox{
Version: byte(versionAndFlags >> 24),
Flags: versionAndFlags & flagsMask,
GraphicsMode: s.ReadUint16(),
}
for i := 0; i < 3; i++ {
b.OpColor[i] = s.ReadUint16()
}
return b, nil
}
// Type - box-specific type
func (b *VmhdBox) Type() string {
return "vmhd"
}
// Size - calculated size of box
func (b *VmhdBox) Size() uint64 {
return boxHeaderSize + 12
}
// Encode - write box to w
func (b *VmhdBox) 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)
sw.WriteUint16(b.GraphicsMode)
for i := 0; i < 3; i++ {
sw.WriteUint16(b.OpColor[i])
}
_, err = w.Write(buf)
return err
}
func (b *VmhdBox) Info(w io.Writer, specificBoxLevels, indent, indentStep string) error {
bd := newInfoDumper(w, indent, b, int(b.Version), b.Flags)
return bd.err
}