/
vmhd.go
89 lines (78 loc) · 2.07 KB
/
vmhd.go
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package mp4
import (
"io"
"github.com/Eyevinn/mp4ff/bits"
)
// 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 := readBoxBody(r, hdr)
if err != nil {
return nil, err
}
sr := bits.NewFixedSliceReader(data)
return DecodeVmhdSR(hdr, startPos, sr)
}
// DecodeVmhdSR - box-specific decode
func DecodeVmhdSR(hdr BoxHeader, startPos uint64, sr bits.SliceReader) (Box, error) {
versionAndFlags := sr.ReadUint32()
b := VmhdBox{
Version: byte(versionAndFlags >> 24),
Flags: versionAndFlags & flagsMask,
GraphicsMode: sr.ReadUint16(),
}
for i := 0; i < 3; i++ {
b.OpColor[i] = sr.ReadUint16()
}
return &b, sr.AccError()
}
// 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 {
sw := bits.NewFixedSliceWriter(int(b.Size()))
err := b.EncodeSW(sw)
if err != nil {
return err
}
_, err = w.Write(sw.Bytes())
return err
}
// EncodeSW - box-specific encode to slicewriter
func (b *VmhdBox) EncodeSW(sw bits.SliceWriter) error {
err := EncodeHeaderSW(b, sw)
if err != nil {
return err
}
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])
}
return sw.AccError()
}
// Info - write box-specific information
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
}