85 lines
3.4 KiB
Go
85 lines
3.4 KiB
Go
// Copyright 2024 Martin Riedl
|
||
//
|
||
// Licensed under the Apache License, Version 2.0 (the "License");
|
||
// you may not use this file except in compliance with the License.
|
||
// You may obtain a copy of the License at
|
||
//
|
||
// http://www.apache.org/licenses/LICENSE-2.0
|
||
//
|
||
// Unless required by applicable law or agreed to in writing, software
|
||
// distributed under the License is distributed on an "AS IS" BASIS,
|
||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||
// See the License for the specific language governing permissions and
|
||
// limitations under the License.
|
||
|
||
package gomp4
|
||
|
||
import (
|
||
"encoding/binary"
|
||
"time"
|
||
)
|
||
|
||
// MediaHeaderBox media header box struct
|
||
//
|
||
// 8.4.2 Media Header Box
|
||
//
|
||
// Box Type: ‘mdhd’
|
||
// Container: Media Box (‘mdia’)
|
||
// Mandatory: Yes
|
||
// Quantity: Exactly one
|
||
//
|
||
// The media header declares overall information that is media‐independent, and relevant to
|
||
// characteristics of the media in a track.
|
||
type MediaHeaderBox struct {
|
||
*FullBox
|
||
// is an integer that declares the creation time of the media in this track (in
|
||
// seconds since midnight, Jan. 1, 1904, in UTC time).
|
||
CreationTimeV0 time.Time
|
||
// is an integer that declares the creation time of the media in this track (in
|
||
// seconds since midnight, Jan. 1, 1904, in UTC time).
|
||
CreationTimeV1 time.Time
|
||
// is an integer that declares the most recent time the media in this track was
|
||
// modified (in seconds since midnight, Jan. 1, 1904, in UTC time).
|
||
ModificationTimeV0 time.Time
|
||
// is an integer that declares the most recent time the media in this track was
|
||
// modified (in seconds since midnight, Jan. 1, 1904, in UTC time).
|
||
ModificationTimeV1 time.Time
|
||
// is an integer that specifies the time‐scale for this media; this is the number of time
|
||
// units that pass in one second. For example, a time coordinate system that measures time in
|
||
// sixtieths of a second has a time scale of 60.
|
||
Timescale uint32
|
||
// is an integer that declares the duration of this media (in the scale of the timescale). If the
|
||
// duration cannot be determined then duration is set to all 1s.
|
||
DurationV0 uint32
|
||
// is an integer that declares the duration of this media (in the scale of the timescale). If the
|
||
// duration cannot be determined then duration is set to all 1s.
|
||
DurationV1 uint64
|
||
|
||
// TODO: parse language language
|
||
}
|
||
|
||
// ParseMediaHeaderBox creates a new Track Header Box struct
|
||
func ParseMediaHeaderBox(filePosition uint64, headerSize uint32, content []byte) *MediaHeaderBox {
|
||
box := &MediaHeaderBox{
|
||
FullBox: newFullBox(&Box{filePosition, headerSize}, content[0:4]),
|
||
}
|
||
|
||
position := 4
|
||
if box.Version == 1 {
|
||
box.CreationTimeV1 = since1904ToTime(int64(binary.BigEndian.Uint64(content[position : position+8])))
|
||
box.ModificationTimeV1 = since1904ToTime(int64(binary.BigEndian.Uint64(content[position+8 : position+16])))
|
||
box.Timescale = binary.BigEndian.Uint32(content[position+16 : position+20])
|
||
box.DurationV1 = binary.BigEndian.Uint64(content[position+20 : position+28])
|
||
position += 28
|
||
} else { // version == 0
|
||
box.CreationTimeV0 = since1904ToTime(int64(binary.BigEndian.Uint32(content[position : position+4])))
|
||
box.ModificationTimeV0 = since1904ToTime(int64(binary.BigEndian.Uint32(content[position+4 : position+8])))
|
||
box.Timescale = binary.BigEndian.Uint32(content[position+8 : position+12])
|
||
box.DurationV0 = binary.BigEndian.Uint32(content[position+12 : position+16])
|
||
position += 16
|
||
}
|
||
|
||
// TODO: parse language language
|
||
|
||
return box
|
||
}
|