mp4/Box.go
2024-10-12 15:38:41 +02:00

67 lines
2 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"
const (
boxSizeLength uint32 = 4
boxTypeLength uint32 = 4
// BoxTypeFileType File Type Box
BoxTypeFileType = "ftyp"
// BoxTypeMediaData Media Data Box
BoxTypeMediaData = "mdat"
// BoxTypeMovie Movie Box
BoxTypeMovie = "moov"
// BoxTypeMovieFragment Movie Fragment Box
BoxTypeMovieFragment = "moof"
// BoxTypeMovieFragmentHeader Movie Fragment Header Box
BoxTypeMovieFragmentHeader = "mfhd"
// BoxTypeTrackFragment Track Fragment Box
BoxTypeTrackFragment = "traf"
// BoxTypeTrackFragmentHeader Track Fragment Header
BoxTypeTrackFragmentHeader = "tfhd"
// BoxTypeTrackFragmentRun Track Fragment Run Box
BoxTypeTrackFragmentRun = "trun"
)
// Box is an abstract box struct
type Box struct {
FilePosition uint64
HeaderSize uint32
}
// FullBox is an abstract box type extending base box
type FullBox struct {
*Box
Version uint8
Flag []byte
flagUInt32 uint32
}
// newFullBox parses based on 4 bytes data the version number (first byte) and the flags (bytes 2 - 4)
func newFullBox(box *Box, data []byte) *FullBox {
fullBox := &FullBox{Box: box, Version: data[0], Flag: data[1:4]}
// build uint32 for flags (used for easier matching)
flag4Bytes := append(make([]byte, 1), fullBox.Flag...)
fullBox.flagUInt32 = binary.BigEndian.Uint32(flag4Bytes)
// extend header size
fullBox.HeaderSize = fullBox.HeaderSize + 4
return fullBox
}