mirror of https://bitbucket.org/ausocean/av.git
143 lines
3.4 KiB
Go
143 lines
3.4 KiB
Go
/*
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NAME
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flv.go
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DESCRIPTION
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See Readme.md
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AUTHORS
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Saxon A. Nelson-Milton <saxon@ausocean.org>
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Dan Kortschak <dan@ausocean.org>
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LICENSE
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flv.go is Copyright (C) 2017 the Australian Ocean Lab (AusOcean)
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It is free software: you can redistribute it and/or modify them
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under the terms of the GNU General Public License as published by the
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Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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It is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received a copy of the GNU General Public License
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along with revid in gpl.txt. If not, see http://www.gnu.org/licenses.
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*/
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// See https://wwwimages2.adobe.com/content/dam/acom/en/devnet/flv/video_file_format_spec_v10.pdf
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// for format specification.
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// Package flv provides FLV encoding and related functions.
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package flv
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import "encoding/binary"
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const (
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maxVideoTagSize = 10000
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maxAudioTagSize = 10000
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)
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const (
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VideoTagType = 9
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AudioTagType = 8
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KeyFrameType = 1
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InterFrameType = 2
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H264 = 7
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AVCNALU = 1
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SequenceHeader = 0
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DataHeaderLength = 5
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NoTimestampExtension = 0
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AACAudioFormat = 10
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PCMAudioFormat = 0
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)
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const (
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sizeofFLVTagHeader = 11
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sizeofPrevTagSize = 4
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)
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const version = 0x01
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// FLV is big-endian.
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var order = binary.BigEndian
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// orderPutUint24 is a binary.BigEndian method look-alike for
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// writing 24 bit words to a byte slice.
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func orderPutUint24(b []byte, v uint32) {
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_ = b[2] // early bounds check to guarantee safety of writes below
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b[0] = byte(v >> 16)
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b[1] = byte(v >> 8)
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b[2] = byte(v)
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}
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type VideoTag struct {
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TagType uint8
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DataSize uint32
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Timestamp uint32
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TimestampExtended uint8
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FrameType uint8
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Codec uint8
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PacketType uint8
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CompositionTime uint32
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Data []byte
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PrevTagSize uint32
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}
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func (t *VideoTag) Bytes() []byte {
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// FIXME(kortschak): This should probably be an encoding.BinaryMarshaler.
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// This will allow handling of invalid field values.
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b := make([]byte, t.DataSize+sizeofFLVTagHeader+sizeofPrevTagSize)
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b[0] = t.TagType
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orderPutUint24(b[1:4], t.DataSize)
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orderPutUint24(b[4:7], t.Timestamp)
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b[7] = t.TimestampExtended
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b[11] = t.FrameType<<4 | t.Codec
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b[12] = t.PacketType
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orderPutUint24(b[13:16], t.CompositionTime)
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copy(b[16:], t.Data)
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order.PutUint32(b[len(b)-4:], t.PrevTagSize)
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return b
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}
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type AudioTag struct {
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TagType uint8
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DataSize uint32
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Timestamp uint32
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TimestampExtended uint8
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SoundFormat uint8
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SoundRate uint8
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SoundSize bool
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SoundType bool
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Data []byte
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PrevTagSize uint32
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}
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func (t *AudioTag) Bytes() []byte {
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// FIXME(kortschak): This should probably be an encoding.BinaryMarshaler.
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// This will allow handling of invalid field values.
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b := make([]byte, t.DataSize+sizeofFLVTagHeader+sizeofPrevTagSize)
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b[0] = t.TagType
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orderPutUint24(b[1:4], t.DataSize)
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orderPutUint24(b[4:7], t.Timestamp)
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b[7] = t.TimestampExtended
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b[11] = t.SoundFormat<<4 | t.SoundRate<<2 | btb(t.SoundSize)<<1 | btb(t.SoundType)
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copy(b[12:], t.Data)
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order.PutUint32(b[len(b)-4:], t.PrevTagSize)
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return b
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}
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func btb(b bool) byte {
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if b {
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return 1
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}
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return 0
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}
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