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114 lines
2.6 KiB
114 lines
2.6 KiB
package aac |
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import ( |
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"fmt" |
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"io" |
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"github.com/gwuhaolin/livego/av" |
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) |
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type mpegExtension struct { |
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objectType byte |
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sampleRate byte |
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} |
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type mpegCfgInfo struct { |
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objectType byte |
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sampleRate byte |
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channel byte |
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sbr byte |
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ps byte |
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frameLen byte |
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exceptionLogTs int64 |
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extension *mpegExtension |
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} |
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var aacRates = []int{96000, 88200, 64000, 48000, 44100, 32000, 24000, 22050, 16000, 12000, 11025, 8000, 7350} |
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var ( |
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specificBufInvalid = fmt.Errorf("audio mpegspecific error") |
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audioBufInvalid = fmt.Errorf("audiodata invalid") |
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) |
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const ( |
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adtsHeaderLen = 7 |
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) |
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type Parser struct { |
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gettedSpecific bool |
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adtsHeader []byte |
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cfgInfo *mpegCfgInfo |
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} |
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func NewParser() *Parser { |
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return &Parser{ |
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gettedSpecific: false, |
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cfgInfo: &mpegCfgInfo{}, |
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adtsHeader: make([]byte, adtsHeaderLen), |
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} |
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} |
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func (parser *Parser) specificInfo(src []byte) error { |
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if len(src) < 2 { |
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return specificBufInvalid |
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} |
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parser.gettedSpecific = true |
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parser.cfgInfo.objectType = (src[0] >> 3) & 0xff |
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parser.cfgInfo.sampleRate = ((src[0] & 0x07) << 1) | src[1]>>7 |
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parser.cfgInfo.channel = (src[1] >> 3) & 0x0f |
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return nil |
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} |
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func (parser *Parser) adts(src []byte, w io.Writer) error { |
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if len(src) <= 0 || !parser.gettedSpecific { |
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return audioBufInvalid |
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} |
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frameLen := uint16(len(src)) + 7 |
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//first write adts header |
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parser.adtsHeader[0] = 0xff |
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parser.adtsHeader[1] = 0xf1 |
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parser.adtsHeader[2] &= 0x00 |
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parser.adtsHeader[2] = parser.adtsHeader[2] | (parser.cfgInfo.objectType-1)<<6 |
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parser.adtsHeader[2] = parser.adtsHeader[2] | (parser.cfgInfo.sampleRate)<<2 |
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parser.adtsHeader[3] &= 0x00 |
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parser.adtsHeader[3] = parser.adtsHeader[3] | (parser.cfgInfo.channel<<2)<<4 |
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parser.adtsHeader[3] = parser.adtsHeader[3] | byte((frameLen<<3)>>14) |
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parser.adtsHeader[4] &= 0x00 |
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parser.adtsHeader[4] = parser.adtsHeader[4] | byte((frameLen<<5)>>8) |
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parser.adtsHeader[5] &= 0x00 |
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parser.adtsHeader[5] = parser.adtsHeader[5] | byte(((frameLen<<13)>>13)<<5) |
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parser.adtsHeader[5] = parser.adtsHeader[5] | (0x7C<<1)>>3 |
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parser.adtsHeader[6] = 0xfc |
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if _, err := w.Write(parser.adtsHeader[0:]); err != nil { |
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return err |
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} |
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if _, err := w.Write(src); err != nil { |
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return err |
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} |
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return nil |
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} |
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func (parser *Parser) SampleRate() int { |
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rate := 44100 |
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if parser.cfgInfo.sampleRate <= byte(len(aacRates)-1) { |
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rate = aacRates[parser.cfgInfo.sampleRate] |
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} |
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return rate |
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} |
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func (parser *Parser) Parse(b []byte, packetType uint8, w io.Writer) (err error) { |
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switch packetType { |
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case av.AAC_SEQHDR: |
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err = parser.specificInfo(b) |
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case av.AAC_RAW: |
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err = parser.adts(b, w) |
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} |
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return |
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}
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