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package avc
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import (
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"errors"
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"github.com/q191201771/nezha/pkg/bele"
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"io"
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)
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var avcErr = errors.New("avc: fxxk")
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var NaluStartCode = []byte{0x0, 0x0, 0x0, 0x1}
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var NaluUintTypeMapping = map[uint8]string{
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1: "SLICE",
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5: "IDR",
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6: "SEI",
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7: "SPS",
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8: "PPS",
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9: "AUD",
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}
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// 从 rtmp avc sequence header 中解析 sps 和 pps
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// @param <payload> rtmp message的payload部分 或者 flv tag的payload部分
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func ParseAVCSeqHeader(payload []byte) (sps, pps []byte, err error) {
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// TODO chef: check if read out of <payload> range
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if payload[0] != 0x17 || payload[1] != 0x00 || payload[2] != 0 || payload[3] != 0 || payload[4] != 0 {
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err = avcErr
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return
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}
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// H.264-AVC-ISO_IEC_14496-15.pdf
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// 5.2.4 Decoder configuration information
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//configurationVersion := payload[5]
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//avcProfileIndication := payload[6]
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//profileCompatibility := payload[7]
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//avcLevelIndication := payload[8]
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//lengthSizeMinusOne := payload[9] & 0x03
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index := 10
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numOfSPS := int(payload[index] & 0x1F)
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index++
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// TODO chef: if the situation of multi sps exist?
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// only take the last one.
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for i := 0; i < numOfSPS; i++ {
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lenOfSPS := int(bele.BEUint16(payload[index:]))
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index += 2
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sps = append(sps, payload[index:index+lenOfSPS]...)
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index += lenOfSPS
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}
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numOfPPS := int(payload[index] & 0x1F)
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index++
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for i := 0; i < numOfPPS; i++ {
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lenOfPPS := int(bele.BEUint16(payload[index:]))
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index += 2
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pps = append(pps, payload[index:index+lenOfPPS]...)
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index += lenOfPPS
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}
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return
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}
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// 将rtmp avc数据转换成avc裸流
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// @param <payload> rtmp message的payload部分 或者 flv tag的payload部分
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func CaptureAVC(w io.Writer, payload []byte) error {
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// sps pps
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if payload[0] == 0x17 && payload[1] == 0x00 {
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sps, pps, err := ParseAVCSeqHeader(payload)
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if err != nil {
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return err
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}
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//utilErrors.PanicIfErrorOccur(err)
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_, _ = w.Write(NaluStartCode)
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_, _ = w.Write(sps)
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_, _ = w.Write(NaluStartCode)
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_, _ = w.Write(pps)
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return nil
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}
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// payload中可能存在多个nalu
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// 先跳过前面type的2字节，以及composition time的3字节
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for i := 5; i != len(payload); {
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naluLen := int(bele.BEUint32(payload[i:]))
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i += 4
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//naluUintType := payload[i] & 0x1f
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//log.Debugf("naluLen:%d t:%d %s\n", naluLen, naluUintType, avc.NaluUintTypeMapping[naluUintType])
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_, _ = w.Write(NaluStartCode)
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_, _ = w.Write(payload[i : i+naluLen])
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i += naluLen
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break
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}
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return nil
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}
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