Alexey Khit
117 lines
2.5 KiB
Go
117 lines
2.5 KiB
Go
package pcm
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import (
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"github.com/AlexxIT/go2rtc/pkg/core"
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"github.com/pion/rtp"
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)
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func Resample(codec *core.Codec, sampleRate uint32, handler core.HandlerFunc) core.HandlerFunc {
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n := float32(codec.ClockRate) / float32(sampleRate)
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switch codec.Name {
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case core.CodecPCMA:
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return DownsampleByte(PCMAtoPCM, PCMtoPCMA, n, handler)
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case core.CodecPCMU:
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return DownsampleByte(PCMUtoPCM, PCMtoPCMU, n, handler)
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case core.CodecPCM:
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if n == 1 {
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return ResamplePCM(PCMtoPCMA, handler)
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}
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return DownsamplePCM(PCMtoPCMA, n, handler)
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}
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panic(core.Caller())
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}
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func DownsampleByte(
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toPCM func(byte) int16, fromPCM func(int16) byte, n float32, handler core.HandlerFunc,
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) core.HandlerFunc {
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var sampleN, sampleSum float32
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var ts uint32
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return func(packet *rtp.Packet) {
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samples := len(packet.Payload)
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newLen := uint32((float32(samples) + sampleN) / n)
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oldSamples := packet.Payload
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newSamples := make([]byte, newLen)
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var i int
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for _, sample := range oldSamples {
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sampleSum += float32(toPCM(sample))
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if sampleN++; sampleN >= n {
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newSamples[i] = fromPCM(int16(sampleSum / n))
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i++
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sampleSum = 0
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sampleN -= n
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}
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}
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ts += newLen
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clone := *packet
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clone.Payload = newSamples
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clone.Timestamp = ts
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handler(&clone)
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}
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}
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func ResamplePCM(fromPCM func(int16) byte, handler core.HandlerFunc) core.HandlerFunc {
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var ts uint32
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return func(packet *rtp.Packet) {
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len1 := len(packet.Payload)
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len2 := len1 / 2
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oldSamples := packet.Payload
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newSamples := make([]byte, len2)
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var i2 int
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for i1 := 0; i1 < len1; i1 += 2 {
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sample := int16(uint16(oldSamples[i1])<<8 | uint16(oldSamples[i1+1]))
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newSamples[i2] = fromPCM(sample)
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i2++
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}
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ts += uint32(len2)
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clone := *packet
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clone.Payload = newSamples
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clone.Timestamp = ts
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handler(&clone)
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}
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}
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func DownsamplePCM(fromPCM func(int16) byte, n float32, handler core.HandlerFunc) core.HandlerFunc {
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var sampleN, sampleSum float32
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var ts uint32
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return func(packet *rtp.Packet) {
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samples := len(packet.Payload) / 2
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newLen := uint32((float32(samples) + sampleN) / n)
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oldSamples := packet.Payload
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newSamples := make([]byte, newLen)
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var i2 int
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for i1 := 0; i1 < len(packet.Payload); i1 += 2 {
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sampleSum += float32(int16(uint16(oldSamples[i1])<<8 | uint16(oldSamples[i1+1])))
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if sampleN++; sampleN >= n {
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newSamples[i2] = fromPCM(int16(sampleSum / n))
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i2++
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sampleSum = 0
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sampleN -= n
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}
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}
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ts += newLen
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clone := *packet
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clone.Payload = newSamples
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clone.Timestamp = ts
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handler(&clone)
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}
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}
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