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audio: wav: simplify Stream

This commit is contained in:
faiface 2017-07-14 02:09:36 +02:00
parent 4573035f89
commit 447050b720
1 changed files with 7 additions and 17 deletions
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24
audio/wav/decode.go
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@ -116,47 +116,37 @@ func (s *decoder) Stream(samples [][2]float64) (n int, ok bool) {
if s.err != nil || s.pos >= s.h.DataSize { if s.err != nil || s.pos >= s.h.DataSize {
return 0, false return 0, false
} }
var frameWidth int bytesPerFrame := int(s.h.BytesPerFrame)
switch { p := make([]byte, len(samples)*bytesPerFrame)
case s.h.BitsPerSample == 8 && s.h.NumChans == 1:
frameWidth = 1
case s.h.BitsPerSample == 8 && s.h.NumChans >= 2:
frameWidth = int(s.h.NumChans)
case s.h.BitsPerSample == 16 && s.h.NumChans == 1:
frameWidth = 2
case s.h.BitsPerSample == 16 && s.h.NumChans >= 2:
frameWidth = int(s.h.NumChans) * 2
}
p := make([]byte, len(samples)*frameWidth)
n, err := s.rsc.Read(p) n, err := s.rsc.Read(p)
if err != nil { if err != nil {
s.err = err s.err = err
} }
switch { switch {
case s.h.BitsPerSample == 8 && s.h.NumChans == 1: case s.h.BitsPerSample == 8 && s.h.NumChans == 1:
for i, j := 0, 0; i < n-frameWidth; i, j = i+frameWidth, j+1 { for i, j := 0, 0; i < n-bytesPerFrame; i, j = i+bytesPerFrame, j+1 {
val := float64(p[i])/(1<<8-1)*2 - 1 val := float64(p[i])/(1<<8-1)*2 - 1
samples[j][0] = val samples[j][0] = val
samples[j][1] = val samples[j][1] = val
} }
case s.h.BitsPerSample == 8 && s.h.NumChans >= 2: case s.h.BitsPerSample == 8 && s.h.NumChans >= 2:
for i, j := 0, 0; i < n-frameWidth; i, j = i+frameWidth, j+1 { for i, j := 0, 0; i < n-bytesPerFrame; i, j = i+bytesPerFrame, j+1 {
samples[j][0] = float64(p[i+0])/(1<<8-1)*2 - 1 samples[j][0] = float64(p[i+0])/(1<<8-1)*2 - 1
samples[j][1] = float64(p[i+1])/(1<<8-1)*2 - 1 samples[j][1] = float64(p[i+1])/(1<<8-1)*2 - 1
} }
case s.h.BitsPerSample == 16 && s.h.NumChans == 1: case s.h.BitsPerSample == 16 && s.h.NumChans == 1:
for i, j := 0, 0; i < n-frameWidth; i, j = i+frameWidth, j+1 { for i, j := 0, 0; i < n-bytesPerFrame; i, j = i+bytesPerFrame, j+1 {
val := float64(int16(p[i+0])+int16(p[i+1])*(1<<8)) / (1<<15 - 1) val := float64(int16(p[i+0])+int16(p[i+1])*(1<<8)) / (1<<15 - 1)
samples[j][0] = val samples[j][0] = val
samples[j][1] = val samples[j][1] = val
} }
case s.h.BitsPerSample == 16 && s.h.NumChans >= 2: case s.h.BitsPerSample == 16 && s.h.NumChans >= 2:
for i, j := 0, 0; i <= n-frameWidth; i, j = i+frameWidth, j+1 { for i, j := 0, 0; i <= n-bytesPerFrame; i, j = i+bytesPerFrame, j+1 {
samples[j][0] = float64(int16(p[i+0])+int16(p[i+1])*(1<<8)) / (1<<15 - 1) samples[j][0] = float64(int16(p[i+0])+int16(p[i+1])*(1<<8)) / (1<<15 - 1)
samples[j][1] = float64(int16(p[i+2])+int16(p[i+3])*(1<<8)) / (1<<15 - 1) samples[j][1] = float64(int16(p[i+2])+int16(p[i+3])*(1<<8)) / (1<<15 - 1)
} }
} }
return n / frameWidth, true return n / bytesPerFrame, true
} }
func (s *decoder) Close() error { func (s *decoder) Close() error {