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examples/audiopanning: Bug fix: Align the buffer size

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Closes #1598
This commit is contained in:
Hajime Hoshi 2021-04-20 02:33:53 +09:00
parent 24dc20e80e
commit 7f8c3a13b3
1 changed files with 21 additions and 6 deletions
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27
examples/audiopanning/main.go
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@ -145,14 +145,29 @@ func main() {
type StereoPanStream struct { type StereoPanStream struct {
io.ReadSeeker io.ReadSeeker
pan float64 // -1: left; 0: center; 1: right pan float64 // -1: left; 0: center; 1: right
buf []byte
} }
func (s *StereoPanStream) Read(p []byte) (n int, err error) { func (s *StereoPanStream) Read(p []byte) (int, error) {
n, err = s.ReadSeeker.Read(p) // If the stream has a buffer that was read in the previous time, use this first.
if err != nil { var bufN int
return if len(s.buf) > 0 {
bufN = copy(p, s.buf)
s.buf = s.buf[bufN:]
} }
readN, err := s.ReadSeeker.Read(p[bufN:])
if err != nil && err != io.EOF {
return 0, err
}
// Align the buffer size in multiples of 4. The extra part is pushed to the buffer for the
// next time.
totalN := bufN + readN
extra := totalN - totalN/4*4
s.buf = append(s.buf, p[totalN-extra:totalN]...)
alignedN := totalN - extra
// This implementation uses a linear scale, ranging from -1 to 1, for stereo or mono sounds. // This implementation uses a linear scale, ranging from -1 to 1, for stereo or mono sounds.
// If pan = 0.0, the balance for the sound in each speaker is at 100% left and 100% right. // If pan = 0.0, the balance for the sound in each speaker is at 100% left and 100% right.
// When pan is -1.0, only the left channel of the stereo sound is audible, when pan is 1.0, // When pan is -1.0, only the left channel of the stereo sound is audible, when pan is 1.0,
@ -160,7 +175,7 @@ func (s *StereoPanStream) Read(p []byte) (n int, err error) {
// https://docs.unity3d.com/ScriptReference/AudioSource-panStereo.html // https://docs.unity3d.com/ScriptReference/AudioSource-panStereo.html
ls := math.Min(s.pan*-1+1, 1) ls := math.Min(s.pan*-1+1, 1)
rs := math.Min(s.pan+1, 1) rs := math.Min(s.pan+1, 1)
for i := 0; i < len(p); i += 4 { for i := 0; i < alignedN; i += 4 {
lc := int16(float64(int16(p[i])|int16(p[i+1])<<8) * ls) lc := int16(float64(int16(p[i])|int16(p[i+1])<<8) * ls)
rc := int16(float64(int16(p[i+2])|int16(p[i+3])<<8) * rs) rc := int16(float64(int16(p[i+2])|int16(p[i+3])<<8) * rs)
@ -169,7 +184,7 @@ func (s *StereoPanStream) Read(p []byte) (n int, err error) {
p[i+2] = byte(rc) p[i+2] = byte(rc)
p[i+3] = byte(rc >> 8) p[i+3] = byte(rc >> 8)
} }
return return alignedN, err
} }
func (s *StereoPanStream) SetPan(pan float64) { func (s *StereoPanStream) SetPan(pan float64) {