/
realtime.go
94 lines (80 loc) · 1.9 KB
/
realtime.go
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package audio
import (
"sync"
"time"
)
type realtimeStream struct {
stream Stream
lastError error
buffer []int32
readPosition int
usageLock *sync.Mutex
}
// NewRealtimeStream converts a stream into a buffered stream for use in
// realtime applications, such as audio over a network.
func NewRealtimeStream(stream Stream, bufferSize int) Stream {
newStream := &realtimeStream{
stream: stream,
lastError: nil,
buffer: make([]int32, bufferSize),
readPosition: bufferSize,
usageLock: new(sync.Mutex),
}
go newStream.run()
return newStream
}
func (r *realtimeStream) run() {
buffer := make([]int32, 1024)
for {
n, err := r.stream.Read(buffer)
r.usageLock.Lock()
r.buffer = append(r.buffer[n:], buffer[:n]...)
r.readPosition -= n
if r.readPosition < 0 {
r.readPosition = len(r.buffer) / 2
}
if err != nil {
r.lastError = err
r.usageLock.Unlock()
return
}
r.usageLock.Unlock()
}
}
func (r *realtimeStream) Read(dst interface{}) (int, error) {
dstLen := SliceLength(dst)
r.usageLock.Lock()
if dstLen > len(r.buffer)/2 {
dstLen = len(r.buffer) / 2
}
r.usageLock.Unlock()
for {
r.usageLock.Lock()
available := (len(r.buffer) - r.readPosition)
if available >= dstLen || r.lastError != nil {
if dstLen > available {
err := ReadFromInt32(dst, r.buffer[r.readPosition:], available)
r.readPosition += available
if r.lastError != nil {
r.usageLock.Unlock()
return available, r.lastError
}
r.usageLock.Unlock()
return available, err
}
err := ReadFromInt32(dst, r.buffer[r.readPosition:], dstLen)
r.readPosition += dstLen
if r.lastError != nil {
r.usageLock.Unlock()
return available, r.lastError
}
r.usageLock.Unlock()
return dstLen, err
}
r.usageLock.Unlock()
time.Sleep(time.Millisecond * 10)
}
}
func (r *realtimeStream) SampleRate() int {
return r.stream.SampleRate()
}