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audio/vorbis: Avoid appending buffer

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This commit is contained in:
Hajime Hoshi 2016-12-08 02:14:34 +09:00
parent 20ae2e0fc8
commit 8ed07e0822
1 changed files with 14 additions and 6 deletions
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20
audio/vorbis/vorbis.go
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@ -26,6 +26,7 @@ import (
type decoded struct { type decoded struct {
data []float32 data []float32
totalBytes int totalBytes int
readBytes int
posInBytes int posInBytes int
source io.Closer source io.Closer
decoder *oggvorbis.Reader decoder *oggvorbis.Reader
@ -34,10 +35,18 @@ type decoded struct {
func (d *decoded) readUntil(posInBytes int) error { func (d *decoded) readUntil(posInBytes int) error {
c := 0 c := 0
buffer := make([]float32, 8192) buffer := make([]float32, 8192)
for len(d.data) < posInBytes/2 { for d.readBytes < posInBytes {
n, err := d.decoder.Read(buffer) n, err := d.decoder.Read(buffer)
if n > 0 { if n > 0 {
d.data = append(d.data, buffer[:n]...) // Actual read bytes might exceed the total bytes.
if d.readBytes+n*2 > d.totalBytes {
n = (d.totalBytes - d.readBytes) / 2
}
p := d.readBytes / 2
for i := 0; i < n; i++ {
d.data[p+i] = buffer[i]
}
d.readBytes += n * 2
} }
if err == io.EOF { if err == io.EOF {
if err := d.source.Close(); err != nil { if err := d.source.Close(); err != nil {
@ -57,8 +66,7 @@ func (d *decoded) readUntil(posInBytes int) error {
} }
func (d *decoded) Read(b []uint8) (int, error) { func (d *decoded) Read(b []uint8) (int, error) {
total := d.totalBytes l := d.totalBytes - d.posInBytes
l := total - d.posInBytes
if l > len(b) { if l > len(b) {
l = len(b) l = len(b)
} }
@ -77,7 +85,7 @@ func (d *decoded) Read(b []uint8) (int, error) {
b[2*i+1] = uint8(s >> 8) b[2*i+1] = uint8(s >> 8)
} }
d.posInBytes += l d.posInBytes += l
if d.posInBytes == total { if d.posInBytes == d.totalBytes {
return l, io.EOF return l, io.EOF
} }
return l, nil return l, nil
@ -119,7 +127,7 @@ func decode(in audio.ReadSeekCloser) (*decoded, int, int, error) {
return nil, 0, 0, err return nil, 0, 0, err
} }
d := &decoded{ d := &decoded{
data: make([]float32, 0, r.Length()), data: make([]float32, r.Length()*2),
totalBytes: int(r.Length()) * 4, // TODO: What if length is 0? totalBytes: int(r.Length()) * 4, // TODO: What if length is 0?
posInBytes: 0, posInBytes: 0,
source: in, source: in,