mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-12-25 03:08:54 +01:00
200 lines
4.8 KiB
Go
200 lines
4.8 KiB
Go
// Copyright 2015 Hajime Hoshi
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package vorbis provides Ogg/Vorbis decoder.
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package vorbis
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import (
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"fmt"
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"io"
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"runtime"
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"github.com/hajimehoshi/ebiten/audio"
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"github.com/hajimehoshi/ebiten/audio/internal/convert"
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"github.com/jfreymuth/oggvorbis"
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)
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// Stream is a decoded audio stream.
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type Stream struct {
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decoded audio.ReadSeekCloser
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size int64
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}
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// Read is implementation of io.Reader's Read.
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func (s *Stream) Read(p []byte) (int, error) {
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return s.decoded.Read(p)
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}
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// Seek is implementation of io.Seeker's Seek.
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//
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// Note that Seek can take long since decoding is a relatively heavy task.
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func (s *Stream) Seek(offset int64, whence int) (int64, error) {
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return s.decoded.Seek(offset, whence)
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}
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// Read is implementation of io.Closer's Close.
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func (s *Stream) Close() error {
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return s.decoded.Close()
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}
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// Size returns the size of decoded stream in bytes.
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func (s *Stream) Size() int64 {
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return s.size
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}
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type decoded struct {
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data []float32
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totalBytes int
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readBytes int
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posInBytes int
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source io.Closer
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decoder *oggvorbis.Reader
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}
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func (d *decoded) readUntil(posInBytes int) error {
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c := 0
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buffer := make([]float32, 8192)
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for d.readBytes < posInBytes {
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n, err := d.decoder.Read(buffer)
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if n > 0 {
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// Actual read bytes might exceed the total bytes.
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if d.readBytes+n*2 > d.totalBytes {
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n = (d.totalBytes - d.readBytes) / 2
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}
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p := d.readBytes / 2
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for i := 0; i < n; i++ {
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d.data[p+i] = buffer[i]
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}
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d.readBytes += n * 2
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}
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if err == io.EOF {
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if err := d.source.Close(); err != nil {
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return err
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}
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break
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}
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if err != nil {
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return err
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}
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c++
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if c%2 == 0 {
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runtime.Gosched()
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}
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}
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return nil
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}
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func (d *decoded) Read(b []uint8) (int, error) {
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l := d.totalBytes - d.posInBytes
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if l > len(b) {
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l = len(b)
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}
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if l < 0 {
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return 0, io.EOF
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}
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// l must be even so that d.posInBytes is always even.
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l = l / 2 * 2
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if err := d.readUntil(d.posInBytes + l); err != nil {
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return 0, err
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}
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for i := 0; i < l/2; i++ {
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f := d.data[d.posInBytes/2+i]
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s := int16(f * (1<<15 - 1))
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b[2*i] = uint8(s)
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b[2*i+1] = uint8(s >> 8)
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}
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d.posInBytes += l
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if d.posInBytes == d.totalBytes {
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return l, io.EOF
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}
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return l, nil
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}
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func (d *decoded) Seek(offset int64, whence int) (int64, error) {
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next := int64(0)
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switch whence {
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case io.SeekStart:
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next = offset
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case io.SeekCurrent:
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next = int64(d.posInBytes) + offset
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case io.SeekEnd:
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next = int64(d.totalBytes) + offset
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}
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// pos should be always even
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next = next / 2 * 2
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d.posInBytes = int(next)
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if err := d.readUntil(d.posInBytes); err != nil {
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return 0, err
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}
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return next, nil
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}
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func (d *decoded) Close() error {
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runtime.SetFinalizer(d, nil)
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return nil
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}
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func (d *decoded) Size() int64 {
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return int64(d.totalBytes)
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}
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// decode accepts an ogg stream and returns a decorded stream.
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func decode(in audio.ReadSeekCloser) (*decoded, int, int, error) {
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r, err := oggvorbis.NewReader(in)
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if err != nil {
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return nil, 0, 0, err
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}
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d := &decoded{
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data: make([]float32, r.Length()*2),
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totalBytes: int(r.Length()) * 4, // TODO: What if length is 0?
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posInBytes: 0,
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source: in,
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decoder: r,
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}
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runtime.SetFinalizer(d, (*decoded).Close)
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if _, err := d.Read(make([]uint8, 65536)); err != nil {
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return nil, 0, 0, err
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}
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if _, err := d.Seek(0, io.SeekStart); err != nil {
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return nil, 0, 0, err
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}
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return d, r.Channels(), r.SampleRate(), nil
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}
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// Decode decodes Ogg/Vorbis data to playable stream.
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//
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// Decode returns error when the source format is wrong.
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//
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// Sample rate is automatically adjusted to fit with the audio context.
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func Decode(context *audio.Context, src audio.ReadSeekCloser) (*Stream, error) {
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decoded, channelNum, sampleRate, err := decode(src)
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if err != nil {
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return nil, err
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}
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if channelNum != 1 && channelNum != 2 {
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return nil, fmt.Errorf("vorbis: number of channels must be 1 or 2 but was %d", channelNum)
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}
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var s audio.ReadSeekCloser = decoded
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size := decoded.Size()
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if channelNum == 1 {
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s = convert.NewStereo16(s, true, false)
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size *= 2
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}
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if sampleRate != context.SampleRate() {
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s = convert.NewResampling(s, size, sampleRate, context.SampleRate())
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size = size * int64(context.SampleRate()) / int64(sampleRate)
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}
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return &Stream{decoded: s, size: size}, nil
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}
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