mirror of
https://github.com/hajimehoshi/ebiten.git
synced 2024-09-20 05:12:18 +02:00
117 lines
2.3 KiB
Go
117 lines
2.3 KiB
Go
// Copyright 2017 The Ebiten Authors
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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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// +build !js
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package mp3
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import (
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"errors"
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"io"
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)
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var (
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reader io.Reader
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readerCache []uint8
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readerPos int
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readerEOF bool
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)
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func (f *frame) numberOfChannels() int {
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if f.header.mode == mpeg1ModeSingleChannel {
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return 1
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}
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return 2
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}
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func (f *frame) decodeL3() []uint8 {
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out := make([]uint8, 576*4*2)
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nch := f.numberOfChannels()
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for gr := 0; gr < 2; gr++ {
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for ch := 0; ch < nch; ch++ {
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f.l3Requantize(gr, ch)
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// Reorder short blocks
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f.l3Reorder(gr, ch)
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}
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f.l3Stereo(gr)
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for ch := 0; ch < nch; ch++ {
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f.l3Antialias(gr, ch)
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// (IMDCT,windowing,overlapp add)
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f.l3HybridSynthesis(gr, ch)
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f.l3FrequencyInversion(gr, ch)
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// Polyphase subband synthesis
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f.l3SubbandSynthesis(gr, ch, out[576*4*gr:])
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}
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}
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return out
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}
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func getByte() (uint8, error) {
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for len(readerCache) == 0 && !readerEOF {
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buf := make([]uint8, 4096)
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n, err := reader.Read(buf)
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readerCache = append(readerCache, buf[:n]...)
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if err != nil {
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if err == io.EOF {
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readerEOF = true
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} else {
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return 0, err
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}
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}
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}
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if len(readerCache) == 0 {
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return 0, io.EOF
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}
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b := readerCache[0]
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readerCache = readerCache[1:]
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readerPos++
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return b, nil
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}
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func getBytes(buf []int) (int, error) {
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for i := range buf {
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v, err := getByte()
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buf[i] = int(v)
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if err == io.EOF {
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return i, io.EOF
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}
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}
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return len(buf), nil
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}
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func getFilepos() int {
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return readerPos
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}
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var eof = errors.New("mp3: expected EOF")
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func decode(r io.Reader, w io.Writer) error {
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reader = r
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for {
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f, err := readFrame()
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if err == nil {
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out := f.decodeL3()
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if _, err := w.Write(out); err != nil {
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return err
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}
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continue
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}
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if err == eof {
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break
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}
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return err
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}
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return nil
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}
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