ebiten/audio/internal/convert/resampling_test.go
2018-01-09 00:26:54 +09:00

90 lines
2.2 KiB
Go

// Copyright 2018 The Ebiten Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package convert_test
import (
"io/ioutil"
"math"
"testing"
"github.com/hajimehoshi/ebiten/audio"
. "github.com/hajimehoshi/ebiten/audio/internal/convert"
)
func soundAt(timeInSecond float64) float64 {
const freq = 220
amp := []float64{1.0, 0.8, 0.6, 0.4, 0.2}
v := 0.0
for j := 0; j < len(amp); j++ {
v += amp[j] * math.Sin(2.0*math.Pi*timeInSecond*freq*float64(j+1))
}
if v > 1 {
v = 1
}
if v < -1 {
v = -1
}
return v
}
func newSoundBytes(sampleRate int) []byte {
b := make([]byte, sampleRate*4) // 1 second
for i := 0; i < len(b)/4; i++ {
v := soundAt(float64(i) / float64(sampleRate))
v16 := int16(v * (1<<15 - 1))
b[4*i] = byte(v16)
b[4*i+1] = byte(v16 >> 8)
b[4*i+2] = byte(v16)
b[4*i+3] = byte(v16 >> 8)
}
return b
}
func TestResampling(t *testing.T) {
cases := []struct {
In int
Out int
}{
{
In: 44100,
Out: 48000,
},
{
In: 48000,
Out: 44100,
},
}
for _, c := range cases {
inB := newSoundBytes(c.In)
outS := NewResampling(audio.BytesReadSeekCloser(inB), int64(len(inB)), c.In, c.Out)
gotB, err := ioutil.ReadAll(outS)
if err != nil {
t.Fatal(err)
}
wantB := newSoundBytes(c.Out)
if len(gotB) != len(wantB) {
t.Errorf("len(gotB) == %d but len(wantB) == %d", len(gotB), len(wantB))
}
for i := 0; i < len(gotB)/2; i++ {
got := float64(int16(gotB[2*i])|(int16(gotB[2*i+1])<<8)) / (1<<15 - 1)
want := float64(int16(wantB[2*i])|(int16(wantB[2*i+1])<<8)) / (1<<15 - 1)
if math.Abs(got-want) > 0.025 {
t.Errorf("sample rate: %d, index: %d: got: %f, want: %f", c.Out, i, got, want)
}
}
}
}