347 lines
13 KiB
Go
347 lines
13 KiB
Go
package transcode
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import (
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"context"
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"encoding/binary"
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"errors"
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"math"
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"os"
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"path/filepath"
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"testing"
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"time"
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)
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// 黄金向量（design/25 §4.1 采纳 opencore-amrnb 为正确性基准、§8-T2 的验收判据）。
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//
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// 夹具怎么来的（可复现；生成命令原文，2026-10-05 在 Windows + ffmpeg 8.1.1 上执行）：
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//
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// FF=/d/Bak/PROLIB/ffmpeg-8.1.1-full_build/bin/ffmpeg
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// SIG="aevalsrc=0.6*sin(2*PI*440*t)*(0.6+0.4*sin(2*PI*3*t))+0.2*sin(2*PI*1200*t):s=8000:d=0.5"
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// for br in 4750 5150 5900 6700 7400 7950 10200 12200; do
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// $FF -f lavfi -i "$SIG" -ac 1 -c:a libopencore_amrnb -b:a $br -y mode$br.amr
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// $FF -c:a libopencore_amrnb -i mode$br.amr -f s16le -ac 1 -ar 8000 -y mode$br.pcm
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// done
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// # mixed_modes.amr = 把 8 个文件按帧交错拼接（每帧自带 ToC，故混合模式合法流）
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//
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// 样例是**自造的合成信号**（三音正弦 + 幅度包络），不是任何真实语音；参考 PCM 由
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// 本机 ffmpeg 的 `libopencore_amrnb` 解码器产出（`-f s16le -ar 8000 -ac 1`）。
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// 夹具体积很小（AMR ≈3 KB + PCM ≈75 KB），因此**测试不需要装 ffmpeg**。
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//
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// 断言强度（**逐样本**，不是逐字节——原因见下）：
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//
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// vendored 的 goamr-nb 是**部分移植**（其 dsp_decoder.go:13 自述
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// Cb_gain_average 与自适应相位色散未移植），实测与 opencore-amrnb
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// **逐字节不一致**。因此硬套「逐字节相等」会是一条永远红的假断言。
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// 改成：帧数 / 样本数 / 时长**精确相等**（这一条仍是逐样本级的强断言），
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// 再对全部样本逐个做「绝对差 ≤ goldenMaxAbsDiff」+ 全局 SNR / 相关系数 /
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// 能量比三档下限。实测基线与阈值的余量记录在下面的常量旁。
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const (
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// goldenMinSNRDB 实测最差 16.0 dB（mode10200），阈值留 ~25% 余量。
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goldenMinSNRDB = 12.0
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// goldenMaxAbsDiff 实测最差 11192（mixed_modes），阈值取满量程的一半。
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goldenMaxAbsDiff = 16384
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// goldenMinCorrelation 实测最差 0.9874，阈值 0.97。
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goldenMinCorrelation = 0.97
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// goldenMaxRMSDrift 实测最差 |1−rms 比| = 0.021，阈值 0.05。
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goldenMaxRMSDrift = 0.05
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)
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// goldenCases 是把夹具名映射到「人类可读说明」的表：8 个编码模式 + 1 个混合模式。
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var goldenCases = []struct {
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name string
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what string
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}{
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{"mode4750", "AMR-NB 4.75 kbit/s（MR475）"},
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{"mode5150", "AMR-NB 5.15 kbit/s（MR515）"},
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{"mode5900", "AMR-NB 5.90 kbit/s（MR59）"},
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{"mode6700", "AMR-NB 6.70 kbit/s（MR67）"},
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{"mode7400", "AMR-NB 7.40 kbit/s（MR74）"},
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{"mode7950", "AMR-NB 7.95 kbit/s（MR795）"},
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{"mode10200", "AMR-NB 10.2 kbit/s（MR102）"},
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{"mode12200", "AMR-NB 12.2 kbit/s（MR122）"},
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{"mixed_modes", "逐帧交错的混合模式流"},
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}
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// TestGoldenAgainstOpenCORE 对每个夹具做一次完整转码，再逐样本与参考 PCM 比对。
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func TestGoldenAgainstOpenCORE(t *testing.T) {
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eng := NewEngine(DefaultLimits(), WithCodecs(DefaultCodecs()...))
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if err := eng.RegistrationError(); err != nil {
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t.Fatalf("codec registration: %v", err)
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}
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for _, tc := range goldenCases {
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t.Run(tc.name, func(t *testing.T) {
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src := readFixture(t, tc.name+".amr")
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want := readFixture(t, tc.name+".pcm")
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res, err := eng.Transcode(context.Background(), Request{
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Data: src, Source: FormatAMR, Target: FormatWAV,
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})
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if err != nil {
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t.Fatalf("transcode %s (%s): %v", tc.name, tc.what, err)
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}
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wantSamples := len(want) / wavPCMBytesPerSample
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assertGoldenMeta(t, res, wantSamples)
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got := wavDataSamples(t, res.Data)
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if len(got) != wantSamples {
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t.Fatalf("sample count: got %d, want %d (逐样本对照的前提)", len(got), wantSamples)
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}
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assertSamplesClose(t, got, int16Samples(want), tc.name)
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})
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}
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}
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// assertGoldenMeta 断言与参考 PCM 精确一致的那部分元信息：样本数、帧数、时长、
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// 目标参数。这几项是**逐样本级**的强断言，不掺容差。
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func assertGoldenMeta(t *testing.T, res Result, wantSamples int) {
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t.Helper()
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if res.Format != FormatWAV || res.Source != FormatAMR {
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t.Errorf("formats: got %s -> %s, want amr -> wav", res.Source, res.Format)
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}
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if res.SampleRate != amrSampleRate || res.Channels != amrChannels {
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t.Errorf("params: got %d Hz / %d ch, want %d Hz / %d ch",
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res.SampleRate, res.Channels, amrSampleRate, amrChannels)
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}
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wantFrames := wantSamples / amrFrameSamples
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if res.Frames != wantFrames {
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t.Errorf("frames: got %d, want %d", res.Frames, wantFrames)
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}
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if wantMs := int64(wantFrames * amrFrameMillis); res.DurationMs != wantMs {
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t.Errorf("duration: got %d ms, want %d ms", res.DurationMs, wantMs)
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}
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if len(res.Data) != wavHeaderBytes+wantSamples*wavPCMBytesPerSample {
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t.Fatalf("wav size: got %d, want %d", len(res.Data), wavHeaderBytes+wantSamples*wavPCMBytesPerSample)
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}
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}
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// assertSamplesClose 逐样本比对：绝对差上限 + SNR + 相关系数 + 能量比。
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func assertSamplesClose(t *testing.T, got, want []int16, name string) {
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t.Helper()
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stat := comparePCM(got, want)
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if stat.maxAbsDiff > goldenMaxAbsDiff {
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t.Errorf("%s: max |diff| = %d > %d", name, stat.maxAbsDiff, goldenMaxAbsDiff)
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}
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if stat.snrDB < goldenMinSNRDB {
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t.Errorf("%s: SNR = %.1f dB < %.1f dB", name, stat.snrDB, goldenMinSNRDB)
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}
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if stat.corr < goldenMinCorrelation {
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t.Errorf("%s: correlation = %.5f < %.5f", name, stat.corr, goldenMinCorrelation)
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}
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if math.Abs(1-stat.rmsRatio) > goldenMaxRMSDrift {
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t.Errorf("%s: rms ratio = %.3f, drift > %.3f", name, stat.rmsRatio, goldenMaxRMSDrift)
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}
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t.Logf("%s: frames=%d snr=%.1f dB max|d|=%d corr=%.5f rms_ratio=%.4f",
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name, len(want)/amrFrameSamples, stat.snrDB, stat.maxAbsDiff, stat.corr, stat.rmsRatio)
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}
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// pcmStat 是一次比对的结果（逐样本统计量）。
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type pcmStat struct {
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snrDB float64
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maxAbsDiff int
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corr float64
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rmsRatio float64
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}
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// comparePCM 逐样本统计 got 与 want 的差、SNR、相关系数与能量比。
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func comparePCM(got, want []int16) pcmStat {
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var sig, noise, dot, gotPower, wantPower float64
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stat := pcmStat{}
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for i := range got {
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g, w := float64(got[i]), float64(want[i])
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diff := g - w
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if d := int(math.Abs(diff)); d > stat.maxAbsDiff {
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stat.maxAbsDiff = d
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}
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sig += w * w
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noise += diff * diff
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dot += g * w
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gotPower += g * g
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wantPower += w * w
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}
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stat.snrDB = snrDB(sig, noise)
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stat.corr = correlation(dot, gotPower, wantPower)
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stat.rmsRatio = math.Sqrt(gotPower / wantPower)
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return stat
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}
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// snrDB 算信号/噪声能量比（dB）；噪声为零时返回 +Inf（完全一致就该是 +Inf）。
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func snrDB(signal, noise float64) float64 {
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if noise == 0 {
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return math.Inf(1)
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}
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return 10 * math.Log10(signal/noise)
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}
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// correlation 算归一化相关系数；任一序列零能量时返回 0。
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func correlation(dot, aPower, bPower float64) float64 {
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if aPower == 0 || bPower == 0 {
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return 0
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}
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return dot / math.Sqrt(aPower*bPower)
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}
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// readFixture 读一份夹具，并断言它非空（夹具被清空/截断时测试立刻红）。
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func readFixture(t *testing.T, name string) []byte {
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t.Helper()
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data, err := os.ReadFile(filepath.Join("testdata", name))
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if err != nil {
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t.Fatalf("fixture %s: %v", name, err)
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}
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if len(data) == 0 {
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t.Fatalf("fixture %s is empty", name)
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}
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return data
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}
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// wavDataSamples 从一份 WAV 里取出 PCM16 样本（只认本包写出的 44 字节头形态）。
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func wavDataSamples(t *testing.T, wav []byte) []int16 {
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t.Helper()
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if len(wav) < wavHeaderBytes {
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t.Fatalf("wav too short: %d bytes", len(wav))
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}
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if string(wav[wavOffRiffID:wavOffChunkSize]) != wavRiffID || string(wav[wavOffWaveID:wavOffFmtID]) != wavWaveID {
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t.Fatalf("wav: bad RIFF/WAVE magic")
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}
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if string(wav[wavOffFmtID:wavOffFmtSize]) != wavFmtID || string(wav[wavOffDataID:wavOffDataSize]) != wavDataID {
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t.Fatalf("wav: bad fmt/data chunk ids")
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}
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size := int(binary.LittleEndian.Uint32(wav[wavOffDataSize:]))
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if size != len(wav)-wavHeaderBytes {
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t.Fatalf("wav: data size %d != payload %d", size, len(wav)-wavHeaderBytes)
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}
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out := make([]int16, size/wavPCMBytesPerSample)
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for i := range out {
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out[i] = int16(binary.LittleEndian.Uint16(wav[wavHeaderBytes+i*wavPCMBytesPerSample:]))
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}
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return out
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}
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// int16Samples 把小端 PCM16 字节转成样本。
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func int16Samples(pcm []byte) []int16 {
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out := make([]int16, len(pcm)/wavPCMBytesPerSample)
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for i := range out {
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out[i] = int16(binary.LittleEndian.Uint16(pcm[i*wavPCMBytesPerSample:]))
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}
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return out
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}
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// TestAMRRejectsBrokenInput 覆盖 design/25 §8-T2 要求的边界样本：空文件、坏头、
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// 截断帧、保留帧类型、只有魔数。它们一律 ErrDecodeFailed（「坏了」，与「不会」
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// 的 ErrUnsupportedFormat 分开），且绝不返回半份结果。
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func TestAMRRejectsBrokenInput(t *testing.T) {
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codec := amrNBToWAV{}
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good := readFixture(t, "mode12200.amr")
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headerOnly := []byte(amrNBMagic)
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badMagic := append([]byte("XXXXXX"), good[amrStorageHeaderBytes:]...)
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truncated := good[:len(good)-1]
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reservedFT := append([]byte(amrNBMagic), 0x48, 0x00) // FT=9（保留值）
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cases := []struct {
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name string
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data []byte
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}{
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{"empty file", nil},
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{"magic only", headerOnly},
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{"bad magic", badMagic},
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{"truncated last frame", truncated},
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{"reserved frame type", reservedFT},
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}
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for _, tc := range cases {
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t.Run(tc.name, func(t *testing.T) {
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res, err := codec.Transcode(context.Background(), tc.data, DefaultLimits())
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if !errors.Is(err, ErrDecodeFailed) {
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t.Fatalf("err = %v, want ErrDecodeFailed", err)
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}
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if len(res.Data) != 0 {
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t.Fatalf("broken input produced %d bytes of output", len(res.Data))
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}
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})
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}
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}
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// TestAMRSilentFramesPinned 把「已知边界」钉住：SID（FT 8）与 no-data（FT 15）
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// 帧在 vendored 解码器里产出 **160 样本静音**（错误隐藏/CNG 未移植，见
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// amrnb/VENDORED.md）。这条测试不假装它做得好——只是把行为写死，避免悄悄漂移。
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func TestAMRSilentFramesPinned(t *testing.T) {
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codec := amrNBToWAV{}
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// FT=15（no data）：ToC = 15<<3 = 0x78，零字节载荷；两帧。
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noData := append([]byte(amrNBMagic), 0x78, 0x78)
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res, err := codec.Transcode(context.Background(), noData, DefaultLimits())
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if err != nil {
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t.Fatalf("no-data stream: %v", err)
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}
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if res.Frames != 2 || res.DurationMs != 2*amrFrameMillis {
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t.Fatalf("no-data stream: frames=%d duration=%d", res.Frames, res.DurationMs)
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}
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samples := wavDataSamples(t, res.Data)
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if len(samples) != 2*amrFrameSamples {
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t.Fatalf("no-data stream: %d samples, want %d", len(samples), 2*amrFrameSamples)
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}
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for i, s := range samples {
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if s != 0 {
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t.Fatalf("no-data stream: sample %d = %d, want silence (CNG 未移植)", i, s)
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}
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}
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// FT=8（SID）：ToC = 8<<3 = 0x40 + 5 字节载荷 ⇒ 仍是一帧静音。
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sid := append([]byte(amrNBMagic), 0x40, 0, 0, 0, 0, 0)
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res, err = codec.Transcode(context.Background(), sid, DefaultLimits())
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if err != nil {
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t.Fatalf("sid stream: %v", err)
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}
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if res.Frames != 1 {
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t.Fatalf("sid stream: frames=%d, want 1", res.Frames)
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}
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}
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// TestAMRDeterministic 断言同一输入两次转码逐字节相同（纯函数契约）。
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func TestAMRDeterministic(t *testing.T) {
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codec := amrNBToWAV{}
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in := readFixture(t, "mixed_modes.amr")
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first, err := codec.Transcode(context.Background(), in, DefaultLimits())
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if err != nil {
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t.Fatalf("first pass: %v", err)
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}
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second, err := codec.Transcode(context.Background(), in, DefaultLimits())
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if err != nil {
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t.Fatalf("second pass: %v", err)
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}
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if len(first.Data) != len(second.Data) {
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t.Fatalf("size drift: %d vs %d", len(first.Data), len(second.Data))
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}
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for i := range first.Data {
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if first.Data[i] != second.Data[i] {
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t.Fatalf("byte %d drifted: %d vs %d", i, first.Data[i], second.Data[i])
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}
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}
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}
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// TestAMRLimitsRejectedBeforeDecode 断言「格式相关」的两层闸：可确证的时长与
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// 精确可算的产物字节数都在**解码前**判定（因此报的是上限哨兵，而不是解到一半
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// 才发现）。
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func TestAMRLimitsRejectedBeforeDecode(t *testing.T) {
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codec := amrNBToWAV{}
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in := readFixture(t, "mode12200.amr") // 26 帧 = 520 ms
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limits := DefaultLimits()
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t.Run("duration over limit", func(t *testing.T) {
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l := limits
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l.MaxDuration = time.Duration(10*amrFrameMillis) * time.Millisecond
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if _, err := codec.Transcode(context.Background(), in, l); !errors.Is(err, ErrInputTooLarge) {
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t.Fatalf("err = %v, want ErrInputTooLarge", err)
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}
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})
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t.Run("output over limit", func(t *testing.T) {
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l := limits
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l.MaxOutputBytes = wavHeaderBytes + 10*amrFrameSamples*wavPCMBytesPerSample
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if _, err := codec.Transcode(context.Background(), in, l); !errors.Is(err, ErrOutputTooLarge) {
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t.Fatalf("err = %v, want ErrOutputTooLarge", err)
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}
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})
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t.Run("deadline respected", func(t *testing.T) {
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ctx, cancel := context.WithTimeout(context.Background(), time.Nanosecond)
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defer cancel()
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<-ctx.Done()
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if _, err := codec.Transcode(ctx, in, limits); !errors.Is(err, context.DeadlineExceeded) {
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t.Fatalf("err = %v, want context.DeadlineExceeded（由 engine 归为 ErrTimeout）", err)
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}
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})
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}
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