Salamander-Music-
Salam Player | 蝾螈播放器
针对本地、远程数据而生的超棒的播放器App | A great music player app designed for both local and remote data.
基于底层AudioTrack开发的音频API，拥有独立的DSP算法，能够做到低延迟的同时尽可能地输出高质量音频
最新版本 | Latest Release
关于音频处理：
Salamander Player（Salam Player）将以AudioTrack为底层基础进行研发的音频API系统（Salam API）：
音频入口：
使用了全链路同步低延迟系统 及DSP芯片的读取、处理功能，拥有独立的USB独占处理方式（支持外挂DSP转接及自带DSP芯片处理的有线耳机）
DSP芯片读取示例：
public interface UsbProbeCallback {
void onReady(String chipVendor, String productName, String headphoneMaker, int vendorId, int productId, String serial);
}
public static final class UsbDspMeta {
public static volatile String chipVendor = "";
public static volatile String productName = "";
public static volatile String headphoneMaker = "";
public static volatile int vendorId = 0;
public static volatile int productId = 0;
public static volatile String serial = "";
}
public static String getUsbChipVendor() { return UsbDspMeta.chipVendor; }
public static String getUsbProductName() { return UsbDspMeta.productName; }
public static String getUsbHeadphoneMaker() { return UsbDspMeta.headphoneMaker; }
public static int getUsbVendorId() { return UsbDspMeta.vendorId; }
public static int getUsbProductId() { return UsbDspMeta.productId; }
public static String getUsbSerial() { return UsbDspMeta.serial; }
private static String nz(@Nullable String s, String def) { return (s == null || s.isEmpty()) ? def : s; }
@Nullable
private static String readUsbStringDesc(UsbAudioDspSession s, int index) {
if (index <= 0) return null;
byte[] buf = new byte[255];
int wValue = (0x03 << 8) | (index & 0xFF);
int r = s.controlIn(0x80, 0x06, wValue, 0x0409, buf, 200);
if (r >= 2 && (buf[1] & 0xFF) == 0x03) {
int len = Math.min(r, buf[0] & 0xFF);
if (len > 2) {
try { return new String(buf, 2, len - 2, "UTF-16LE"); } catch (Exception ignore) {}
}
}
return null;
}
音频处理：
Salam API拥有独立的DSP处理入口，在设备性能支持的情况下，可接入无数个DSP处理器。其中包括低频增强、虚拟低频、HRTF环绕等核心算法
算法示例（以IIR为例）：
public byte[] process(byte[] pcmData) {
try {
short[] s = new short[pcmData.length / 2];
ByteBuffer.wrap(pcmData).order(ByteOrder.LITTLE_ENDIAN).asShortBuffer().get(s);
final int frames = s.length / 2;
final int BLOCK = 192; // 防抖
for (int base = 0; base < frames; base += BLOCK) {
int end = Math.min(base + BLOCK, frames);
int count = end - base;
// —— RMS ——
float sum = 0f;
for (int n = 0; n < count; n++) {
int i = (base + n) * 2;
float L = s[i] / 32768f;
float R = s[i + 1] / 32768f;
float a = 0.5f * (Math.abs(L) + Math.abs(R));
sum += a * a;
}
float rms = (float)Math.sqrt(sum / Math.max(1, count));
rmsEnv += rmsCoef * (rms - rmsEnv);
// —— 动态低搁架 ——
float t = clamp((loudnessRef - rmsEnv) / loudnessRange, 0f, 1f);
t = t * t * (3f - 2f * t); // Smooth Step
float dynDb = lsBaseDb + (enableLoudness ? (loudnessStrength * (3.5f - lsBaseDb) * t) : 0f);
dynDb = clamp(dynDb, -20f, 20f);
if (Math.abs(dynDb - lastLsDb) > 0.1f) {
updateLowShelf(dynDb);
lastLsDb = dynDb;
}
// —— 处理块 —— //
for (int n = 0; n < count; n++) {
int i = (base + n) * 2;
float L = s[i] / 32768f;
float R = s[i + 1] / 32768f;
// IIR EQ
L = hpL.process(L); R = hpR.process(R);
L = lsL.process(L); R = lsR.process(R);
L = lmidL.process(L); R = lmidR.process(R);
L = midDipL.process(L); R = midDipR.process(R);
L = upMidDipL.process(L); R = upMidDipR.process(R);
L = hsL.process(L); R = hsR.process(R);
// ======= peaking cut =======
for (int k = 0; k < highlights.size(); k++) {
HighlightBand hb = highlights.get(k);
if (hb.isCutMode) {
L = hb.peakL.process(L);
R = hb.peakR.process(R);
} else {
L = hb.lsNegL.process(L);
R = hb.lsNegR.process(R);
L = hb.peakPosL.process(L);
R = hb.peakPosR.process(R);
L = hb.hsNegL.process(L);
R = hb.hsNegR.process(R);
}
}
// 末端限幅
float peak = Math.max(Math.abs(L), Math.abs(R));
limEnv += ((peak > limEnv) ? limAtkCoef : limRelCoef) * (peak - limEnv);
float targetGain = (limEnv > LIM_CEIL) ? (LIM_CEIL / (limEnv + 1e-9f)) : 1.0f;
float gCoef = (targetGain < limGain) ? limAtkCoef : limRelCoef;
limGain += gCoef * (targetGain - limGain);
L *= limGain; R *= limGain;
L = softClip(L); R = softClip(R);
s[i] = toShort(L);
s[i + 1] = toShort(R);
}
}
ByteBuffer.wrap(pcmData).order(ByteOrder.LITTLE_ENDIAN).asShortBuffer().put(s);
return pcmData;
} catch (Exception e) {
Log.e(TAG, "SpeakerFRShaper error: " + e.getMessage());
return pcmData;
}
}
关于UI设计：
Salam Player全界面使用了现代化排布，使用了全动态UI效果
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