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Fixed false-detection of MP3 headers #4

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Fixed false-detection of MP3 headers #4

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84 changes: 52 additions & 32 deletions src/main/java/fr/delthas/javamp3/Decoder.java
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Original file line number Diff line number Diff line change
Expand Up @@ -432,7 +432,17 @@ public static SoundData init(InputStream in) throws IOException {
return null;
return soundData;
}


private static boolean isHeaderValid(int id, int layer, int protectionBit, int bitrateIndex, int samplingFrequency, int paddingBit,
int privateBit, int mode, int modeExtension, int copyright, int original, int emphasis) {
if (id == 1) return false;
if (layer < 1 || layer > 3) return false;
if (bitrateIndex < 0 || bitrateIndex > 14) return false;
if (samplingFrequency < 0 || samplingFrequency > 2) return false;
if (emphasis == 2) return false;
return mode == 1 || modeExtension == 0;
}

public static boolean decodeFrame(SoundData soundData) throws IOException {
if (soundData.buffer.lastByte == -1) {
return false;
Expand All @@ -456,10 +466,10 @@ public static boolean decodeFrame(SoundData soundData) throws IOException {
break;
}
}
soundData.buffer.current = 4;
int id = read(soundData.buffer, 1);

soundData.buffer.current = 3;

int id = read(soundData.buffer, 2);
int layer = read(soundData.buffer, 2);
int protectionBit = read(soundData.buffer, 1);
int bitrateIndex = read(soundData.buffer, 4);
Expand All @@ -468,38 +478,48 @@ public static boolean decodeFrame(SoundData soundData) throws IOException {
int privateBit = read(soundData.buffer, 1);
int mode = read(soundData.buffer, 2);
int modeExtension = read(soundData.buffer, 2);
read(soundData.buffer, 4);

int copyright = read(soundData.buffer, 1);
int original = read(soundData.buffer, 1);
int emphasis = read(soundData.buffer, 2);

if (!isHeaderValid(id, layer, protectionBit, bitrateIndex, samplingFrequency, paddingBit, privateBit, mode, modeExtension, copyright, original, emphasis)) {
return decodeFrame(soundData); // Invalid header
}

if (soundData.frequency == -1) {
soundData.frequency = SAMPLING_FREQUENCY[samplingFrequency];
}

if (soundData.stereo == -1) {
if (mode == 0b11 /* single_channel */) {
soundData.stereo = 0;
} else {
soundData.stereo = 1;
}
if (layer == 0b01 /* layer III */) {
if (mode == 0b11 /* single_channel */) {
soundData.mainData = new byte[1024];
soundData.store = new float[32 * 18];
soundData.v = new float[1024];
soundData.stereo = 0;
} else {
soundData.mainData = new byte[2 * 1024];
soundData.store = new float[2 * 32 * 18];
soundData.v = new float[2 * 1024];
soundData.stereo = 1;
}
soundData.mainDataReader = new MainDataReader(soundData.mainData);
} else {
if (mode == 0b11 /* single_channel */) {
soundData.synthOffset = new int[]{64};
soundData.synthBuffer = new float[1024];
if (layer == 0b01 /* layer III */) {
if (mode == 0b11 /* single_channel */) {
soundData.mainData = new byte[1024];
soundData.store = new float[32 * 18];
soundData.v = new float[1024];
} else {
soundData.mainData = new byte[2 * 1024];
soundData.store = new float[2 * 32 * 18];
soundData.v = new float[2 * 1024];
}
soundData.mainDataReader = new MainDataReader(soundData.mainData);
} else {
soundData.synthOffset = new int[]{64, 64};
soundData.synthBuffer = new float[2 * 1024];
if (mode == 0b11 /* single_channel */) {
soundData.synthOffset = new int[]{64};
soundData.synthBuffer = new float[1024];
} else {
soundData.synthOffset = new int[]{64, 64};
soundData.synthBuffer = new float[2 * 1024];
}
}
} else {
if (soundData.stereo == 0 && mode != 0b11) {
return decodeFrame(soundData); // Invalid header
}
}
}

int bound = modeExtension == 0b0 ? 4 : modeExtension == 0b01 ? 8 : modeExtension == 0b10 ? 12 : modeExtension == 0b11 ? 16 : -1;
Expand Down Expand Up @@ -919,9 +939,9 @@ private static void samples_III(Buffer buffer, int stereo, MainDataReader mainDa

outer:
while (true) {


/* Only reorder short blocks */

/* Only reorder short blocks */
if ((win_switch_flag[ch * 2 + gr] == 1) &&
(block_type[ch * 2 + gr] == 2)) { /* Short blocks */

Expand Down Expand Up @@ -1150,10 +1170,10 @@ private static void samples_III(Buffer buffer, int stereo, MainDataReader mainDa
rawout[p] = sum * IMDCT_WINDOW_LAYER_III[bt * 36 + p];
}
}



/* Overlapp add with stored vector into main_data vector */


/* Overlapp add with stored vector into main_data vector */
for (int i = 0; i < 18; i++) {

is[ch * 2 * 576 + gr * 576 + sb * 18 + i] = rawout[i] + store[ch * 32 * 18 + sb * 18 + i];
Expand Down