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neotools: make adpcmb decoder work on nibble pairs like adpcma

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a dinosaur
2023-12-29 03:39:33 +11:00
parent 70bbf3d0d1
commit 5b28c18472
2 changed files with 3 additions and 11 deletions
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12
neotools/adpcmb.c
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@@ -79,15 +79,13 @@ void adpcmBDecoderInit(AdpcmBDecoderState* decoder)
{ {
decoder->xn = 0; decoder->xn = 0;
decoder->stepSize = 127; decoder->stepSize = 127;
decoder->shift = 4;
decoder->step = 0;
} }
void adpcmBDecode(AdpcmBDecoderState* decoder, const uint8_t* restrict in, int16_t* restrict out, int len) void adpcmBDecode(AdpcmBDecoderState* decoder, const uint8_t* restrict in, int16_t* restrict out, int len)
{ {
for (int lpc = 0; lpc < len; ++lpc) for (long lpc = 0; lpc < len * 2; ++lpc)
{ {
uint8_t adpcm = (*in >> decoder->shift) & 0xF; uint8_t adpcm = (!(lpc & 0x1) ? (*in) >> 4 : (*in++)) & 0xF;
long i = ((adpcm & 7) * 2 + 1) * decoder->stepSize / 8; long i = ((adpcm & 7) * 2 + 1) * decoder->stepSize / 8;
if (adpcm & 8) if (adpcm & 8)
@@ -100,10 +98,6 @@ void adpcmBDecode(AdpcmBDecoderState* decoder, const uint8_t* restrict in, int16
decoder->stepSize = CLAMP(decoder->stepSize, 127, 24576); decoder->stepSize = CLAMP(decoder->stepSize, 127, 24576);
(*out++) = (int16_t)decoder->xn; (*out++) = (int16_t)decoder->xn;
in += decoder->step;
decoder->step = decoder->step ^ 1;
decoder->shift = decoder->shift ^ 4;
} }
} }
@@ -158,7 +152,7 @@ static int decode(const char* inPath, const char* outPath, uint32_t sampleRate)
{ {
if ((read = fread(adpcmData, 1, BUFFER_SIZE, inFile)) > 0) if ((read = fread(adpcmData, 1, BUFFER_SIZE, inFile)) > 0)
{ {
adpcmBDecode(&decoder, adpcmData, wavData, read * 2); adpcmBDecode(&decoder, adpcmData, wavData, read);
fwrite(wavData, sizeof(int16_t), read * 2, outFile); fwrite(wavData, sizeof(int16_t), read * 2, outFile);
} }
} }

2
neotools/adpcmb.h
View File

@@ -16,9 +16,7 @@ void adpcmBEncode(AdpcmBEncoderState* encoder, const int16_t* restrict in, uint8
typedef struct AdpcmBDecoderState typedef struct AdpcmBDecoderState
{ {
int shift, step;
long xn, stepSize; long xn, stepSize;
} AdpcmBDecoderState; } AdpcmBDecoderState;
void adpcmBDecoderInit(AdpcmBDecoderState* decoder); void adpcmBDecoderInit(AdpcmBDecoderState* decoder);