DSP (File Format): Difference between revisions
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| '''ADPCM nibble count''' | | '''ADPCM nibble count'''; includes frame headers | ||
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| 0x8 | | 0x8 | ||
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== ADPCM Data == | == ADPCM Data == | ||
The ADPCM audio data is split up into multiple ''frames''. Each frame is 8 bytes; it starts with a one-byte header, then has 7 bytes (or 14 samples) of audio data. For each frame, the bottom 4 bits are the scale value, and the top 4 bits are the coefficient index to use for the current frame. | The ADPCM audio data is split up into multiple ''frames''. Each frame is 8 bytes; it starts with a one-byte header, then has 7 bytes (or 14 samples) of audio data. For each frame header, the bottom 4 bits are the scale value, and the top 4 bits are the coefficient index to use for the current frame. | ||
=== Example C Decoding Function === | === Example C Decoding Function === | ||
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u16 scale = 1 << (header & 0xF); | u16 scale = 1 << (header & 0xF); | ||
u8 coef_index = (header >> 4); | u8 coef_index = (header >> 4); | ||
s16 coef1 = d.coefs[coef_index | s16 coef1 = d.coefs[coef_index][0]; | ||
s16 coef2 = d.coefs[coef_index | s16 coef2 = d.coefs[coef_index][1]; | ||
// 7 bytes per frame | // 7 bytes per frame | ||