diff options
Diffstat (limited to 'tools/aif2pcm/main.c')
| -rw-r--r-- | tools/aif2pcm/main.c | 118 |
1 files changed, 39 insertions, 79 deletions
diff --git a/tools/aif2pcm/main.c b/tools/aif2pcm/main.c index 6eb47ade1..fbb024a1d 100644 --- a/tools/aif2pcm/main.c +++ b/tools/aif2pcm/main.c @@ -23,6 +23,7 @@ #include <string.h> #include <stdbool.h> #include <stdint.h> +#include <limits.h> /* extended.c */ void ieee754_write_extended (double, uint8_t*); @@ -287,7 +288,7 @@ void read_aif(struct Bytes *aif, AifData *aif_data) } // This is a table of deltas between sample values in compressed PCM data. -const int8_t gDeltaEncodingTable[] = { +const int gDeltaEncodingTable[] = { 0, 1, 4, 9, 16, 25, 36, 49, -64, -49, -36, -25, -16, -9, -4, -1, }; @@ -359,6 +360,26 @@ struct Bytes *delta_decompress(struct Bytes *delta, unsigned int expected_length return pcm; } +int get_delta_index(uint8_t sample, uint8_t prev_sample) +{ + int best_error = INT_MAX; + int best_index = -1; + + for (int i = 0; i < 16; i++) + { + uint8_t new_sample = prev_sample + gDeltaEncodingTable[i]; + int error = sample > new_sample ? sample - new_sample : new_sample - sample; + + if (error < best_error) + { + best_error = error; + best_index = i; + } + } + + return best_index; +} + struct Bytes *delta_compress(struct Bytes *pcm) { struct Bytes *delta = malloc(sizeof(struct Bytes)); @@ -384,103 +405,42 @@ struct Bytes *delta_compress(struct Bytes *pcm) delta->data = malloc(delta->length + 33); - uint8_t hi, lo; unsigned int i = 0; unsigned int j = 0; int k; - int l; - int8_t base; - int8_t diff; + uint8_t base; + int delta_index; + while (i < pcm->length) { - base = (int8_t)pcm->data[i++]; - delta->data[j++] = (uint8_t)base; - if (i >= pcm->length) - { - break; - } - hi = 0; - diff = ((int8_t)pcm->data[i++]) - base; - if (diff > 49) diff = 49; - if (diff < -64) diff = -64; - if (diff < 0) - { - for (l = 8; l < 16; l++) - { - lo = l & 0xf; - if (diff <= gDeltaEncodingTable[l]) break; - } - } - else - { - for (l = 0; l < 8; l++) - { - lo = l & 0xf; - if (diff <= gDeltaEncodingTable[l]) break; - } - } - base += diff; - delta->data[j++] = (hi << 4) | lo; + base = pcm->data[i++]; + delta->data[j++] = base; + if (i >= pcm->length) { break; } + delta_index = get_delta_index(pcm->data[i++], base); + base += gDeltaEncodingTable[delta_index]; + delta->data[j++] = delta_index; + for (k = 0; k < 31; k++) { - diff = ((int8_t)pcm->data[i++]) - base; - if (diff > 49) diff = 49; - if (diff < -64) diff = -64; - if (diff < 0) - { - for (l = 8; l < 16; l++) - { - hi = l & 0xf; - if (diff <= gDeltaEncodingTable[l]) break; - } - } - else - { - for (l = 0; l < 8; l++) - { - hi = l & 0xf; - if (diff <= gDeltaEncodingTable[l]) break; - } - } - base += diff; - delta->data[j] = (hi << 4); if (i >= pcm->length) { break; } - diff = ((int8_t)pcm->data[i++]) - base; - if (diff > 49) diff = 49; - if (diff < -64) diff = -64; - if (diff < 0) - { - for (l = 8; l < 16; l++) - { - lo = l & 0xf; - if (diff <= gDeltaEncodingTable[l]) break; - } - } - else - { - for (l = 0; l < 8; l++) - { - lo = l & 0xf; - if (diff <= gDeltaEncodingTable[l]) break; - } - } - base += diff; - delta->data[j++] = (hi << 4) | lo; + delta_index = get_delta_index(pcm->data[i++], base); + base += gDeltaEncodingTable[delta_index]; + delta->data[j] = (delta_index << 4); + if (i >= pcm->length) { break; } - } - if (i >= pcm->length) - { - break; + delta_index = get_delta_index(pcm->data[i++], base); + base += gDeltaEncodingTable[delta_index]; + delta->data[j++] |= delta_index; } } |