diff options
Diffstat (limited to 'source')
| -rw-r--r-- | source/soundux.cpp | 88 |
1 files changed, 71 insertions, 17 deletions
diff --git a/source/soundux.cpp b/source/soundux.cpp index d8ce223..b8df25a 100644 --- a/source/soundux.cpp +++ b/source/soundux.cpp @@ -840,6 +840,9 @@ void DecodeBlock (Channel *ch) filter = *compressed; if ((ch->last_block = filter & 1)) ch->loop = (filter & 2) != 0; + + int16 interim[16]; + uint8 interim_byte; compressed++; signed short *raw = ch->block = ch->decoded; @@ -899,29 +902,80 @@ void DecodeBlock (Channel *ch) int16 result = (signed short)(out<<1); if (abs(result) > amplitude) amplitude = abs(result); + interim[interim_byte++] = out; prev1=(signed short)prev0; prev0=(signed short)(out<<1); } } ch->previous [0] = prev0; ch->previous [1] = prev1; - // Make it a square wave with an amplitude equivalent to that - // of the highest amplitude sample of the block. - /* for (i = 0; i < 8; i++) - ch->decoded[i] = amplitude; - for (i = 8; i < 16; i++) - ch->decoded[i] = -amplitude; */ - // Make it a triangle wave with an amplitude equivalent to that - // of the highest amplitude sample of the block. - ch->decoded[0] = ch->decoded[8] = 0; - ch->decoded[1] = ch->decoded[7] = amplitude / 4; - ch->decoded[2] = ch->decoded[6] = amplitude / 2; - ch->decoded[3] = ch->decoded[5] = amplitude * 3 / 4; - ch->decoded[4] = amplitude; - ch->decoded[9] = ch->decoded[15] = -(amplitude / 4); - ch->decoded[10] = ch->decoded[14] = -(amplitude / 2); - ch->decoded[11] = ch->decoded[13] = -(amplitude * 3 / 4); - ch->decoded[12] = -amplitude; + + int32 total_deviation_from_previous = 0; + for (i = 1; i < 16; i++) + total_deviation_from_previous += abs(interim[i] - interim[i - 1]); + if (total_deviation_from_previous >= (int32) amplitude * 4) + { + /* Looks like noise. Generate noise. */ + for (i = 0; i < 16; i++) + { + int feedback = (noise_gen << 13) ^ (noise_gen << 14); + noise_gen = (feedback & 0x4000) ^ (noise_gen >> 1); + ch->decoded[i] = (noise_gen << 17) >> 17; + } + } + else if (interim[0] < interim[1] && interim[1] < interim[2] + && interim[2] < interim[3] + && interim[4] > interim[5] && interim[5] > interim[6] + && interim[6] > interim[7] && interim[7] > interim[8] + && interim[8] > interim[9] && interim[9] > interim[10] + && interim[10] > interim[11] + && interim[12] < interim[13] && interim[13] < interim[14] + && interim[14] < interim[15]) + { + /* Looks like a sine or triangle wave. Make it a + * triangle wave with an amplitude equivalent to that + * of the highest amplitude sample of the block. */ + ch->decoded[0] = ch->decoded[8] = 0; + ch->decoded[1] = ch->decoded[7] = amplitude / 4; + ch->decoded[2] = ch->decoded[6] = amplitude / 2; + ch->decoded[3] = ch->decoded[5] = amplitude * 3 / 4; + ch->decoded[4] = amplitude; + ch->decoded[9] = ch->decoded[15] = -(amplitude / 4); + ch->decoded[10] = ch->decoded[14] = -(amplitude / 2); + ch->decoded[11] = ch->decoded[13] = -(amplitude * 3 / 4); + ch->decoded[12] = -amplitude; + } + else if (interim[0] > interim[1] && interim[1] > interim[2] + && interim[2] > interim[3] + && interim[4] < interim[5] && interim[5] < interim[6] + && interim[6] < interim[7] && interim[7] < interim[8] + && interim[8] < interim[9] && interim[9] < interim[10] + && interim[10] < interim[11] + && interim[12] > interim[13] && interim[13] > interim[14] + && interim[14] > interim[15]) + { + /* Inverted triangle wave. */ + ch->decoded[0] = ch->decoded[8] = 0; + ch->decoded[1] = ch->decoded[7] = -(amplitude / 4); + ch->decoded[2] = ch->decoded[6] = -(amplitude / 2); + ch->decoded[3] = ch->decoded[5] = -(amplitude * 3 / 4); + ch->decoded[4] = -amplitude; + ch->decoded[9] = ch->decoded[15] = amplitude / 4; + ch->decoded[10] = ch->decoded[14] = amplitude / 2; + ch->decoded[11] = ch->decoded[13] = amplitude * 3 / 4; + ch->decoded[12] = amplitude; + } + else + { + // Make it a square wave with an amplitude equivalent to that + // of the highest amplitude sample of the block. + // But actually put half of the amplitude, because + // square waves are just loud. + for (i = 0; i < 8; i++) + ch->decoded[i] = amplitude / 2; + for (i = 8; i < 16; i++) + ch->decoded[i] = -amplitude / 2; + } } else { |