diff options
Diffstat (limited to 'src/mixer.cpp')
| -rw-r--r-- | src/mixer.cpp | 23 |
1 files changed, 19 insertions, 4 deletions
diff --git a/src/mixer.cpp b/src/mixer.cpp index 5a8370df8..a2b296792 100644 --- a/src/mixer.cpp +++ b/src/mixer.cpp @@ -36,6 +36,19 @@ static uint32 _play_rate = 11025; */ static const int MAX_VOLUME = 128 * 128; +/** + * Perform the rate conversion between the input and output. + * @param b the buffer to read the data from + * @param frac_pos the position from the begin of the buffer till the next element + * @tparam T the size of the buffer (8 or 16 bits) + * @return the converted value. + */ +template <typename T> +static int RateConversion(T *b, int frac_pos) +{ + return ((b[0] * ((1 << 16) - frac_pos)) + (b[1] * frac_pos)) >> 16; +} + static void mix_int16(MixerChannel *sc, int16 *buffer, uint samples) { int16 *b; @@ -64,8 +77,9 @@ static void mix_int16(MixerChannel *sc, int16 *buffer, uint samples) } while (--samples > 0); } else { do { - buffer[0] = Clamp(buffer[0] + (*b * volume_left >> 16), -MAX_VOLUME, MAX_VOLUME); - buffer[1] = Clamp(buffer[1] + (*b * volume_right >> 16), -MAX_VOLUME, MAX_VOLUME); + int data = RateConversion(b, frac_pos); + buffer[0] = Clamp(buffer[0] + (data * volume_left >> 16), -MAX_VOLUME, MAX_VOLUME); + buffer[1] = Clamp(buffer[1] + (data * volume_right >> 16), -MAX_VOLUME, MAX_VOLUME); buffer += 2; frac_pos += frac_speed; b += frac_pos >> 16; @@ -105,8 +119,9 @@ static void mix_int8_to_int16(MixerChannel *sc, int16 *buffer, uint samples) } while (--samples > 0); } else { do { - buffer[0] = Clamp(buffer[0] + (*b * volume_left >> 8), -MAX_VOLUME, MAX_VOLUME); - buffer[1] = Clamp(buffer[1] + (*b * volume_right >> 8), -MAX_VOLUME, MAX_VOLUME); + int data = RateConversion(b, frac_pos); + buffer[0] = Clamp(buffer[0] + (data * volume_left >> 8), -MAX_VOLUME, MAX_VOLUME); + buffer[1] = Clamp(buffer[1] + (data * volume_right >> 8), -MAX_VOLUME, MAX_VOLUME); buffer += 2; frac_pos += frac_speed; b += frac_pos >> 16; |