diff options
| -rw-r--r-- | source/nds/entry.cpp | 22 |
1 files changed, 20 insertions, 2 deletions
diff --git a/source/nds/entry.cpp b/source/nds/entry.cpp index d82ed85..af832f9 100644 --- a/source/nds/entry.cpp +++ b/source/nds/entry.cpp @@ -981,8 +981,20 @@ void S9xGenerateSound () } } -#define SOUND_EMISSION_INTERVAL ((unsigned int) ((((unsigned long long) DS2_BUFFER_SIZE * 1000000) / SND_SAMPLE_RATE) * 3 / 128) - 1) /* -1 is for roundoff errors */ -unsigned int LastSoundEmissionTime = 0; +#define SOUND_EMISSION_INTERVAL ((unsigned int) ((((unsigned long long) DS2_BUFFER_SIZE * 1000000) / SND_SAMPLE_RATE) * 3 / 128)) +#define TRUE_SOUND_EMISSION_INTERVAL ((((double) DS2_BUFFER_SIZE * 1000000) / SND_SAMPLE_RATE) * 3 / 128) +#define SOUND_EMISSION_INTERVAL_ERROR ((int) ((TRUE_SOUND_EMISSION_INTERVAL - SOUND_EMISSION_INTERVAL) * FIXED_POINT)) +static unsigned int LastSoundEmissionTime = 0; + +/* + * Accumulated error in the sound emission time. The unit is as follows: + * FIXED_POINT = 42.667 microseconds. + * As the error goes past FIXED_POINT, the new target for sound emission + * becomes 42.667 microseconds LATER. This helps with sound buffer overruns, + * correctly dealing with the fact that 42.667 microseconds does not fit + * an integer number of times in 1/32000 second (or whatever sampling rate). + */ +static unsigned int SoundEmissionTimeError = 0; void S9xProcessSound (unsigned int) { @@ -1009,6 +1021,12 @@ void S9xProcessSound (unsigned int) else { LastSoundEmissionTime += SOUND_EMISSION_INTERVAL; + SoundEmissionTimeError += SOUND_EMISSION_INTERVAL_ERROR; + if (SoundEmissionTimeError > FIXED_POINT) + { + LastSoundEmissionTime += SoundEmissionTimeError >> FIXED_POINT_SHIFT; + SoundEmissionTimeError &= FIXED_POINT_REMAINDER; + } } /* Number of samples to generate now */ int sample_count = so.buffer_size; |