This driver is currently tested and verified to work on:
- Windows Vista x64 VM
- Windows 7 x64 VM
- Windows 10 1909 x64 (VM and Laptop)
- Windows 10 21296 x64 on a ThinkPad X1 Yoga 1st Gen with 3 different sound cards (Conexant CX20753/4, Scarlett Solo Gen 2, Aureon 7.1 USB)
This driver is capable of reaching very low latency in exclusive mode (~6ms on Scarlett Solo with 48kHz).
This PR addresses issue https://github.com/FluidSynth/fluidsynth/issues/758.
It ensures that the `internal buffer size` used by waveout device driver and the `extra buffers size` required by fluid_synth_process() are both coherent (i.e they should be of same size). To ensure this, both kind of buffers are now dependent of`audio.period` and `audio.period-size settings`.
Resets the default sample timer properly, allowing the internal
MIDI file player to restart its playlist on any other time but
the initial first.
Lets Qsynth play any MIDI files that are drag-n-dropped, anytime
after the first, following synth engine initialization.
In `fluid_rvoice_mixer.c`:`fluid_rvoice_mixer_process_fx()`:
If an audio processing callback is used, `mix_fx_to_out` would be `FALSE`. As a result, `in_ch` and `out_ch_l` points to the same buffer.
In `fluid_chorus.c`:`fluid_chorus_processreplace()`:
```C
/* process stereo unit */
/* store the chorus stereo unit d_out to left and right output */
left_out[sample_index] = d_out[0] * chorus->wet1 + d_out[1] * chorus->wet2;
right_out[sample_index] = d_out[1] * chorus->wet1 + d_out[0] * chorus->wet2;
/* Write the current input sample into the circular buffer */
push_in_delay_line(chorus, in[sample_index]);
```
Here the chorus processing code writes to the left output buffer (which will overwrite the input buffer in this case) before the sample from the input buffer is stored into the delay buffer, making the chorus output all zeros. If no audio processing callback is used, `mix_fx_to_out` would be `TRUE` and `in` and `left_out` will not point to the same buffer, therefore the order doesn't matter.
Simply swapping the two steps should be a sufficient fix. This patch also apply the same change to `fluid_chorus_processmix` only for the sake of consistency (since they are almost exact copies of each other).
Resolves#751.
