PaStreamParameters suggestedLatency < 0.0 behavior is not specified and not handled correctly

[RossBencina]

The documentation for PaStreamParameters suggestedLatency does not mention negative latencies.

I have not reviewed all host APIs but at least pa_win_wmme.c and pa_win_ds.c assume that suggestedLatency is non-negative, and directly assign to an unsigned long (BAD!!), for example in pa_win_ds.c:

unsigned long suggestedInputLatencyFrames, suggestedOutputLatencyFrames;
...
suggestedInputLatencyFrames = (unsigned long)(inputParameters->suggestedLatency * sampleRate);
...
suggestedOutputLatencyFrames = (unsigned long)(outputParameters->suggestedLatency * sampleRate);

There is equivalent code in pa_win_wmme.c.

The fix should be to clamp to 0, e.g.

if (inputParameters->suggestedLatency >= 0.0)
   suggestedInputLatencyFrames = (unsigned long)(inputParameters->suggestedLatency * sampleRate);
else
   suggestedInputLatencyFrames = 0;

TODO:

• Add documentation, something like "If suggestedLatency is less than zero, it is treated as if it is zero."
• Fix code in pa_win_wmme.c (clamp to 0)
• Fix code in pa_win_ds.c (clamp to 0)
• Review other host APIs (first list them here)
• Add test for negative suggested latency #855

There is already a PR which will fix this for PA/PulseAudio #849

[RossBencina]

Related #99