[espeak-ng:master] reported: sluggish speech interruption #github
firstname.lastname@example.org Integration <espeak-ng@...>
[espeak-ng:master] New Comment on Issue #172 sluggish speech interruption
I still got reports from user finding sluggish interruption. I tried various audio setups, and one which indeed brings me sluggish interruption seems to be when pcaudiolib is using alsa with mmap output. In that case, espeak-ng gets stuck inside the snd_pcm_writei call, apparently because there is not much room left in some kernel buffer, or some such. The recent patches thus do not improve things, since we're stuck having to wait for the 200ms of output being emitted.
I could reduce the issue strongly by reducing the buffer size of espeak-ng, in espeak_ng_InitializeOutput, e.g. to 50ms. Actually I'm surprised that the value is hardcoded such a high value as 200ms, while there are various studies which have shown that humans feel bad interactivity when latency is over 100ms. I'd argue to reduce the default buffer size to 50ms, which should only cost 4x more audio roundtrips, while improving latency considerably in cases where audio gets stuck