latency issues about python-soundfile HOT 4 CLOSED

This is a very common issue with laptop sound cards, particularly on OS X. Apparently, OS X shuts down the sound hardware completely if no sound is playing. In this case, it can take some time for the sound card to wake up until it is responsive.

You can actually see this in OS X itself, too. If you haven't played a sound in a while and start playing one from the Finder, the first time will start with a short delay. After that, it will play sounds without delay. Thus, it is probably an issue with OS X or CoreAudio, and out of reach for portaudio or pysoundcard.

I don't know whether similar behavior exists on other OSes or hardware, but I certainly have never seen it anywhere else yet.

from python-soundfile.

Interesting, good to know! That's my situation exactly.

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I can confirm that playing a very short, effectively silent sound once every 20 seconds in a loop within a separate python process completely fixes this, while being undetectable by ear.

from python-soundfile.

That's good to know!

Doesn't it work with an actually silent sound (all zeros) instead of an effectively silent one?

Anyway, If you really care about exact timing, you should use a stream which is always running and find out in the callback function if something has to be played back or not.
To achieve a constant latency (with little jitter), you can use the method Stream.time() to get the time when your actual event occurs and use this time value in the callback to determine the correct time for starting the playback (relative to the current block beginning).
Alternatively, you can also always play immediately at the block beginnings, which reduces latency but increases jitter. If the rhythmic succession of events doesn't matter, the latter should suffice.

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