[Audacity-devel] latency in 1.3.7 and 1.3.6

[David B. <drb...@go...>]

Hi,

I measured the latency using the method mentioned on the list a while
back - generating a click track, and then putting a microphone next to
the speakers/headphones. I used a tempo of 1 per minute, and 1 beat to
the bar. Instead of recording just a single track, I repeated the
recording so the the project contained several tracks, and I could see
how much variation there was in the measurement.

This was done on Vista, with an on board radeon hd 3200 sound thing. I
checked with both an anologue mic, and logitech usb mic, and the
results are about the same. Latency correction was set to zero in
preferences.

On 1.3.6, the latency was about 60ms and varied over the repeated
recordings by about 10ms
On 1.3.7 using mme api, latency was about 170ms, again with about 10ms
variation.
0n 1.3.7 using directsound api, latency varied between about 170 and
220ms, and tended to be roughly 170ms or 220ms. Also, occasionally
some of the first beats were missing.

I thought that a magic number had been put in 1.3.7 to make the
default latency correction better? Any ideas about the large variation
for directsound? - is the driver not up to it?

David.