In the Record Window are features such as “Auto Start On Sound Detection” and “Auto Stop after Duration”. I like these wonderful WL features and have come to use them more and more. However, I have always noticed that the resulting file’s duration seldom matches the intended times I had programmed. In the past I just shrugged this off. But I find more and more that computer savvy clients (and internet train spotters) get shaken when exact timings are not seen. I ran some tests this morning to provided factual data:
TEST 1: Auto Stop after Duration = 0:00:20
Pass1 = 0:00:20.225
Pass2 = 0:00:20.317
Pass3 = 0:00:20.201
TEST 2: As above plus Auto Start on Sound Detection = -71dB/200ms (-40dBFS trigger signal)
Pass1 = 0:00:20.540 (measured preroll = 183ms)
Pass2 = 0:00:20.563 (measured preroll = 181ms)
Pass3 = 0:00:20.517 (measured preroll = 198ms)
As you can see, each pass is a different duration from each other and NONE of them match the intended, programmed duration of 0:00:20.000. Very strange! Especially in Test 1, where there is no tolerance involved with signal detection. Exact and repeatable results should occur. It does seem the trigger for Auto Start is reasonably reliable.
So what’s the deal?