Song tempo automation in Ableton Live is not continuous

I just figured something out that would have saved me a lot of trouble if it had been mentioned in the Live manual: Live's song tempo automation is not continuous (in version 7 and below). Although you can draw a ramp in the song tempo automation lane, Live will only sample its value, and adjust the song tempo accordingly, at the beginning of each 16th grid line.

In the following diagram we can see that the tempo automation changes at A and B have no effect on the song tempo (we can tell because the waveform display of the repeating audio clip stays the same). The only tempo change that is picked up is C, because Live is only sampling the automation value at the beginning of every 16th.



This is pretty disappointing, and has consequences for anyone wanting to implement the 'fake groove quantize' approach that I talked about in a previous post.