Re: [LAU] Estimating JACK latency

On Mon, Apr 16, 2012 at 04:54:45PM -0400, Paul Davis wrote: Hi, I could use some help with a real example. Example 1. system to ecasound Say I ask Ecasound to route one channel of audio from the sound card input to the null device. ecasound -f:,1 -i:jack,system -o:null How much is the signal delayed on the way from the soundcard into Ecasound's signal-processing engine, as reported by jack_port_get_latency_range() ? The connection (reported by jack_lsp -c) is system:capture_1 to ecasound:in_1 Here is the relevant output of jack_lsp -l: system:capture_1 port latency = 1024 frames port playback latency = [ 0 0 ] frames port capture latency = [ 1024 1024 ] frames ecasound:in_1 port latency = 0 frames port playback latency = [ 0 0 ] frames port capture latency = [ 1024 1024 ] frames Without looking at the source, I can hazard a guess that the "port latency" line may be the output of a deprecated function, perhaps jack_port_get_latency(). So let's remove that for clarity: system:capture_1 port playback latency = [ 0 0 ] frames port capture latency = [ 1024 1024 ] frames ecasound:in_1 port playback latency = [ 0 0 ] frames port capture latency = [ 1024 1024 ] frames Now which of these four ranges contributes to the latency? Reading the docs, my naive guess is that only two ranges play a part, probably the capture latency of the first and the playback latency of the second, for the total of 1024 frames. I'm curious if the other two ranges have any meaning at all, given that ports appear to have only one direction. Well that's the extent of my questions for tonight. TIA, Joel -- Joel Roth