Thanks, Builds and runs fine on Debian Wheezy AMD64. What latency would be considered average? What numbers should one expect? Cheers, S.M. On Mon, Apr 18, 2011 at 08:21:26PM +0000, Fons Adriaensen wrote: > Hello all, > > A new release of jack_delay is available at > <http://kokkinizita.linuxaudio.org/linuxaudio/downloads> > > > From the README: > > jack_delay 0.4.0 - 18/04/2011 > ------------------------------- > > Jack_delay can be used to measure the round-trip latency of a soundcard. > To do this, start the program and connect like this: > > jack_delay -> playback_port -> cable from soundcard output to input -> capture port -> jack_delay > > Jack_delay generates a signal consisting of 13 sine waves, measures the > phase difference between the input and output for each of these, and > computes the delay from those phase differences. The algorithm used is > one developed originally for satellite ranging - that is measuring the > distance between a satellite and a ground station. > > With a good sound card jack_delay will measure the round-trip latency > with an accuracy of around 1/1000 of a sample. The assumption is that > the delay is more or less independent of frequency. The actual value > displayed is the one for a frequency of 1/16 of the sample rate. The > phase measurement for this frequency of course only provides a result > in the range of 0..16 samples. The other frequencies are used to extend > this interval to 4096 * 16 samples, more than a second at 48 kHz. > This release should be much less sensitive to frequency-dependent delay > than the previous ones. > > The following options are avaiable (use jack_delay -h to see them): > > -O playback port connect output to named port. > -I capture port connect input to named port. > -E show excess latency instead of full latency. > > Using -E requires -O and -I, as the the computation depends on > the latency values reported by jack for the ports used. > The excess latency is the measured value minus the expected one, > taking into account any corrections set by jack's -I and -O options. > That is, if you have the right values for these options, then the > value displayed with -E will be at most +/- half a sample. > > To determine the correct values for jack's -I and -O, set both > of them to zero ('default' in qjackctl) and measure the latency > using the -E option. Then set each of the -I and -O options to > half the value displayed. > > > Ciao, > > -- > FA > > > _______________________________________________ > Linux-audio-user mailing list > Linux-audio-user@xxxxxxxxxxxxxxxxxxxx > http://lists.linuxaudio.org/listinfo/linux-audio-user -- _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/listinfo/linux-audio-user
