On Fri, Jun 03, 2011 at 02:10:37PM +0300, Alexey Suslikov wrote: > Hello tech@. > > aucat(1) manual says: > > Streams created with the -t option export the server clock using MTC, > allowing non-audio software or hardware to be synchronized to the audio > stream. The following sample rates (-r) and block sizes (-z) are > recommended for maximum accuracy: > > o 44100Hz, 441 frames > o 48000Hz, 400 frames > o 48000Hz, 480 frames > o 48000Hz, 500 frames > > For me, it was unclear why manual suggests different block sizes > for one frequency until I understood MTC resolution being 96, 100 > or 120 which is described much earlier in the manual. > > This is because I expected a bit self-explanatory text here so I can > think "aha, I saw these numbers earlier" or "ok, let's search why > these are 96, 100 and 120". Something like > > o 44100Hz, 441 frames (MTC resolution is 100) > o 48000Hz, 400 frames (MTC resolution is 120) > o 48000Hz, 480 frames (MTC resolution is 100) > o 48000Hz, 500 frames (MTC resolution is 96) >
ok, what about the diff below? > Moreover, above explanation of MTC and examples are somewhat > duplicate/overlap earlier -z description: > > -z nframes > The audio device block size in frames. This is the number of > frames between audio clock ticks, i.e. the clock resolution. If > a stream is created with the -t option, and MTC is used for > synchronization, the clock resolution must be 96, 100 or 120 > ticks per second for maximum accuracy. For instance, 120 ticks > per second at 48000Hz corresponds to a 400 frame block size. > > Is there any better way to explain this? With current text I forced to > jump up and down to understand what is what. I don't know, I take any ideas & diffs. Currently, we try to keep the DESCRIPTION section complete and self-consistent. Other sections are to give advices, and/or explain a little bit more how aucat works. If you don't use mtc (or you already know how mtc works), you don't need to read other sections and so no need to jump up and down. IMHO we need a section (or separate man page) about audio and midi concepts and about how aucat works. -- Alexandre Index: aucat.1 =================================================================== RCS file: /home/alex/sndio/cvs/sndio/aucat/aucat.1,v retrieving revision 1.16 diff -u -p -r1.16 aucat.1 --- aucat.1 3 Jun 2011 09:07:16 -0000 1.16 +++ aucat.1 3 Jun 2011 14:14:36 -0000 @@ -517,21 +517,23 @@ Streams created with the .Fl t option export the server clock using MTC, allowing non-audio software or hardware to be synchronized to the audio stream. +Maximum accuracy is achieved when the number of blocks per +second is equal to one of the standard MTC clock rates (96, 100 and 120Hz). The following sample rates .Pq Fl r and block sizes .Pq Fl z -are recommended for maximum accuracy: +are recommended: .Pp .Bl -bullet -offset indent -compact .It -44100Hz, 441 frames +44100Hz, 441 frames (MTC rate is 100Hz) .It -48000Hz, 400 frames +48000Hz, 400 frames (MTC rate is 120Hz) .It -48000Hz, 480 frames +48000Hz, 480 frames (MTC rate is 100Hz) .It -48000Hz, 500 frames +48000Hz, 500 frames (MTC rate is 96Hz) .El .Pp For instance, the following command will create two devices:
