Personal tools

Jack frame, period, buffer info

From Rivendell Wiki

Jump to: navigation, search

Date: Wed, 15 Aug 2007 19:33:02 +0200
Subject: Re: [Jackit-devel] Meant of periods and frames

On Wednesday 15 August 2007, zappa wrote:
> Hi people,
> i'm a new user of jack at all, i'm italian => i don't speak english...
> the question:
> I don't understand what is the FRAMES/PERIOD and the PERIODS/BUFFER,
> the definition in the man page of jackd is confused for me.
> If possible i would want a theorist definition of it.
> Example:
> the sample rate is the frequency of sampling, the amount of samples take
> >from the input;
> frames/period and periods/buffer what is practically?
> Sorry for my english...I hope is understood my problem
> ciao

A frame of audio means 1 sample per channel.. E.g. if you have a 6-channel
signal and you process one frame of it you have processed one sample per
channel, 6 samples in total..

frames/period means frames per processing cycle (e.g. if you have 64
frames/period, then the buffersize per channel is 64 samples)

periods/buffer means how many periods are there [on windows a period is more
often called a "buffer"]. But in a typical double buffer scheme you have e.g.
two buffers combined into a single chunk of memory.. And in alsa speak, this
combined buffer is the "buffer" and the individual chunks in the buffers are
called periods [kinda, the terminology is a little squishy] So one period is
the first half of the buffer and the other period is the second half of the