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Setting up the latency
In digital systems the processing of audio data always comes along with a
certain delay time. Here is where you get to know, how to set up and
optimize this delay time (latency) for the TRACE PRO AE.
Background
Within a computer, digital audio data is transported in small packages, the
so called buffers. Thus, an audio signal is split up in little portions (data
packages) and is send away piece by piece. Looking at the TRACE PRO
AE, these buffers have to be send from audio application to the driver of
the TRACE PRO AE. This one takes care, that the buffers find their way
via the PCI socket (PCI Controller) to the TRACE PRO AE. If a recording
is to be managed with the TRACE PRO AE, all of the mentioned happens
in reverse.
Let’s make this a little clearer with an example: A composer wants to write
a little piece for a piano player. So in just five minutes he fills the first piece
of paper with lots of notes. He then hands the paper to the musician who
instantly starts to transform these notes into beautiful melodies. He, too, is
now busy for five minutes. The composer could have written two pieces of
paper in ten minutes, just as well, while the musician continues to play one
piece of paper in five minutes. In order for the musician to continuously
play, so the music won’t stop, the composer must not write less then one
score in five minutes.
In this example, the piece of paper is the audio buffer. Just like it contains
notes, the buffer contains audio data. The composer is the audio application
sending buffers via the audio driver. The musician is the TRACE PRO AE,
which receives these buffers via the PCI Controller. The PCI Controller
operates with the DMA latency defined by the DMA buffer. In order for the
continuous data stream to not break up, the buffers of the audio application
must not be smaller than the DMA latency (DMA buffer size)
