Optimizing Pyramix; Use Templates; Pyramix File Format .Pmf; One File Per Track Option - Merging Pyramix 4.3 User Manual

Optimizing Pyramix

Use Templates

The supplied Templates have settings appropriate to their purpose and are the fastest way of optimizing
Pyramix. However, the following information should help when deciding what settings to use when cre-
ating your own projects and templates.

Pyramix File Format .PMF

We strongly recommend the use of the native .PMF format for a number of reasons.
The first issue is the size limitation of the WAV and BWF formats. These are LIMITED TO 2 GB in size
by design (they use 32 bit signed, which gives a total of 2 to the power of 31 Bytes addressable =
2'147'483'648 Bytes precisely).
2GB may sound a lot but a little elementary arithmetic will show it is easy to exceed this limit when using
higher sample rates and bit depths for multi-track recordings of real-world durations.
AIFF is slightly better in the sense that it is "only" LIMITED TO 4 GB (it uses 32 bit unsigned, which
gives a total of 2 to the power of 32 Bytes addressable = 4'294'967'296 Bytes precisely.
PMF uses 64 bit addressing which would probably allow 128 tracks to be recorded for about 10,000
years (If you can afford the disks!), which should be more than enough for any practical applications.
The second advantage of the Pyramix File Format for large multitrack projects is that it is not "sample-
interleaved" but "block-interleaved". Which means that instead of (as with WAV, BWF and AIFF) record-
ing on disk one sample of channel 1, then 1 sample of channel 2, and so on to 1 sample of channel n,
.pmf was designed from day one to optimize disk access by recording a quite large block of samples for
each channel in a sequence. Typically 64 kB of channel 1, then 64 kB of channel 2, etc, finally 64 kB of
channel n.
This setting (default 64 kB) can be changed by the user to one of four alternative values in the Record
Block Size section of the General Settings dialog box under the Playback Tab. However, the alterna-
tives are really only applicable to certain RAID and Network-Attached-Storage set-ups and, unless you
have considerable knowledge and experience, the default setting should be used.

One File Per Track option

Found in the Settings > Project Information and Settings dialog box on the Record page, The "one
file per track" option should always be chosen (checked) whenever more than 2 tracks of recording are
contemplated as there is a rather high potential performance penalty that can occur with all the sample-
interleaved file formats (E.g.WAV and AIFF) on playback, when not all tracks of a multi-channel record-
ing are used or played in their original sync relationship on the Timeline. This is because with other,
interleaved, formats the hard disk head will still have to go through all the bits of all the channels, even if
only 1 or 2 tracks of that file are used at a given point in time.

DSP optimization

At the core of the Mykerinos cards is a very powerful Trimedia VLIW (Very Long Instruction Word) pro-
cessor. This functions as a kind of DSP chip and can do a lot of things including implement quite large
real-time audio mixer topologies. However even this very powerful chip has its
limits and while it is more than adequate in implementing say a 48 input strips by 16 output bus configu-
ration, it cannot be expected to implement a full "matrix mixer" of say 64 inputs by 64 outputs with a full
independent multiply/add + individual delay on each matrix node on what would be a 64 x 64 = 4096
nodes, while also taking care of all the other housekeeping tasks such as locking with ultra low jitter to
User Manual : Optimizing Pyramix
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