V6 User Manual 1.00.book - Studio General

Optimizing PyramixUse TemplatesThe 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 creating your ownprojects and templates.Pyramix File Format .PMFWe 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 (theyuse 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 highersample 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 2to 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 youcan 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) recording on disk one sample ofchannel 1, then 1 sample of channel 2, and so on to 1 sample of channel n, .pmf was designed from day one tooptimize disk access by recording a quite large block of samples for each channel in a sequence. Typically 64 kB ofchannel 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 Sizesection of the Playback/Record page of All Settings > Settings > Application. However, the alternatives arereally only applicable to certain RAID and Network-Attached-Storage set-ups and, unless you have considerableknowledge and experience, the default setting should be used.One File Per Track optionFound in the All Settings > Settings > Project > Record page, The One file per track option should always bechosen (checked) whenever more than 2 tracks of recording are contemplated as there is a rather high potentialperformance 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 recording 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 allthe channels, even if only 1 or 2 tracks of that file are used at a given point in time.Reducing Unnecessary Disk AccessDSP optimizationTrack and Mixer MutingThere is a subtle difference between muting a Track Output (with the button in the Track Header) and mutingthe same signal in it’s associated mixer input strip. Muting a track stops disk access for the track (There is a delaybefore the sound stops while the replay buffer is emptied). Muting a mixer strip doesn't affect disk access but simplymutes the strip (Therefore muting is immediate). Muting track outputs enables multi-track recordings withmany tracks (E.g. 48 track music recordings) to be edited on hardware which cannot support this number of tracks.(E.g. a laptop) Providing the Clips are grouped across all tracks, then any editing changes made on the tracks usedfor the editing guide will also be reflected in the muted tracks. Track Grouping can be used to make operationsimpler and more convenient.At the core of the Mykerinos cards is a very powerful Trimedia VLIW (Very Long Instruction Word) processor. Thisfunctions as a kind of DSP chip and can do a lot of things including implement quite large real-time audio mixertopologies. However even this very powerful chip has its limits and while it is more than adequate in implementingsay a 48 input strips by 16 output bus configuration, it cannot be expected to implement a full "matrix mixer"Productivity : Optimizing Pyramix 25 - 437