Help! Problème de surchage du cache disque

Citation : The Problem: "My Cubase SX audio glitches when it's playing back just one audio track, when there are another 52 muted. I'm using my Audiophile 2496 ASIO driver and have a 3.2GHz Pentium 4 PC with 1.5GB RAM."

The Diagnosis: Here's an intriguing one. You wouldn't expect any PC to have problems replaying a single audio track. The twist in this tale is that while the muted audio tracks aren't contributing to the mix, they are still being streamed by Cubase, just in case you hit those mute buttons and want the tracks instantly added to your mix. Whichever sequencer you use, you can confirm such behaviour either by watching its Disk Meter load, or by saving your song, deleting all but the one track and trying again. Your hard drive should now show minimal loading. Even the CPU overheads of plug-ins used by muted tracks are still weighing down your song, whether you hear them or not, although in this case you can temporarily disable them via their on/off switches.

So in reality this person is running 53 audio tracks and, assuming that these are 24-bit/96kHz, is beginning to aproach the limits of most single 7200pm hard drives. I've personally managed to run 76 mono 24-bit/96kHz tracks on my Seagate Barracuda SATA 80Gb ST380013AS audio drive before it ran out of steam, but this was with long tracks, each lasting the whole duration of a song. With shorter parts being dropped in and out, some audio editing and some inevitable file fragmentation, this figure will certainly drop.
pcMusician0706 3
In this Cubase SX Project, you can see that the Disk Meter (lower left) is displaying an overload, even though only a single audio track is actually playing. Muting the other 50 or so tracks makes no difference, because they are still being streamed in anticipation of you un-muting them and wanting to hear them immediately.

If you're also running a soft sampler such as HALion or Kontakt inside your sequencer, this can greatly increase the load on your hard drive. You need to be especially careful if you're running a separate soft sampler such as Gigastudio, since its additional load (both CPU and Disk) may not show up on your sequencer's performance meters.

There's another fairly common reason for a hard drive to conk out when it's only playing back a couple of dozen audio tracks. This problem is often exhibited as intermittent glitches (even though the sequencer's CPU meter displays a low overhead reading), and it's due to an unsuitable Buss Master DMA mode. You can check this inside Device Manager:

Select 'View Devices By Connection'.

Locate the Storage Controllers on the list, expand their entries, and you'll find your hard drives and optical drives attached to either Primary or Secondary Channels.

Right-click on the Channel connected to each drive and select 'Properties'.

Click on the Advanced Settings tab. For each of the two devices that can be connected to each channel you'll find a Device Type (normally set to 'Auto Detection'), and a Transfer Mode, which should read 'DMA if available'.

If it reads 'PIO Only', your hard drive will be running well below par, so change it to the other setting, click on the OK button and then reboot your PC. (When this Transfer Mode does read 'DMA if available', the 'Current Transfer Mode' box beneath it should typically display 'Ultra DMA Mode 5'.)

A quick way to check the performance of your hard drive is with a utility such as Dskbench (www.sesa.es/us/dl/dskbench.zip) or HDTach (www.simplisoftware.com/Public/index.php?request=HdTach). These will show up whether or not your hard drive is using the most suitable DMA mode. You should achieve an average or sustained read speed of at least 40MB/second with most modern hard drives, with a CPU utilisation of two percent or less.

The Workarounds: If your hard drive is operating in the correct mode but you still regularly find it beginning to struggle, there are several ways forward. For a start, defragmenting your audio drive may improve matters (although occasionally this may make things worse — see PC Musician June 2005 for more details).

If you're running a VST soft sampler and have plenty of spare system RAM, you may be able to offset some drive load into this, courtesy of its disk-streaming parameters. Alternatively, it may be time to investigate the partitioning options I discussed in the 'Partition Decisions' feature in SOS May 2005. Creating a separate partition just large enough for the current project, on the fastest 'outside' portion of your drive, may let you run more audio tracks without spending any more money at all, assuming that you've already got a suitable partition utility, such as Symantec's Partition Magic, Paragon Software's Partition Manager, or Acronis' Disk Director Suite.

In the long term, you should also ask yourself whether you can actually hear the improvements offered by higher sampling rates such as 96kHz on your system. Remember that not only will these more than double the hard-disk load over using a 44.1kHz sample rate, but also that any plug-ins and soft synths you use will consume more than twice as much CPU overhead, as proportionally more calculations are needed per second. At the very least, anyone whose final format is to be Red Book Audio CD should consider moving from 96kHz to 88.2kHz on future projects, if their audio interface offers that sample rate. This will reduce drive loading by over eight percent.

If you're running absolutely loads of audio tracks (one SOS Forum poster admitted to a song containing 330, but with only 50 to 75 at any one time!) you should perhaps take a closer look at your working methods, unless you're mocking up an orchestral score and layering multiple instruments for each part. If this isn't the case, perhaps rethinking your working methods will result in significantly less hard drive torture.

However, ultimately it may be time to invest in faster hard drives: a 10,000rpm model should boost your audio track count significantly, or you could investigate RAID (Redundant Array of Independent Disks) by installing two identical drives configured as RAID 0, to potentially double the overall transfer rate. Just remember that your data is more precarious on such a system, because it's spread across multiple drives. Also bear in mind that both 10,000rpm and multiple drives are likely to increase the overall acoustic noise level of your PC.

Citation : as-tu plusieurs versions de sauvegardes de ton projet (ça vaudrait le coup de charger une ancienne, pour voir) ?

lance carrément un autre projet et voit si ça le fait toujours

Hors sujet : t'as réussi à caler la voix?