You are strongly recommended to take a backup of your system before major installation and backups at
regular intervals.
6. Hardware Requirements & Performance Issues.
Digital Audio processing is a resource intensive task that relies heavily on the processing and I/O capabilities
of a system. I would strongly recommend a Pentium class machine as a minimum.
If you are going to be encoding from an analogue audio source via the line or microphone input, a PCI
soundcard will give the best results. The I/O performance difference between an ISA and PCI based card is
significant, over 132 MBytes/sec for PCI (quote taken from the PCI−HOWTO). Naturally, the better the
quality of the soundcard in terms of its signal−to−noise ratio, the better the encoded MP3. I've been using the
Soundblaster PCI128 and just switched over to a Soundblaster Live Value; both cards give good audio
performance, but the Live has significantly better S/N ratios, good enough for semi−pro audio work.
Remember the old data processing maxim:− garbage in − garbage out!
Creative have a Beta driver for the Soundblaster Live! which can be downloaded from:
http://developer.soundblaster.com/linux/
When recording analogue audio to a hard disk, more commonly referred to as direct to disk or d2d recording,
the performance of the disk, and its interface is critical. If you are using an IDE based based system, mode 4
or UDMA is preferable as the transfer rate is sufficiently high enough to provide reliable data transfer without
problems.
The ideal solution would be to use a SCSI based system as the drives and interface have far better throughput
capabilities, a sustained 5MB/sec for SCSI 1 through to 40−80MB/sec for ultra−ultra2/wide SCSI. IDE can
peak at anything from 8.3 MB/s to 66 MB/s for Ultra DMA mode 4 but these speeds are peak, average
transfer rates will be slower. If you can find, or afford, an AV SCSI drive, go for it. AV drives have had the
read/write head system optimised for continuous data transference; other SCSI and IDE drives normally
cannot sustain continuous data transfer as the write head heats up!
Naturally a drive that has cache will give more consistent results than one that doesn't, as the cache will act as
a buffer if the heads do lift or it cannot handle the throughput.
If your drive isn't up to spec, your recording will suffer from dropouts and glitches, where the drive failed to
record the signal. If you are recording one−off events, such as live performances invest in a good SCSI based
disk system.
Another cause of d2d dropouts is a heavily loaded system. Background tasks can cause the system to
momentarily glitch. Its recommended to run as few background services as you can, especially networked
based services. For more information about setting network services, and startup scripts please refer to the
SAG and NAG guides.
Virtual memory paging will also cause glitches, so run with as much physical RAM as you can, I'd
recommend at least 32 Mb, but you may well need more.
For those wanting to extract the most out of their system, optimising the kernel probably wouldn't do any
harm either.
The Linux MP3−HOWTO
6. Hardware Requirements & Performance Issues. 5
