Audacity Forum

Dear Audacity community,

I am having difficulty using Audacity 1.3.4 running on Ubuntu 8.04 (Kernel 2.6.24-23-generic) on a Sempron 2400+ with 947 MB of RAM. Namely, when I import a .wav file of any significant length (~ 9 min.) Audacity becomes unusably slow. The system monitor shows the CPU usage pegging high whenever I try to select part of the file, switch to/from another app, etc. I have verified that the degree of slowdown is proportional to the size of the audio file. I have no such difficulties running 1.2.6 on XP. I saw a post on this forum about slow performance and did an hdparm.



hdparm -I gave the following:

/dev/sdb1:

ATA device, with non-removable media
Model Number: WDC WD1200JD-22HBC0
Serial Number: WD-WCAL96550035
Firmware Revision: 08.02D08
Standards:
Supported: 6 5 4
Likely used: 8
Configuration:
Logical max current
cylinders 16383 16383
heads 16 16
sectors/track 63 63
--
CHS current addressable sectors: 16514064
LBA user addressable sectors: 234441648
LBA48 user addressable sectors: 234441648
device size with M = 1024*1024: 114473 MBytes
device size with M = 1000*1000: 120034 MBytes (120 GB)
Capabilities:
LBA, IORDY(can be disabled)
Standby timer values: spec'd by Standard, with device specific minimum
R/W multiple sector transfer: Max = 16 Current = 16
Recommended acoustic management value: 128, current value: 254
DMA: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 udma5 *udma6
Cycle time: min=120ns recommended=120ns
PIO: pio0 pio1 pio2 pio3 pio4
Cycle time: no flow control=120ns IORDY flow control=120ns
Commands/features:
Enabled Supported:
* SMART feature set
Security Mode feature set
* Power Management feature set
* Write cache
* Look-ahead
* Host Protected Area feature set
* WRITE_BUFFER command
* READ_BUFFER command
* DOWNLOAD_MICROCODE
Power-Up In Standby feature set
* SET_FEATURES required to spinup after power up
SET_MAX security extension
Automatic Acoustic Management feature set
* 48-bit Address feature set
* Device Configuration Overlay feature set
* Mandatory FLUSH_CACHE
* FLUSH_CACHE_EXT
* SMART error logging
* SMART self-test
* SATA-I signaling speed (1.5Gb/s)
* Host-initiated interface power management
* SMART Command Transport (SCT) feature set
* SCT Long Sector Access (AC1)
* SCT LBA Segment Access (AC2)
* SCT Error Recovery Control (AC3)
* SCT Features Control (AC4)
* SCT Data Tables (AC5)
Security:
Master password revision code = 65534
supported
not enabled
not locked
not frozen
not expired: security count
not supported: enhanced erase
Checksum: correct

I would hate to have to boot over to XP whenever I want to use Audacity. Can anyone help out a Linux/Audacity newb? Any advice would be greatly appreciated.

buelligan

The thing that makes the biggest difference (by a very long way) on my computer (Pentium III 500MHz / Ubuntu 8.10) is the device settings.
You should definitely use ALSA rather than OSS (JACK is best if you can get it to work).
Assuming that you are using ALSA, if your sound card does not have hardware mixing capability, try using "ALSA: dmix" for playback.

When possible, the project rate and the sample rate of the tracks should match so as to avoid overheads with sample rate conversion. If this is not possible, make sure that the Real-Time conversion settings are set to "Fast" and "Dither = none" (see Edit menu > Preferences > Quality tab).