Export to MP3 is slow


First of all: a Happy New Year to everybody (for over a few day).
Second: Audacity is a great product
Third: My question:

I’m using Audacity every weekend. I need to Bass Boost an 8 hour mp3 file.
Loading the file in Audacity takes about < 3 mins. Adding the Bass about < 2 mins.
Those are great times but when exporting to file to a .mp3 it takes about 20 mins. Way too long.

I have a Core i7 3610QM at 2.3Ghz (3.3Ghz Turboboost) and while exporting, my CPU is only loaded 12% by Audacity.
I also have an SSD (Samsung 830) in my system, so my writing speeds are good.

Isn’t it possbile that Audacity may use about 80-90% from my CPU to export the file to an .mp3. I know it’s possible to get the job done quicker.

btw: Sorry for my English :wink:

Probably not because Audacity does not support multiple CPU cores.

What MP3 settings are you using? VBR settings are likely to be a bit quicker than CBR.

The job is not to edit an MP3 file. Audacity is not an MP3 or WAV editor.

Audacity works internally at uncompressed 44100 (or whatever your settings are) and 32-bit floating. When you do a special effect, Audacity has to make an UNDO file the same size as the show. So the overall job is three times the size of an uncompressed file at 8 hours. Multiple gigs. How much room do you have left on your SSD? How much memory do you have? I bet Audacity is memory choking – running out of hardware memory and having to push compression tasks off to the “hard drive,” never a fast process, particularly if it starts running out of SSD cache, too.


Isn’t it possible to code that Audacity uses multiple CPU cores? Most CPU’s these days are multicore.

The recorded file to edit is an 128kbps .mp3. About 440 MB. Encoded with lame_enc. No VBR.

I have 82.5 GB left on my SSD (Samsung 830 128 GB SSD). Enough I think :wink:.

Probably, but there’s about 160,000 code lines in Audacity - it’s not a small job.

According to the test results here: http://www.hydrogenaudio.org/forums/index.php?showtopic=87095&st=0&p=746331&#entry746331
128 kbps CBR is the slowest MP3 encoding for LAME.

Something for 2013 :wink:

Okay thanks. I saw something about fpMP3Enc in this thread (page 2).
How can I use that encoder to export my file? I can chose export to .mp3 and I need to select lame_enc.dll. It’s easy. But I don’t know how to use that fpMP3Enc.

Audacity may be able to use fpMP3Enc as an external encoder. See: http://manual.audacityteam.org/o/man/exporting_to_an_external_program.html
(I’ve not tried it myself).
More information about fpMP3Enc: http://www.hydrogenaudio.org/forums/index.php?showtopic=73790&st=0

Thank you!