Quad cores benchmarks and LAME 
Tuesday, November 7, 2006, 12:39 PM - LAME
Some samples of Intel "quad cores" processors are now available. As with the introduction of dual cores, we'll see a lot of hardware websites doing some benchmarks. Several of them will also use LAME encoding as one of the tests.

In the current version (3.97) LAME is not multithreaded at all, so for a single encoding it's obvious that adding cores will not change anything, no need to run a benchmark to know it, and no need to display bar graphs of encoding speed results (as they are quite pointless).

Message to benchmarkers:

If you want to use mp3 encoding for a multicores/multiprocessors benchmarks, then you have the following choices:

*use a natively multithreaded encoder (example: iTunes)

*use a multithreaded frontend and encode several files. As an example, EAC allows you to choose the number of threads. If you use more than 1, of course you will benefit from the added cores.
  |  0 trackbacks   |  permalink   |  related link

LAME encoding speed evolution 
Saturday, October 28, 2006, 01:27 PM - LAME
For the sake of curiosity, I tested the evolution of encoding speed of Lame using different versions. To simplify things, encoding is done at default settings (128kbps/cbr). Computer features MMX/3dnow/SSE/SSE2, audio file is about 1 minute long.

Here are the results:

3.20: 3.51s
3.50: 6.49s
3.70: 3.78s
3.80: 3.70s
3.90: 3.74s
3.93.1: 4.58s
3.96.1: 5.53s
3.97: 5.31s

By looking at this, it's clear that overall Lame has became slower over time. We tryed to keep speed reasonable, but as we increased quality our speed optimisations were not enough to compensate for the extra computations.

We had a notable speed decrease when releasing 3.94. In 3.94, we switched our default psychoacoustic model from GPsycho to NSPsytune. NSPsytune was already used (starting with 3.90) when using the preset/alt-preset settings. To have a comparison value, here is the "preset cbr 128" speed of versions prior to 3.94:

3.90 --alt-preset cbr 128: 9.62s
3.93.1 --preset cbr 128: 6.55s

So between 3.90 and 3.97, NSPsytune's encoding time decreased from 9.62s to 5.31s. Not bad at all, but still quite slower than early Lame releases.
  |  0 trackbacks   |  permalink   |  related link