iTunes MP3 CODEC: Strange Setting? It use LAME or other?, Smart Encoding and 10 Hz Filter???? Options

[Antigen]

Hi to all,

I hope that some one have experience with the iTunes MP3 ENCODER.

I don't know if iTunes use LAME or other encoder for MP3 but I have see strange setting in the setup page-

My setting are:

- STEREO BIT RATE 320 KBPS
- SAMPLE RATE: AUTO
- CHANNELS: AUTO
- STEREO MODE: JOINT STEREO

- SMART ENCODING ADJUSTMENTS ON
- FILTER FREQUENCIES BELOW 10 Hz

But what is the SMART ENCODING ADJUSTMENT?

And is not a bad idea filter the frequencies below 10 Hz?

What do you suggest?

For LAME I know that is better JOINT STEREO but with iTUNES ENCODER?

Thanks

This post has been edited by Antigen: Apr 19 2012, 00:25

[[JAZ]]

10Hz Filtering: This is not a setting about improving efficiency or removing things that cannot be heard.

Generally, these types of filter are used to kill any DC offset that could exist in the signal. This should not exist in CD's but should not be strange at all with Vinyl rips or other analog sources. (Note: killing 50/60Hz Hum is acomplished with a notch band filter, which is not this case).
Said that, compression (as in dynamics) might also generate sub 10Hz "noise".


stereo/joint stereo and iTunes: I've heard several things about iTunes encoder. First, that it was the one that existed in the original software that Apple bought. Then, that it was an in-house version, then also that it was a derived version from frauhofer's encoder.

Said that, the sentences about using joint stereo at 128kbps and below, and stereo at 160Kbps and above come from before year 2000. The idea is that the more one lowers the bitrate, the more that joint stereo is needed. Not using it at higher bitrates had only sense in using less power or less complex selection algorithms on encoding (Remember MP3 was invented around 1994, and that originally, doing automatic switching between joint stereo and simple stereo like LAME, was not too common).

This post has been edited by [JAZ]: Apr 19 2012, 19:52