mp3 timing issues

[pushtobreak]

I just checked 2 identical files one mp3 and one wav. In Logic the files line up perfectly in phase. In Live the mp3 has a little more blank at the top and seems, in the 8 bars, to even be stretched out a tad!!! but it's hard to be sure it is quite small. In any case the timing is way off, flaming not phasing.

I need to test a longer file to be sure about the stretching issue...I can't believe I haven't heard more about this! Seems like it should be a big deal on a couple of fronts..1st is that I was hoping to use ref stems sent to me as mp3s to work on a project and now I am concerned about the timing of what I will send back. 2nd because it brings up the question of how accurate the mp3 conversion is. It seems like a timing issue should be easily fixable (and measured) and one of the obvious things to check for when creating a conversion process.

I realize there could be issues related to the mp3 type and sample rates but like I said the same files in Logic match exactly.

Is it just me? Anyone else seen or tried this? Am I missing something obvious?

Live 7.0.14

[longjohns]

do you have the latest quicktime installed?

[pushtobreak]

Just updated to the latest Quicktime. Still getting the same result.

[pushtobreak]

Longjohns, have you tried testing this on your system? I'm just curious if anyone else gets the same result.

[longjohns]

can't test now.

are the mp3's VBR?

[pushtobreak]

I didn't make the file. Here's the most info I can see for it:
MPEG audio file
Bit Rate: 256 kbps
Sample Rate: 44.1kHz
MPEG-1, Layer 3
Stereo
ID3 Tag: v2.2
Encoded with: iTunes 8.1.0.52

I'm not sure whether that means it's not VBR? I'll ask the person who sent it to me.

I'm bummed that Logic had no problem with the same files (it did take a bit longer for the files to be processed when loading them into Logic).

[pushtobreak]

Just did another quick test: AIF converted to mp3, top of the two files lined up on two tracks in Live. Looks like about 20ms extra blank space at the top of the converted file mp3/aif....but, one positive note is there doesn't appear to be any stretching as I thought I saw in the first test with the smaller file (That was 8 bars this test was with a 4 min track).

I converted this file to mp3 in iTunes 8.1, 192kbps

If it is the same amount of added space at the top each time it would be, at the very least, helpful to know that it exists and how much is added.

[Jesse]

Every different MP3 encoder out there puts a little bit of blank space at the beginning of the audio file once it's been converted, and every one puts a different amount of space at the beginning of the file. It's not a Live issue, but an issue with converting Aiff or Wav to MP3 in general. I'm not sure what you are converting to MP3 with, but I can say that LAME encoding is IMO the best way to go, and adds 52 Milliseconds to the beginning of a file, you'll need to move the start point and the warp markers by that much. Or just rewarp the file. But I assume you are doing multitrack stems. Warp at X BPM is your friend in this case, if you know the tempo of the files.

It caused me a lot of pain to figure that out, hope that info can help you. I'd also google the Lame encoder for iTunes, a great little applescript. Hydrogenaudio.com is a good place to refer to for MP3 issues.
Best,
Jesse

[pushtobreak]

Thanks, that is really helpful. I'll check out the LAME encoder. I'm still not sure why the same files worked perfectly in Logic. I guess either Logic compensates for the blank somehow or is the blank only added on the reconversion from mp3 back to Aif? I'm pretty sure Logic is using the mp3 directly and Live is converting it back to Aif from what I understand.

This should really be made more common knowledge somehow. Even if it's not Live's fault it would be nice to get a heads up in the manual or somewhere. (I probably would have missed that anyway :/)

[elektrische]

coding to mp3 is a cool possibility although has a one huge disadvantage. whenever coding files to this kind of files expect little EMPTY BREAKS (queit pausas) in the beginning and the end of every file. sometimes to align mp3 and wavs u will have to warp the mp3 first.
wma files seem to be a solution for that because +/- they are similar size to mp3.
ableton 7 doesnt allow using wma though. dont know how it works with 8.