USB vs CD, BPM. CDJ2000

If you analyse tracks in Rekordbox it gives a stable BPM reading. Un-analysed tracks are done on the fly on the CDJ. When analysing on the fly - with CDs it seems to analyse the track much faster (noticed by the appearance of the waveform on display) , whereas with USB this is very slow - if you leave the track cue'd and paused it gets on building it. I suspect reading a raw WAV off the CD makes the analysing easier than decodiing an MP3 - you could try using WAVS instead of MP3s to try this out or just use RekordBox to pre-analyse.

All very interesting. Actually all the tracks I use are MP3's downloaded from BP. I've always burnt to CD before gigs. I just tested then and the MP3 off the CD doesn't give a waveform in advance. Only as it plays. Then I put in an actual bought CD and it reads the WAV in advance. Anyhow a friend just told me the other week that I'm kidding myself downloading MP3's when there's a WAV option. I'll download WAV's from now and use Rekordbox. And the journey begins. Cheers PaC

Just to let you know.  There is an AIFF option in beatport now.  Lossless.  And the next update in Rekordbox is supposed to be able to read the metadata from AIFF.  Much better than inputting all of the track information yourself with a .wav.  You'll just have to wait for update until you can see the information.

Also, yeah, analyze in RB first, also, USE NORMAL MODE to analyze, NOT DYNAMIC MODE.

Agree with the above comments.  It's best to use Rekordbox for analyzing your tracks before a gig.

That said, the true explanation for a changing BPM could be the music file itself.  Unfortunately, some tracks don't have a perfectly constant BPM.  As mentioned above, it is important to use the Normal Mode to analyze your tracks if they are constant BPM.  But sometimes a track that is supposed to be constant ends up having some minor fluctuation in the BPM.  This is usually an error in the production of the track.

When you encounter a fluctuating BPM in Rekordbox, you should try switching to Dynamic Mode and re-analyze.  You can then use the Beatgrid Adjustment to fix any drifts from the tempo.  Just keep in mind that Rekordbox does not have a warping engine like Ableton Live, so when you adjust the beatgrid you are just changing the measurement scale of the tempo.... not actually fixing the drift in the music.  If you do this, your tempo BPM reading on the CDJ player will change through the track's duration.

If you have an annoying track with a drifting tempo and want to fix it, then you could use a program like Ableton Live to warp the track to a constant BPM and then render it to a WAV.

Much appreciated. Thanks for the info. I'm an Aussie working full time in Sth Korea. Pushin ahead solo with Dj'in here in the evenings. I've been struggling without anybody to bounce ideas and issue's off. Glad to have found likeminded souls. Cheers.

@GodsDJ > As everyone has mentioned already... Yes you should use Rekordbox to analyze your tracks, and use the "Normal" setting to analyze, because the "Dynamic" setting does not apply to you with your BP collection. Also note that Rekordbox files are only recognized on the CDJ's via USB device or a computer running Rekordbox via LINK. By using Rekordbox and the LINK feature between capable CDJ's and DJM's, all your BPM's will be quantized and in sync with the latest firmware updates. The reason for fluctuating BPM would be the result of the CDJ trying to follow a tracks grid during a breakdown or something that is difficult to be precise. My 2000's have varied a little more than 1 BPM when using unanalyzed tracks for testing purposes so it's not uncommon. And yes, you can download WAVs from now on if you prefer. ;) But they will take up a lot more space on your hard drive just so you know ahead of time!

@Fuse Promote > I'm not sure how one would have a BPM error with a production when using 4/4 in a professional production application?

And sorry, but there isn't much point to render an MP3 to a WAV as it doesn't upgrade the quality or anything. If you have a personal preference for the WAV file type then it might make sense, but the quality of the track will always remain an MP3.

Thanks,

Foster 

@Foster -    I have been DJing for more than 10 years, and I can promise you that there have been tracks with errors in tempo.  It's a rather common problem.  I realize that with computer produced music it theoretically should not be happening, but I assure you it does.  I'm not sure why it happens.

Secondly, the only reason I said to render a track down to WAV from Ableton Live is because that's the only method the software allows you to do it.  I was making no reference to trying to improve the sound quality.  I know that cannot be done.   But, if you run into a faulty track with a shifting tempo and want to fix it.....  using a software program like Ableton Live may be the best option for repairing the tempo and rendering a new audio file which works correctly.

@Fuse Promote > I guess I'm just lucky to never have seen an error in tempo from a purchased track. A rip version or set rip I can completely understand, but I've never seen or purchase a track that has an altering tempo or where the beats are out of sync slightly.

My bad the Ableton thing, I use AIFF because it works more fluently with my system and forgot it only has 2 options. (I keep thinking my AIFF's are MP3's because of how my system treats the files alike, WAV is a little different for me). Anyways, still good to notify others upgrading audio quality isn't possible. But yes I agree, Live would probably be my choice of correcting tempo on a track if needed, although it's a hefty price tag just for that purpose in my opinion. Hopefully a friend could help someone out if they really needed it done for a couple tracks.

Thanks for your input mate,

Foster 

Just to follow up on this, yesterday I purchased some new AIFF music files from Beatport.  I decided to run them through Ableton Live as described in my previous post above.  I warped each track in Ableton (and by the way, every one of them had fluctuating tempo), and then rendered them to new AIFF files with constant tempo.  Then I imported the newly created audio files into Rekordbox and I was amazed at how much better the tempo is holding.  You can see the difference immediately in Rekordbox, as the tempo grid lines up perfectly with almost zero need for adjustment anywhere.

This will be my new procedure for all purchased music from now on.

@ fuse promote i have mp3 are the tempo adjustments also work in abelton with mp3 and wraped it out in to AIFF?

You can load any MP3 file into Ableton Live, but when you render the warped track it will be WAV or AIFF.