Tempo from Song

[Technog0d]

I was given a song with a bunch of stems to work with. The song is set to 140 bpm, but the stems do not seem to match the devision. meaning that if i take an individual audio track and look at the transients; they do not seem to match up with the tempo of the song. The question is...

What is the easiest way to figure out the tempo in order to have the stems match up to the song tempo. Or, vise versa.

Mike

[Holly73]

You could just highlight a bar (or a few of them) using Tab to Transient and then "identify beat". If ist was recorded to a metronome, maybe this is enough to find out the correct tempo of the song. Otherwise, just go through the whole song repeating these steps until the song matches the grid. This method doesn't change the tempo of the audio, but the grid resolution of the song.

Another way to do it: if you are on 7.4, you could use Elastic Time to match the audio to your existing grid.

[O.G. Killa]

Well, is it live performances? it could be that live performances vary from the grid a little. If the stems drift further and further out of time as time goes by...then there could be a few things wrong...

First, if these stems were used to create the 140bpm mix... then it could be you imported the audio incorrectly somehow, or the audio was exported incorrectly.

Second, as Holly73 pointed out you can do an "Identify Beat" to a few measures of the stems to see how far out they are from the original tempo.

Third, if you want to recreate the grid TO the stems, use Beat Detective, the tab "Bar|Beat Marker generation".

And as a side note, Holly73, I noticed in your signature you say "Elastic audio rocks! Lack of PDC doesn't!!!". Are you referring to Plugin Delay Compensation? PTLE has had Plugin Delay Compensation since Ver 6 at least. Possibly even in Ver 5.

[Holly73]

Originally Posted by O.G. Killa

And as a side note, Holly73, I noticed in your signature you say "Elastic audio rocks! Lack of PDC doesn't!!!". Are you referring to Plugin Delay Compensation? PTLE has had Plugin Delay Compensation since Ver 6 at least. Possibly even in Ver 5.

I'm sorry to say, but you are wrong. At least mine (7.4.2) doesn't.
There is lots of discussion about this and in the end the result alyways is: PTLE is one of the few DAWs nowadays that lacks it. Did you ever try to use some plugins like the UAD ones? Or some convolution plugins?

[O.G. Killa]

Ahhhh!!! that's where you are going wrong. ProtoolsLE DOES have PDC. Try this test for yourself...

Set your playback buffer to 1024. Take a stereo drum track (or any track for that matter, drums usually work best because you can hear the comb filtering in the cymbals easily), Bus it to an Aux track. Insert a BF76 plugin on it. Play them in parallel. You can even bypass the BF76 if you want. Mute and unmute the aux track... the drums just get 6 dB louder, no comb filtering. PTLE is compensating for the BF76 plugin AND the latency in bussing over to the aux.

NOW!!! do the same thing with a UAD 1176 inserted on the Aux. You can bypass it or leave it on. Mute and unmute the aux... can you hear the comb filtering?

All plugins need to announce how much latency they induce. If you hold down the Command key and click on the volume display for a track, it will toggle through Volume, Peak level, and Latency Delay (in samples). If a plugin incorrectly reports its delay, it will never be compensated for correctly.

The other reason the compensation might not work is if a plugin (like a convolution reverb plugin or a brickwall limter like an L3) creates SOOOO much delay that the Hardware Buffer size isn't big enough to allow for compensation. You'll notice the higher you set your H/W buffer, the more plugins will be compensated for. If you are using a buffer of 128K, only the most basic and DSP efficient plugins will be compensated for.

PTLE was one of the first DAWs to implement delay compensation right around when they switched from Ver 5 to Ver 6. PTLE had PDC long before HD every had ADC. I can remember years ago that was the big controversy of the time. All the HD users were complaining that PTLE had PDC, why couldn't they get something like that for HD!!! And I specifically remember posts from Digi engineering talking about how PDC is kind of "built in" their Native Mix Engine since it runs on the Host CPU and that they've been working on ADC for HD which would not only compensat for plugins but for hardware inserts and very advanced Mult'ing/routing schemes. PTLE has had it for soooo long they don't bother to list it as a "feature". Other programs like Logic and DP have just started adding it to the software in the last few years and so they try to list it as this big new feature.

The last time I did anything in PTLE that required PDC was in 7.3. I'll open up PTLE later today with 7.4 and confirm that it is still working. Unless something was broken from 7.3 to 7.4, it should work the same as it has since Ver 6.

[O.G. Killa]

OK, just verified it in my PTLE system running 7.4cs5 with an MBox2Pro. PDC is working, and it is compensating for the bussing latency as well.

[Holly73]

Ok, two possibilites:

1. I'm too stupid
2. There is no delay compensation.

I can't check it with the UAD now, because I'm not at my main system, but I tried it right now with a drum recording. Well it works with BF76, but PT reports 0 samples of delay anyway. The I tried Expander/Gate with look ahead enabled. Like this it has 88 samples and there is comb filtering.

[O.G. Killa]

The reason the Expander/Gate 3 doesn't work is because of the look ahead capability. In order for it to look ahead, it has to cache the audio. It is caching a larger amount of audio than your H/W buffer can compensate for...

Try using Comp/Limiter 3, or the De-esser 3, or drag dyn II back into your plugins folder and use the Exp/gate from that (it doesn't have look ahead), or Smack, or any other plugin that doesn't have look ahead. Try using a Waves RenComp, or Q10 or RenEQ4, etc... Your PDC is working.

And also, There is always latency from doing any type of DSP functions. But as your computer gets faster, the amount of samples it takes to do the computations gets smaller. When it is saying 0 dly, the delay is under 1 sample. On my old G4 iBook, the BF76 reports 4 samples of dly, on my newer 2.16 Dual Core Duo MacBook Pro it reports 0 samples.



As for the UAD stuff... that is a completely different animal because the DSP is done on the UAD card, not on the Host CPU, so the host will have problems trying to compensate. AND, UA never wrote an RTAS plugin, they use the VST to RTAS wrapper from FXpansion. So even if the UA card is reporting the correct amount of dsp delay there is no guarantee that the wrapper is.

[Holly73]

Originally Posted by O.G. Killa

The reason the Expander/Gate 3 doesn't work is because of the look ahead capability. In order for it to look ahead, it has to cache the audio. It is caching a larger amount of audio than your H/W buffer can compensate for...

But when it can't compensate for the 88 samples, it means it has no PDC. Systems with a working delay compensation just play all the other stuff 88 samples later.

Originally Posted by O.G. Killa

Try using Comp/Limiter 3, or the De-esser 3, or drag dyn II back into your plugins folder and use the Exp/gate from that (it doesn't have look ahead), or Smack

Well, these all report 0 samples, so there is no PDC necessary. What should it proof?

Originally Posted by O.G. Killa

As for the UAD stuff... that is a completely different animal because the DSP is done on the UAD card, not on the Host CPU, so the host will have problems trying to compensate.

According to your arguments, plugins with a delay below the value of the buffer settings are getting compensated for. This can't work for the UAD, as the audio needs to travel to the card and back. And the time it takes for this is always determined by the buffer settings in the host.

Here is something from the UAD manual:

[O.G. Killa]

UAD is saying the UAD card does not have PDC in the following programs... and if they wrote an RTAS version of the plugin instead of using a wrapper, Protools LE might be in the Full PDC catagory...

Pick another plugin that has a reported delay value... Smack on my system reports a delay value of 1 sample, yet there is no comb filtering. But if I take the drum track, duplicate it, and nudge the second one forward by 1 sample, you can really hear the comb filtering. If you have smack, put it on and see.

My point is, you are saying "Because these one or two plugins aren't compensated for, then there is no compensation being done at all..."

What I'm saying is, "because MOST of the plugins are compensated for, there is PDC being done, but there is something special about one or two that make them fall outside the abilities of PDC."