Render Quality issue

chuskey · Post by **chuskey** » Wed Jul 30, 2008 4:24 am

I've recorded a simple 8 bar loop with four audio tracks. I recorded it at 48k/24 bit. I'm rendering it to 44.1k/16 bit to import it onto a Boss RC-50.

I noticed once it was rendered that the sound quality was not good. It's hard to describe, but it had sort of a "warbling" sound if that makes sense. Almost like when you try to change the tempo of a track too much it messes with the sound quality.

After trying different options I dropped the wav files directly into Garageband without rendering. I then created a mix of the same tracks and the sound quality was fine. It didn't lose any quality.

I'm running Live 6.0.10 on a Macbook Pro with Presonus Firepod as the interface.

Any ideas on why Live is rendering poorly?

Thanks.

leedsquietman · Post by **leedsquietman** » Wed Jul 30, 2008 4:55 am

Did you warp any tracks ? If so, which warp mode did you use ?

What are your levels like ? If you are clipping this can cause such problems.

What processing did you apply. Too much compression/limiting can cause these problems.

Why are you recording 24/48? That requires a sample rate conversion as well as DITHERING. I only record 48 Khz if I am making audio for video, which typically runs at that sample rate.

Which dithering algorithm (if any) did you use?

Did you try reimporting the 16 bit/44.1 files into Live ? You only mention trying to import into the Boss RC50. How do the files compare with Garageband?

Live's rendering is equally as good as anything out there, so there must be a problem somewhere in your mastering chain, quite possibly due to one or more of the above issues.

Remember - when you are monitoring in 24 bit mode, you get 12db more headroom, so you can run your mixes into the red a few db over 0db and not hear the clipping, but in the 16 bit world of CD and mp3, you go over 0db, you get digital overs 'clipping' which can wither make your mixes sound udll and lifeless and/or cause digital distortion.

chuskey · Post by **chuskey** » Wed Jul 30, 2008 1:19 pm

leedsquietman wrote:Did you warp any tracks ? If so, which warp mode did you use ?

What are your levels like ? If you are clipping this can cause such problems.

What processing did you apply. Too much compression/limiting can cause these problems.

Why are you recording 24/48? That requires a sample rate conversion as well as DITHERING. I only record 48 Khz if I am making audio for video, which typically runs at that sample rate.

Which dithering algorithm (if any) did you use?

Did you try reimporting the 16 bit/44.1 files into Live ? You only mention trying to import into the Boss RC50. How do the files compare with Garageband?

Live's rendering is equally as good as anything out there, so there must be a problem somewhere in your mastering chain, quite possibly due to one or more of the above issues.

Remember - when you are monitoring in 24 bit mode, you get 12db more headroom, so you can run your mixes into the red a few db over 0db and not hear the clipping, but in the 16 bit world of CD and mp3, you go over 0db, you get digital overs 'clipping' which can wither make your mixes sound udll and lifeless and/or cause digital distortion.

Thanks so much for the informative response! I guess I was recording at 24/48 thinking I should start with the best quality, but that makes sense to start at 16/44.1, especially since I know that's where it will end up.

The tracks are warped/looped, but only to set the start and stop points. I haven't made any adjustments to where the beats are inside of the loop. They are all set to "tones".

I kept the levels up fairly high, but there was no clipping I made sure of that. I could try bringing them down a little.

I have a Line6 gearbox plug in on one track, and some compression on another. The other two don't have any plug ins. I have Ableton's reverb on Send A. Nothing on the master track. I'm pretty sure I tried rendering without the Line6 plug in turned on though just to check if it was that.

I didn't run any dithering algorithm. I simply used the render to disk option in Ableton. And I didn't try re importing the files.

I guess one of the things that was puzzling to me was that Garageband took the same tracks and I didn't get those issues. I guess that could lead me to believe it was a plug in or warping, but it's not like I'm pushing the limits of what it can do.

Tonight I'll go through and try your suggestions and see what I come up with. If you see anything in the info I've given here please let me know what I might be doing wrong.

Thanks again!

laird · Post by **laird** » Wed Jul 30, 2008 4:45 pm

If you adjust the start and stop points in a clip, and set it to "tones", then yes you could be applying some time stretching to that audio file. And, yes, time stretching can create a warbling sound, even if the bpm remains fixed.

"Tones" mode is best for, well, tones. Not songs, not beats.

For the best quality, either turn Warp off, or set it to Beats mode and make no bpm adjustments. Any other mode makes changes to your audio, however small.

Still, Rendering usually won't make the .wav file sound different from your Live file. LQM brings up some ways you CAN make it different. Clipping (any red on the master fader?). Sample rate adjustments (48 khz to 44.1khz).

In the future, record at 24/44.1 or 16/44.1 and you can avoid sample rate conversion issues.

chuskey · Post by **chuskey** » Wed Jul 30, 2008 11:23 pm

laird wrote:If you adjust the start and stop points in a clip, and set it to "tones", then yes you could be applying some time stretching to that audio file. And, yes, time stretching can create a warbling sound, even if the bpm remains fixed.

"Tones" mode is best for, well, tones. Not songs, not beats.

For the best quality, either turn Warp off, or set it to Beats mode and make no bpm adjustments. Any other mode makes changes to your audio, however small.

Still, Rendering usually won't make the .wav file sound different from your Live file. LQM brings up some ways you CAN make it different. Clipping (any red on the master fader?). Sample rate adjustments (48 khz to 44.1khz).

In the future, record at 24/44.1 or 16/44.1 and you can avoid sample rate conversion issues.

I think I've got things somewhat sorted out. I set the sample to hi-q which seemed to help some. Oddly enough the worst results were leaving it at 24/48.

I think I may have found a glitch though that was causing my headaches. I was saving the file as the same file name each time. I noticed after I muted some of the tracks that after rendering it again the changes didn't happen. I had to rename the file before the changes I made were reflected.

So I'm wondering if I had actually fixed the problem for the most part last night, but because I didn't rename the file I kept getting the same result.

Frustrating.

Thanks again for the help. My sanity is now once again intact