hello
i’m using the gain automation tool to add gain envelopes directly to different tracks. all my regions are normalised to 0 db, but when the gain envelope is also at 0 db i am getting clipping in the mixer. this doesn’t make sense to me.
can anyone tell me how what is going on here?
thanks for any help!
Are you mixing music or doing a theoretical test?
MIXING
Which of the track or buss is reporting > 0 db signal? If you have “clipping” then one of those stages is clipping or the signal to a DAC is too hot for the converter.
In practical application the amount of noise in digital equipment interfaces like the rme9652 is very low when compared with analog tape machines. The upshot is that you don’t need to push the signal level above the noise level like all of us did back in the tape machine days. Don’t push your levels.
There’s no reason to achieve levels near 0db in the stereo bus or subsequently in the stereo mix during recording and mixing. That doesn’t become a concern until mastering and then it’s not achieved with the use of normalization.
To make up a scenario where I’d normalize, I never have, let’s say one instrument track is at < 0.1 while the other is < 35. Normalizing the < 35 instrument track would enable a more comfortable mixing scenario where the faders are at similar levels.
THEORETICAL
Not my area of expertise and I know nothing about how Ardour manages summing in its busses.
I have no idea whether any of my diatribe answers your questions but it’s fun to try and look smart. 
Ron Parker
Mirror Image Studio
from a previous post i read:
“They are just two different gain stages. The gain envelope affects the gain of the signal coming from the “diskstream” to the track, so it is effectively “pre-pre-fader” gain. The gain automation affects the tracks’ gain, which is between “pre-fader” and “post-fader” redirects (meaning plugins, sends, inserts, etc.).”
to me, this means using the gain envelope (“pre-pre-fader”) set to 0 db on a track which has also been normalised to 0 db (which is what i’m doing) shouldn’t result in that track going into the red, which is, of course, something i’d like to avoid.
jaskah if the track is the only thing going into the red I wouldn’t worry about it at all, the only place you are actually going to ‘clip’ is in the final DA stage, typically the ifnal output out of Ardour.
If the region is normalized to 0dB, and the region gain is at unity then your file will hit 0dB, which in terms of dBFS is the highest point any audio will reach whether it be clipping or just being there, there isn’t a good way to differentiate on a dBFS scale whether a clip occurred, or whether you just hit 0dBFS.
All of this is moot because in Ardour/Jack you won’t actually clip until a DA stage. You could drive your track to +30dB and be fine so long as that isn’t the metering right before a DA stage.
Seabladehi seeblade
thanks very much for your response. so, if understand you correctly, clipping in individual tracks is nothing to worry about but clipping at the master bus would be the problem? (i always avoid clipping in the master bus)
it’s written in the floss manual that even clipping on individual tracks should be avoided:
http://en.flossmanuals.net/Ardour/Mixing
but what i still don’t understand: why is there clipping when the envelope is at 0 db and the region itself is normalised to 0 db? this doesn’t make sense to me. if i were setting the envelope above 0 db on the same normalised region, then i could understand clipping happening, but as it is, with a 0 db envelope peak there should be no way that the region exceeds 0 db and clips.
“so, if understand you correctly, clipping in individual tracks is nothing to worry about but clipping at the master bus would be the problem?” There is no good reason to push the Master buss towards 0 until Mastering when you would probably have a brickwall limiter absolutely prevent > 0. Exceeding 0 at the instrument channel will cause the master buss to ouput > 0 and thus clip the DAC.
The short answer to your question is that you should worry about exceeding 0 in the tracks.
The answer to your question is just a bit lower than what you were reading I think… quoted from that page…
Because Ardour uses Floating Point Numbers internally, signals are not necessarily Clipping as long as the information remains within Ardour. So it may be OK if a track or bus occasionally turns red. But you should make sure that anything that you send to your sound card or that you will eventually Export as a sound file (such as for CD mastering) never goes above 0.0dB to avoid actual Clipping.
Seabladehi seablade
thanks again for your response.
So it may be OK if a track or bus occasionally turns red. But you should make sure that anything that you send to your sound card or that you will eventually Export as a sound file (such as for CD mastering) never goes above 0.0dB to avoid actual Clipping.
so, i guess when they are saying here that whatever i send to my sound card doesn’t go above 0.0db they are referring to the master bus never going above 0.0 db?
but what i still don’t understand is why, when i have a region with maximum peak at 0.0 db and a gain envelope set at 0.0 db, that the track goes into the red. many years ago i used to work with logic and this was not the case. ok, now it seems clear to me that, due to floating point calculation in ardour, tracks going into the red don’t necessarily mean distortion, but it is still somewhat mysterious why they go into the red at all if i am not pushing them above 0.0 db with the gain envelope.
i’m not trying to be pedantic here, i’d just like to understand how, in this respect, ardour is working. it’s a bit worrying seeing all these tracks going in the red when i haven’t pushed them there!
My guess without seeing exactly what you are seeing is that the arbitrary point chosen for ‘red’ in Ardour is lower than for Logic, in this case it is -0.1 or thereabouts instead of over 0.0 would be a completely shot in the dark guess. I know clip detection on the imported soundfiles has a similar setup where often times when I import other recordings it will show clipping even if it really isn’t because of how hot in the recording those peaks are.
SeabladeArdour uses the logic “if an audio sample is equal to or greater than 0dFS then draw a clip indication”.
The operation of “normalizing” a region means that the level of the region is adjusted so that the loudest sample(s) is exactly 0dBFS. So any region will show at least one clip line after a normalize, and assuming no region gain or other level changes it will register as a clip on any meters that it plays through.
The choice of how/when to draw a clip indication is complicated, and has changed over the years.
In your case, it probably doesn’t mean anything and can be ignored (except, as noted, when you are looking at the master output meters. In this case you should be extra-sensitive to clipping.)
Best,
Ben Loftis
Harrison Consoles
I’ll second rtp405, you don’t need to be normalising your tracks unless you’re expressly trying to make a too-soft track louder. From reading your posts, jaskah, I get the impression you are making the situation too complicated. You’d probably be better off mixing at whatever level the tracks were recorded, unless that level is far below normal.
thanks again to everyone who replied to this thread. this has been very helpful.
Ardour uses the logic "if an audio sample is equal to or greater than 0dFS then draw a clip indication"... In your case, it probably doesn't mean anything and can be ignored (except, as noted, when you are looking at the master output meters. In this case you should be extra-sensitive to clipping.)
i think this explanation pretty much solves the problem of trying to understand why these tracks are clipping.
you don't need to be normalising your tracks unless you're expressly trying to make a too-soft track louder.
this is exactly what i’m doing; i’m not mixing a multi-track recording with different tracks of instruments (guitar, bass, whatever), rather, composing from different sound files, some of which are excerpts taken from longer recordings and hence not always as loud as i would like them to be. i like to start with all the files i work with at normalised levels and then adjust their relative levels with volume envelopes.
hi rtp405
thanks for your reply.
Exceeding 0 at the instrument channel will cause the master buss to ouput > 0 and thus clip the DAC.
but if the master buss is set below 0 then there will be no distortion, right?
basically, what i’m up against now is having a mix where, in some tracks, there are peaks which are going into the red (even though these peaks have actually been normalised to 0 db and the track’s gain envelope is at around -1.0 (and i still don’t understand how this can be clipping).
in order to avoid having to reduce all the volumes of these peaks with laborious gain envelope work, i’d just as soon leave the track alone, if i could know for sure whether this track will be distorting in the final mix (i can’t hear any distortion) when the master buss is set below 0.