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Gear / Technical Help => Ask The Tapers => Topic started by: mikesalvo on January 25, 2010, 12:31:18 PM
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so, last week I ran one mono SBD line (XLR left) and i ran one mic (XLR right) into my UA-5. there was a small bit of lantency between the sources. I have mixed a sample down to 2 tracks, If anyone has a sec to check it out, and see if its on or not. Seems like it is to me, but I think Ive listened to it to many times, and Im starting to go a lil cuckoo!
linky: http://www.megaupload.com/?d=JJEPYR16
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Have you tried stretching one of the sources to match the other in a program like Vegas? It's really easy to do and I would try it myself with your files except that I'm at work right now.
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so, last week I ran one mono SBD line (XLR left) and i ran one mic (XLR right) into my UA-5. there was a small bit of lantency between the sources. I have mixed a sample down to 2 tracks, If anyone has a sec to check it out, and see if its on or not. Seems like it is to me, but I think Ive listened to it to many times, and Im starting to go a lil cuckoo!
linky: http://www.megaupload.com/?d=JJEPYR16
FWIW I just posted a related question in "Computer Related Help" that might interest you.
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Have you tried stretching one of the sources to match the other in a program like Vegas? It's really easy to do and I would try it myself with your files except that I'm at work right now.
im using Audacity. I stretched the sources out.I think theyre fine. Just need a second opinion. its one of those things, where I have listened to it so many times, that i cant anymore. the wave forms look fine, but like I said, just need a second opinion...
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so, last week I ran one mono SBD line (XLR left) and i ran one mic (XLR right) into my UA-5. there was a small bit of lantency between the sources. I have mixed a sample down to 2 tracks, If anyone has a sec to check it out, and see if its on or not. Seems like it is to me, but I think Ive listened to it to many times, and Im starting to go a lil cuckoo!
linky: http://www.megaupload.com/?d=JJEPYR16
I am at work also but I would say if your mic was more then 20' away from the stage you will need to stretch. The easiest way to tell (a least for me) is to listen to banter from the singer and listen for reverb or pick a lone cymbal hit and see if the timing is right ;)
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im using Audacity. I stretched the sources out.I think theyre fine. Just need a second opinion. its one of those things, where I have listened to it so many times, that i cant anymore. the wave forms look fine, but like I said, just need a second opinion...
Oh I see, yeah I've been in that situation a lot before. The best way to be sure, in a really OCD way, is to check periodically throughout a show for single snare drum beats or better yet, the drummer 'timing intros' where he hits the sticks together (click click click click) at the start of a song. Those will almost always be off if it's not timed properly and are great to use because they tend to be isolated sounds before the song starts. If you check those in the beginning, middle, and end, and they're all perfectly single clicks, then you are good to go. Timing with other sounds works too but is less precise, in my experience.
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im using Audacity. I stretched the sources out.I think theyre fine. Just need a second opinion. its one of those things, where I have listened to it so many times, that i cant anymore. the wave forms look fine, but like I said, just need a second opinion...
Oh I see, yeah I've been in that situation a lot before. The best way to be sure, in a really OCD way, is to check periodically throughout a show for single snare drum beats or better yet, the drummer 'timing intros' where he hits the sticks together (click click click click). Those will almost always be off if it's not timed properly and are great to use because they tend to be isolated sounds before the song starts. If you check those in the beginning, middle, and end, and they're all perfectly single clicks, then you are good to go. Timing with other sounds works too but is less precise, in my experience.
you beat me to it by seconds... drum cracks are what I base most of my timings off of when doing post-mixes.
If they both ran into a UA-5, why stretch and not just shift? They should be all on the same clock which is the big problem related to stretching/shrinking. If it's just delay, then shift it.
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IMO it doesn't require mega-close listening. If you hear extra reverb in the mixdown, the sources aren't aligned well enough. If you don't then you've aligned them well enough to do the final mixdown. One of the key points here is that all of our ambient recordings have some amount of natural decay that's caused by the room. If your mixdown is tight enough that it doesn't sound like there's any more added reverb caused by the two sources being out of synch...any more than was already there because of the room, then you're there!
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im using Audacity. I stretched the sources out.I think theyre fine. Just need a second opinion. its one of those things, where I have listened to it so many times, that i cant anymore. the wave forms look fine, but like I said, just need a second opinion...
Oh I see, yeah I've been in that situation a lot before. The best way to be sure, in a really OCD way, is to check periodically throughout a show for single snare drum beats or better yet, the drummer 'timing intros' where he hits the sticks together (click click click click). Those will almost always be off if it's not timed properly and are great to use because they tend to be isolated sounds before the song starts. If you check those in the beginning, middle, and end, and they're all perfectly single clicks, then you are good to go. Timing with other sounds works too but is less precise, in my experience.
you beat me to it by seconds... drum cracks are what I base most of my timings off of when doing post-mixes.
If they both ran into a UA-5, why stretch and not just shift? They should be all on the same clock which is the big problem related to stretching/shrinking. If it's just delay, then shift it.
He must not have been running two bitbuckets on the output, or perhaps one source was from the digital outs and one from analog.
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Forgive me if I've got this wrong, but you do know how to sync the recordings and are just looking for someone to listen to it with fresh ears to see if it sounds right. Unfortunately I don't have the ability to download the sample and listen to it, but hopefully someone will just give it a listen and verify that you've got it right. Good luck.
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Forgive me if I've got this wrong, but you do know how to sync the recordings and are just looking for someone to listen to it with fresh ears to see if it sounds right. Unfortunately I don't have the ability to download the sample and listen to it, but hopefully someone will just give it a listen and verify that you've got it right. Good luck.
No...I think you've got it right. But on ts.com we like to talk about it for six or seven pages first. Listening in order to resolve this in one or two responses is just too easy. ;) :D ;) :P
LOL...I'm at work too and I'm blocked from sites such as megaupload.
Q: How many tapers does it take to get a Phish show recorded.
A: 100...one to make the first source that gets torrented exactly 5 minutes after the show ends (which 10 million people download from that point forward) and 99 others from the people that actually sleep at night.
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If they both ran into a UA-5, why stretch and not just shift? They should be all on the same clock which is the big problem related to stretching/shrinking. If it's just delay, then shift it.
^ what he said. Unless two different recorders were used to capture, with two different internal clocks, you should NEVER stretch...only shift.
There will always be some delay between SBD and AUD tracks, even if the mics were on stage, due to the differences in distance between the AUD mics and the sound sources and the inputs/mics used by the FOH engineer and sound sources. The direct inputs will be at the speed of electricity and stage mics used by the FOH will be within an inch or two of the sound sources for the SBD feed, while even stage lip mics will be a minimum of a few feet from any sound source and room mics much further back. This delay is corrected by shifting the SBD track(s) later in time until they match up with the AUD track(s).
Drift ALWAYS occurs (though it may be minimal in rare cases and not need correction) when you use two different digital recorders with different internal clocks that are not synced together. The different clocks have a slightly different a level of accuracy in keeping time, and that difference results in increasing delay at a constant rate over the course of a recorded track. Stretching one of the sources is the best way to accurately correct the delay that results from the drift between the clocks. The chop and re-align approach many use is sloppy and inaccurate, and does not actually fix the delay at the end of each chopped segment. This results in the end of tracks being off, and parts being potentially out of phase with comb filtering effects as the drift of the clocks brings the two sources out of sync during the course of each segment.
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I learned a lot from this thread that I was never quite clear on (thanks!), especially that I should be in the market for a 744T. :P
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I learned a lot from this thread that I was never quite clear on (thanks!), especially that I should be in the market for a 744T. :P
Or make friends with folks who have 702/722s (cause you can easily slave the other unit off of your clock to eliminate any clocking inconsistancies).
Thats the real benefit of having a Word clock IN/OUT and bit-perfect digital connections (or ability to pull a SPDIF signal and interpret it as though it were a Word Clock signal). If you don't, then when you join 3 recorders together and 1 of them resamples a digital in based on it's internal clock, then recorders A and B will be mixable, but recorder C won't cause it's material is off of a seperate clock. Thats when you get into stretching and all sorts of other tricks to get it to work. If you used C as the master, and slaved off of it, then pending a seriously poor designed output, all three would be accurate in relationship to each other.
Forgive me if I've got this wrong, but you do know how to sync the recordings and are just looking for someone to listen to it with fresh ears to see if it sounds right. Unfortunately I don't have the ability to download the sample and listen to it, but hopefully someone will just give it a listen and verify that you've got it right. Good luck.
No...I think you've got it right. But on ts.com we like to talk about it for six or seven pages first. Listening in order to resolve this in one or two responses is just too easy. ;) :D ;) :P
qft
He must not have been running two bitbuckets on the output, or perhaps one source was from the digital outs and one from analog.
I swear he said he ran 1 channel as sbd and 1 as audience through a single UA-5.
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so, last week I ran one mono SBD line (XLR left) and i ran one mic (XLR right) into my UA-5.
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Drift ALWAYS occurs (though it may be minimal in rare cases and not need correction) when you use two different digital recorders with different internal clocks that are not synced together.
In general, I agree with the overall advice, and there is a lot of good info in this post. But drift isn't always from two different clocks. Drift also can occur due to the difference between the speed of electrons (constant practically speaking) and the speed of sound, which varies.
The speed of sound is dependent on temperature and humidity, so the inherent time lag between sources (in milliseconds) could be different early on in a set in a cold, uncrowded club compared to later in the set with a croweded, hot, sweaty, humid club -- leading to drift later in the set even if the clocking is the same and the the two sources were synced at the outset of the recording. Generally, this probably isn't worth accounting for since it would have too great of an effect, but the OCD might want to re-sync periodically throughout the show or time-stretch (or better yet figure out exactly where the club is heating up and accelerating the speed of sound and time stretch only during that period).
Overall, differences in clock timing is probably the biggest effect leading to drift (at least for solid state recorders -- I think slight variances in DAT tape speed was probably a much bigger issue back when), but changes in the speed of sound can also lead to drift.
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Overall, differences in clock timing is probably the biggest effect leading to drift (at least for solid state recorders -- I think slight variances in DAT tape speed was probably a much bigger issue back when), but changes in the speed of sound can also lead to drift.
Maybe that explains why I had an impossible time with one show, trying to stretch two sources to perfectly match. I spent some two hours trying to get the drum stick clicks to perfectly match but it was impossible and I gave up eventually and ended up just deleting them (the drum stick clicks) and it sounds fine. :P
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He must not have been running two bitbuckets on the output, or perhaps one source was from the digital outs and one from analog.
I swear he said he ran 1 channel as sbd and 1 as audience through a single UA-5.
Oops, I missed that. Sorry, was thinking there were two sets of sources.
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im using Audacity. I stretched the sources out.I think theyre fine. Just need a second opinion. its one of those things, where I have listened to it so many times, that i cant anymore. the wave forms look fine, but like I said, just need a second opinion...
Oh I see, yeah I've been in that situation a lot before. The best way to be sure, in a really OCD way, is to check periodically throughout a show for single snare drum beats or better yet, the drummer 'timing intros' where he hits the sticks together (click click click click) at the start of a song. Those will almost always be off if it's not timed properly and are great to use because they tend to be isolated sounds before the song starts. If you check those in the beginning, middle, and end, and they're all perfectly single clicks, then you are good to go. Timing with other sounds works too but is less precise, in my experience.
another problem i have run into which makes it even trickier is when the SBD itself has some natural echo on it. then even a perfect matrix will naturally have some amount of echo to it of course, but it gets really difficult to tell how much echo constitues the 'right' amount from the natural echo only with the sources being perfectly in sync, and how much constitutes too much echo with some extra entering in from a slightly off sync job.
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Drift ALWAYS occurs (though it may be minimal in rare cases and not need correction) when you use two different digital recorders with different internal clocks that are not synced together.
But drift isn't always from two different clocks. Drift also can occur due to the difference between the speed of electrons (constant practically speaking) and the speed of sound, which varies.
The speed of sound is dependent on temperature and humidity, so the inherent time lag between sources (in milliseconds) could be different early on in a set in a cold, uncrowded club compared to later in the set with a croweded, hot, sweaty, humid club -- leading to drift later in the set even if the clocking is the same and the the two sources were synced at the outset of the recording. Generally, this probably isn't worth accounting for since it would have too great of an effect, but the OCD might want to re-sync periodically throughout the show or time-stretch (or better yet figure out exactly where the club is heating up and accelerating the speed of sound and time stretch only during that period).
You're right that changing environmental conditions will affect how sound travels in space, and thus the AUD/mic feed.
In my experience, however, the amount of that change has always been negligible and I have never felt a need to correct for it - particularly when the SBD and AUD tracks I recorded were clock-synced when captured. So, for practical purposes, I believe it is a reasonable operating principle that drift between two non-synced digitally recorded sources will be constant over time, due to the different internal clocks, and that environmental factors are negligible.
One example where there was significant environmental change, but no noticeable drift from those environmental factors, was a PBS set I recorded at Joshua Tree Music Festival last May. The set began a half hour before sunset and ended in the dark. The air temp. was probably ~ 100 deg. and there were not too many people at the beginning of the set. By the end of the set, air temp. had probably dropped at least 25 deg. to the mid 70s. A lot more people also filled in the concert bowl area as the sun dropped. Humidity was pretty constant - bone dry. I shifted and aligned the SBD tracks to the AUD tracks, but found no noticeable drift over the course of the recording.
http://www.archive.org/details/pbs2009-05-16.matrix.flac16
I could see where you might get something more noticeable in conditions like the summer in the SF bay area, when warm and drier daytime conditions change to more humid and colder temperatures as the fog rolls in with the sunset. But, I think you'd need to have something like significant change in environmental factors coupled with an Allman Bros.-like 3+ hour long set before drift from any environmental factors becomes noticeable.
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Yep, totally agreed that temp/speed of sound related drift is pretty negligible and can be ignored. I can't imagine even with extreme changes it would affect things by more than 5-6ms -- just enough to drive the OCD a bit crazy, but no practical/discernible difference.
Just getting it out there that there are other sources of drift. The matrixes I did back when I ran DAT were far more difficult, even compared to doing matrixes of non-clock synced sources from solid state recorders. Maybe the clocks were just that much more variable on older DAT decks compared to the newer decks, but it always seemed to me that it must be that variable tape speed was a big issue for drift. Who knows? Maybe someone out there with a V3 with a WC out and a Mytek with a WC in, and two old DAT decks can test out the theory for me. :D