how did logic compare to vox with the same file format?
Is VOX bit-perfect?
Brett,
If You need accuracy - use Logic. Vox does not pretend to be a professional production software. I will also research into what You show here, because I think how we can improve Vox also...
Also please make sure that there is no additional gain applied in Vox.
About inaccuracies in audio data in Vox: they are the same as in any 32-bit floating point audio software. seems the level is what is different here.
Anyway, thank You for Your educated analysis.
Anonymous
#11
Ok, I didn’t screw anything up. Below are the results of the same file measured in Logic. They are both the same - one is with Apple Lossless and the other WAV. you can see the source sample clips are 0, which accurately reflects the actual file. also notice they are the same, as they should be.
So VOX is doing something funky.
If you want me to test anything in the future please let me know. I will use Logic from now on.
Also, note, that Fidelia also reports similar inaccuracies although the results are different than VOX.
I assumed “bit perfect” meant “bit perfect” but I guess we are using different definitions of “perfect” :) I would encourage you to not tout VOX as bit-perfect unless its actually bit-perfect. :)
Brett
On Dec 22, 2016, at 2:41 PM, UsabilityNow brett@usabilitynow.ca wrote:
I might have screwed something up… stay tuned…
On Dec 22, 2016, at 2:37 PM, soundguy > wrote:
VOX_Support_Team
#12
Well, Brett, that's serious statement. I will try to
compete.
Here are my 2 cents, to be more precise, two pics.
I don't own Logic Pro but I have Reaper.
My conditions were:
all tests in 44.1 kHz SR, no sample rate conversion
No other plugins or effects in use
The same WAV track rendered fully up to last 18 seconds of fadeout
once while taking roundtrip clipping measurement in both cases
All volumes are unity, no other processing anywhere.
Please tell me what am I doing wrong that my readings of "source" are identical?
Anonymous
#15
Perhaps there is something going on specific to my system that causes VOX to add gain. let me try some things.
VOX_Support_Team
#16
First, try removing other AU's from chain - leave just one that You are measuring with. Don't just bypass others, delete them.
Anonymous
#17
I also run Audio Hijack and Audio Mate which I will disable and reboot. I will do each step and then a test to see if one of those is affecting things.
VOX_Support_Team
#18
This is pink noise at -3.5 dB test, to exclude the possibility of clipping and to show that Vox doesn't do any tricks with levels:
Anonymous
#19
I found the problem. sample rate conversion. if there are any inputs or outputs in “audio midi” with sample rates other than the file sample rate, sample rate conversion (within VOX?) will cause RoundTrip to report sample clops.
I use Audio Hijack as well. if Audio Midi is set to the right sample rate, it may be that Audio Hijack i(AH) isn’t. AH doesn’t seem to change it’s sample rate once set from initial launch. so if the file rate is 44.1 and the system rates are all 44.1 there will be no sample clipping.
It appears to be s simple sample rate conversion issue. as long as I ensure the output I am using is set to the file rate, there are no sample clips.
I discovered that a track has to be re-started by double-cliking on it if the system sample rate has changed otherwise the file will continue playing at the previous set rate when it was first played.
“Syncronize sample rate with player” helps to solve this problem by forcing the system rate to the file rate. this seems to work.
WHEW! :D
Anonymous
#20
So an area where VOX could be improved is an honest better sample rate conversion. it’s easy to not know if the sample rate “chain” isn’t creating problems because of rate conversion, because a lot of what goes on is under the hood. but it seems like VOX can essentially control the same rate of the system. so both a better quality sample rate conversion and some kind of warning that its doing conversion would be great. that way the user can be alerted to a problem and resolve it.
just a suggestion based on all our troubleshooting
brett
On Dec 22, 2016, at 5:42 PM, UsabilityNow brett@usabilitynow.ca wrote:
I found the problem. sample rate conversion. if there are any inputs or outputs in “audio midi” with sample rates other than the file sample rate, sample rate conversion (within VOX?) will cause RoundTrip to report sample clops.
I use Audio Hijack as well. if Audio Midi is set to the right sample rate, it may be that Audio Hijack i(AH) isn’t. AH doesn’t seem to change it’s sample rate once set from initial launch. so if the file rate is 44.1 and the system rates are all 44.1 there will be no sample clipping.
It appears to be s simple sample rate conversion issue. as long as I ensure the output I am using is set to the file rate, there are no sample clips.
I discovered that a track has to be re-started by double-cliking on it if the system sample rate has changed otherwise the file will continue playing at the previous set rate when it was first played.
“Syncronize sample rate with player” helps to solve this problem by forcing the system rate to the file rate. this seems to work.
WHEW! :D
On Dec 22, 2016, at 4:49 PM, soundguy > wrote:
Anonymous
#21
Here is something else Ive notices: when VOX is doing sample rate conversion (where the rate of the file is different than the rate of the system) when a new track is started it will play a small amount of the previous tracks’ audio as if its stuck in a cache. this causes problems because its annoying but also because it triggers meters. as you know I use VOX to play back files to analyze them with meters (that’s a compliment). so when this clip plays it throws off my meters. when the file and system rate are the same, this small amount of the previous track doesn’t play.
brett
On Dec 22, 2016, at 10:34 PM, UsabilityNow brett@usabilitynow.ca wrote:
So an area where VOX could be improved is an honest better sample rate conversion. it’s easy to not know if the sample rate “chain” isn’t creating problems because of rate conversion, because a lot of what goes on is under the hood. but it seems like VOX can essentially control the same rate of the system. so both a better quality sample rate conversion and some kind of warning that its doing conversion would be great. that way the user can be alerted to a problem and resolve it.
just a suggestion based on all our troubleshooting
brett
On Dec 22, 2016, at 5:42 PM, UsabilityNow > wrote:
I found the problem. sample rate conversion. if there are any inputs or outputs in “audio midi” with sample rates other than the file sample rate, sample rate conversion (within VOX?) will cause RoundTrip to report sample clops.
I use Audio Hijack as well. if Audio Midi is set to the right sample rate, it may be that Audio Hijack i(AH) isn’t. AH doesn’t seem to change it’s sample rate once set from initial launch. so if the file rate is 44.1 and the system rates are all 44.1 there will be no sample clipping.
It appears to be s simple sample rate conversion issue. as long as I ensure the output I am using is set to the file rate, there are no sample clips.
I discovered that a track has to be re-started by double-cliking on it if the system sample rate has changed otherwise the file will continue playing at the previous set rate when it was first played.
“Syncronize sample rate with player” helps to solve this problem by forcing the system rate to the file rate. this seems to work.
WHEW! :D
On Dec 22, 2016, at 4:49 PM, soundguy > wrote:
VOX_Support_Team
#22
Please specify sample rates of source and output when You noticed clipping bump?
VOX_Support_Team
#24
I measured the same file with SR conversion from 44.1 to 88.2 and level rise is around 0.2 dB - which is normal since SRC is taking place. We are prepping new major version update (not very soon) where there will be a pack of deeper Hi-Res settings among which is a choice of SRC params
But I don't believe that more sophisticated SRC type will eliminate this level bump radically - because no matter the exact algorithm, to do SRC You need to antialias, which in turn may introduce peaks somewhat higher than in original signal. This is the best way to keep the audio as original as possible, when SRC is on.
If Logic is doing SRC without this tiny peak level bump - I am afraid, they are using level reduction along with it.
I find Your suggestion to indicate that SRC takes place very appropriate and we will include it in v3.0 I think
VOX_Support_Team
#25
I think I found the reason:
Why we need SRC at all? because file and output have different sample rates, and for some reason the SR of file is not supported or not switched to in output device.
Logic probably is not doing this SRC, or it is doing it after Audio Units. This is fair/logical because after all it is designed to show the levels of Your original recording, not the monitoring output. The SRC, if any, could take place later between Logic and Core Audio, or, depending on Your setup, straight inside Your hardware.
On the other side, Vox tries not to delegate SRC to Core Audio as BASS has more options to control SRC quality and we use these to the max. You've noticed this when You switched sample rate manually in Audio Midi Setup - the SRC then takes place in Core Audio, because Vox didn't catch the change yet, once You re-start track - SRC goes back to Vox.
The difference here between Logic and Vox is that in later SRC takes place just prior to effects and Audio Units, because we want to process/monitor signal with AU's as close to output as possible. This is exactly not the case with Logic where we want to monitor the levels of file itself, not the output, without any conversion.
And since SRC had inescapable but tiny level changes this is what You see in Vox but don't see in Logic.
Knowing that might help You judging Your levels correctly in
Vox. Turns out You can model different SRC modes and see peaks of
Your material.
Hope this helps and we are here for any further comments.
Thank You for compliments,
Happy Holidays, btw!