Old 09-17-2012, 06:23 PM   #41
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So maybe I am not understanding what these modes actually do..... If I have the playback mode set to extreme, and am doing a playback or real-time render, would this mode even make a difference if all of the audio is at the same sample-rate (no conversion going on)?
No, if all the audio is the same sample rate as what the soundcard is set to then there is no re-sampling going on. These settings are only for when there is a mismatch between the sample rate of the audio file and the sample rate of the soundcard.

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Well...I'm not entirely sure now that you bring it up. Isn't there resampling going on to go from the 64bit mix engine to whatever fixed point format it outputs in (whether via speakers or DAC)? I always assumed that was what those modes were for.
As I eluded to above, resampling only applies to a change or mismatch in sample rate, dither applies to a (downwards) mismatch in bit depth.
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Old 09-17-2012, 06:29 PM   #42
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No, if all the audio is the same sample rate as what the soundcard is set to then there is no re-sampling going on. These settings are only for when there is a mismatch between the sample rate of the audio file and the sample rate of the soundcard.

As I eluded to above, resampling only applies to a change or mismatch in sample rate, dither applies to a (downwards) mismatch in bit depth.
Dither is the random noise that's added to accommodate bit depth changes. But I think you're right, resampling doesn't apply to bit depth truncation. So I'm not sure why there would be a difference, then, the test I performed did not include any resampling that I can recall (I'll have to retest to be absolutely sure when I get back but that wouldn't be something I would have done in a single variable comparison test).
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Old 09-17-2012, 06:46 PM   #43
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So we still have no idea why there would be a difference in the glue and render qualities...?
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Old 09-17-2012, 07:33 PM   #44
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i just discoverd something worth mentioning:
glue and "apply fx.." use playback resample settings.
render stems , render dialog and freeze use the render resample settings.
If this is true then it explains everything...in the original post Europanaut was resampling from 88.2 to 48khz. In the process he noticed if he glued or rendered he would get slightly different results. This can be explained by having perhaps a playback resampling mode that was not quite close enough to the render resampling mode for them or the original to null.

As far as the bit depth change creating a non-nulling file...if you go from a higher bit depth to a lower one you are essentially chopping out very low level audio (truncating or dithering it away if you will) so since something that was there in the original is no longer there in the new, lower bit depth copy you will not get a perfect null. The difference should be exceedingly quiet but it will be there.
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Old 09-17-2012, 07:37 PM   #45
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If this is true then it explains everything...in the original post Europanaut was resampling from 88.2 to 48khz. In the process he noticed if he glued or rendered he would get slightly different results. This can be explained by having perhaps a playback resampling mode that was not quite close enough to the render resampling mode for them or the original to null.

As far as the bit depth change creating a non-nulling file...if you go from a higher bit depth to a lower one you are essentially chopping out very low level audio (truncating or dithering it away if you will) so since something that was there in the original is no longer there in the new, lower bit depth copy you will not get a perfect null. The difference should be exceedingly quiet but it will be there.
You're right plush2, that would explain it.
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Old 09-17-2012, 08:07 PM   #46
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If this is true then it explains everything...in the original post Europanaut was resampling from 88.2 to 48khz. In the process he noticed if he glued or rendered he would get slightly different results. This can be explained by having perhaps a playback resampling mode that was not quite close enough to the render resampling mode for them or the original to null.

As far as the bit depth change creating a non-nulling file...if you go from a higher bit depth to a lower one you are essentially chopping out very low level audio (truncating or dithering it away if you will) so since something that was there in the original is no longer there in the new, lower bit depth copy you will not get a perfect null. The difference should be exceedingly quiet but it will be there.
Ya you betcha! The Canuck for the goal!! (Meant as a friendly jab, not malicious!!)
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Old 09-17-2012, 08:23 PM   #47
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Ya you betcha! The Canuck for the goal!! (Meant as a friendly jab, not malicious!!)
No malice taken. Perhaps in keeping with my nation's character it is I who should be apologizing to you. hehe
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Old 09-17-2012, 08:28 PM   #48
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No malice taken. Perhaps in keeping with my nation's character it is I who should be apologizing to you. hehe
We'll just call it even.
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Old 09-17-2012, 10:53 PM   #49
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I am also wondering how one would know which mode (either render or playback) is being used while gluing.
just an A /B test. but this time not the null-test.
i did compare the files byte by byte with an external editor. they were identical with equal resample quality-settings and they weren´t with different settings.
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Old 09-17-2012, 11:28 PM   #50
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just an A /B test. but this time not the null-test.
i did compare the files byte by byte with an external editor. they were identical with equal resample quality-settings and they weren´t with different settings.
Thanks for doing the leg-work on that one. Nicely done.
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Old 09-18-2012, 10:11 AM   #51
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Hmmmmm.....I'm starting to wonder whether my issues are system-specific.

I've matched the playback and render settings in the project settings window. When I glue, the 88.2 original and 48k glued tracks still don't null.

Render still nulls fine.

Then I tried glueing a file at "good", then at "best". Those two tracks DID null to one another.

Do I have to reopen the project after making the settings changes or something?

I just checked the source window of all three new files. Both glued files (playback settings at "good" and "best") come in at 14,244,296 samples. The rendered file, which does null, came in a 14,982,476.

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Old 09-18-2012, 11:24 AM   #52
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Is there any other pitch shifting or time-stretching going on with the audio to be rendered/glued? Something like that might explain the difference as well.
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Old 09-18-2012, 01:01 PM   #53
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Is there any other pitch shifting or time-stretching going on with the audio to be rendered/glued? Something like that might explain the difference as well.
Nope. The only mods are due to comping from various performances. No effects at all. No pitch shift or time stretching.
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Old 09-18-2012, 01:10 PM   #54
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In order for me to follow this conversation, can someone explain wht "null" means?

I mean, I know it means zero, but am trying to figure out what the zero means in the context of recording.
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Old 09-18-2012, 02:07 PM   #55
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In order for me to follow this conversation, can someone explain wht "null" means?

I mean, I know it means zero, but am trying to figure out what the zero means in the context of recording.
Null is referring to a quick and common test in digital audio based on the principal that the same audio data when played concurrently with a phase reversed copy of itself (ie. when the one files wavedraw is going up past the center line the other is doing the exact opposite by going down) will cancel out to no signal. It's a really simple and quick way of knowing whether two files are identical or nearly identical. Differences show up right away as audible or meter readable signal.
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Old 09-19-2012, 01:30 PM   #56
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I've matched the playback and render settings in the project settings window. When I glue, the 88.2 original and 48k glued tracks still don't null.

Render still nulls fine.
In my tests so far, nothing that I've rendered or glued to a lower sample rate nulls with the 88.2 track. I also found that two files (one rendered and one glued, in the same sample rate) did null, but only when the project sample rate matched those files. Ex: A render and a glue of the same file at 44.1K nulled when my project sample rate was set to 44.1K, but those same files would not null when the project sample rate was set to 48K. The same applied for 48K files when my project sample rate was set to 44.1K
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