Porcupine Tree 5.1 remasters - Deadwing / In Absentia - getting nearer?

[edisonbaggins]

Could it be that the DTS HD was changed more than the LPCM?

Interesting question... Checking.

***They appear to be exactly the same. I just think the center phase correction helps quite a bit on one of my systems.***

 

[edisonbaggins]

In Absentia Deluxe Review
Did They Fix the 5.1 Mix?

 

[Albert Dagger]

In Absentia Deluxe Review
Did They Fix the 5.1 Mix?

Great to hear you are investigating the issue on the LFE channel. It would be good to solve this matter once and for all
I remember @Plan9 mentioning on the other forum that both centre and LFE channels are inverted. I'm looking into the In Absentia files as I type, and am not that confident the LFE is inverted. I can clearly see there's delay and the volume is low, but as you mentioned @edisonbaggins, it's hard to gauge whether that was a deliberate choice or a mistake. Like you, I'm happy with the blu-ray as is, but am curious and would like to get this right!

 

[edisonbaggins]

Great to hear you are investigating the issue on the LFE channel. It would be good to solve this matter once and for all
I remember @Plan9 mentioning on the other forum that both centre and LFE channels are inverted. I'm looking into the In Absentia files as I type, and am not that confident the LFE is inverted. I can clearly see there's delay and the volume is low, but as you mentioned @edisonbaggins, it's hard to gauge whether that was a deliberate choice or a mistake. Like you, I'm happy with the blu-ray as is, but am curious and would like to get this right!

With the LFE delay, depending on the tempo of certain songs, it can appear inverted, relative to the neighboring tracks. Maybe that contributed to Thomas's comment back when. I sincerely believe it's only delayed and low in amplitude, not inverted.

 

[knifeman]

In Absentia Deluxe Review
Did They Fix the 5.1 Mix?

Great review! I agree that the bonus tracks included definitely merit more than the usual "once and done' listen. I appreciate your detective work concerning these audio issues. This sounds pretty good to me and honestly, if I wasn't on this forum, I probably would never know about these problems. When you brought up Deadwing and FOABP, I thought uh-oh. Glad to see there's no phase issues with those two. Hopefully, Deadwing will follow, which I believe was the plan. For me, that's right there with In Absentia.

 

[The56Kid]

Thanks for the in depth In Absentia review and analysis, Mike. In Absentia is one of my favorite recordings of the last 20 years and I’m more glad than ever to have ordered the deluxe edition from Burning Shed!

 

[Plan9]

With the LFE delay, depending on the tempo of certain songs, it can appear inverted, relative to the neighboring tracks. Maybe that contributed to Thomas's comment back when. I sincerely believe it's only delayed and low in amplitude, not inverted.

Yes you're right the LFE wasn't inverted, I was going by my faulty memory of the fixes back then.

 

[Plan9]

About the 7.6dB boost for the LFE, IIRC (that was 3 years ago) I arrived at this conclusion by analyzing the original mastered 5.1 channels; that is the amount the LFE needs to be boosted to arrive at the maximum admissible level for a LFE track, and compared with the levels of the other channels. It was also consistent with the filtering needed for a lossy DTS track at the time. Not sure if I'm being clear, but it was purely a deduction as I didn't have the un-mastered 5.1 mix to check against.

As for the 10ms delay, I remember noticing it at the time, but after checking I didn't think it made a difference either way.
I passed on the information to Steven.

 

[edisonbaggins]

About the 7.6dB boost for the LFE, IIRC (that was 3 years ago) I arrived at this conclusion by analyzing the original mastered 5.1 channels; that is the amount the LFE need to be boosted to arrive at the maximum admissible level for a LFE track, and compared with the levels of the other channels. It was also consistent with the filtering needed for a lossy DTS track at the time. Not sure if I'm being clear, but it was purely a deduction as I didn't have the un-mastered 5.1 mix to check against.

As for the 10ms delay, I remember noticing it at the time, but after checking I didn't think it made a difference either way.
I passed on the information to Steven.

Looking quickly at the original IA 5.1 release, at Deadwing DVD-A and FoaBP DVD-A, it appears that IA and FoaBP are both delayed by around 10ms, but Deadwing is not.
Can you think of some kind of tool or process that might introduce such a delay? It's good that it doesn't seem to affect sound much (maybe it does on systems that rely on bass-management most heavily though?).
I don't want to get paranoid and start checking all LFE's for how well they're synced. This just became interesting suddenly (to me, at least) because of IA Deluxe.

 

[The56Kid]

Looking quickly at the original IA 5.1 release, at Deadwing DVD-A and FoaBP DVD-A, it appears that IA and FoaBP are both delayed by around 10ms, but Deadwing is not.
Can you think of some kind of tool or process that might introduce such a delay? It's good that it doesn't seem to affect sound much (maybe it does on systems that rely on bass-management most heavily though?).
I don't want to get paranoid and start checking all LFE's for how well they're synced. This just became interesting suddenly (to me, at least) because of IA Deluxe.

My system incorporates bass management and all 3 releases sound wonderful to my ear. Would have never guessed at the delay as Colin Edwin’s low end typically sounds massive.

 

[DuncanS]

Is the LFE full frequency or band limited? As a 10ms group delay for a Low Pass Filter which is 3dB down at 100Hz would not be excessive, its one complete cycle of 100Hz.

 

[Plan9]

Is the LFE full frequency or band limited? As a 10ms group delay for a Low Pass Filter which is 3dB down at 100Hz would not be excessive, its one complete cycle of 100Hz.

IIRC it is indeed Low Pass filtered

 

[DuncanS]

IIRC it is indeed Low Pass filtered

That might be why there is a delay, it is inherent in any filter digital or analogue. So the delay will be larger the higher the filter order, and also therefore the quicker the filter rolls off. Of course it could just be a 'quirk' introduced in the file outputting by the source program.

 

[edisonbaggins]

That might be why there is a delay, it is inherent in any filter digital or analogue. So the delay will be larger the higher the filter order, and also therefore the quicker the filter rolls off. Of course it could just be a 'quirk' introduced in the file outputting by the source program.

Any idea why a filter would do that?

 

[MarkN]

I still have not received my replacement Blu-ray from Snapper Music, and my recent emails to them seem to be going unanswered. I got an acknowledgment from them back on March 9th that they would send me a replacement when they were available. Not too pleased at this point, and as a result will be highly unlikely to buy the Deadwing set when and if it is released.

 

[bluelightning]

[

Any idea why a filter would do that?

This is just the basics of how filters operate. Typical digital filters utilize delay elements (called time taps) to create time delayed versions of the signal. These are then added together in various combinations to create desired frequency responses. There are of various types of filters, however they all introduce delay components in one form or another.

 

[DuncanS]

Any idea why a filter would do that?

Difficult to easily explain! Mathematics and graphs are really needed to show it.
The best explanation I can give is that the filtering 'action' introduces a phase shift which is different for different frequencies, a phase shift in a filter is a time delay. Group delay is related to the filters transient response. So if you put a step pulse into a Low pass Filter the output will not be a step but a 'ramp', this due to the higher frequencies being delayed by more than the lower ones, plus higher frequencies will also be attenuated as it is a low pass filter. So a delay is inherent in any type of filter.
The lazy explanation is its magic

 

[Beefalo]

About the 7.6dB boost for the LFE, IIRC (that was 3 years ago) I arrived at this conclusion by analyzing the original mastered 5.1 channels; that is the amount the LFE needs to be boosted to arrive at the maximum admissible level for a LFE track, and compared with the levels of the other channels. It was also consistent with the filtering needed for a lossy DTS track at the time. Not sure if I'm being clear, but it was purely a deduction as I didn't have the un-mastered 5.1 mix to check against.

As for the 10ms delay, I remember noticing it at the time, but after checking I didn't think it made a difference either way.
I passed on the information to Steven.

All I know is that raising the LFE like you describe really works for my ears.
I found the treble on I.A. to be a little hot.
Raising the the LFE really balanced out the sound for me. Thanks

 

[edisonbaggins]

I guess it's possible that the only two fixes truly needed, then, are to 1) invert the center and 2) raise the LFE.

If a 10ms delay is the result of a filtering tool, then it's not necessarily a "problem" or "mistake".

Now, shifting it back 10ms certainly doesn't harm the sound, to my ears. It's maybe just unnecessary.

 

[Lord British]

Difficult to easily explain! Mathematics and graphs are really needed to show it.
The best explanation I can give is that the filtering 'action' introduces a phase shift which is different for different frequencies, a phase shift in a filter is a time delay. Group delay is related to the filters transient response. So if you put a step pulse into a Low pass Filter the output will not be a step but a 'ramp', this due to the higher frequencies being delayed by more than the lower ones, plus higher frequencies will also be attenuated as it is a low pass filter. So a delay is inherent in any type of filter.
The lazy explanation is its magic

Man, there sure are some subjects on this forum that go right over my fu**ing head. I'm glad someone out there understands the nuts and bolts of this stuff, it just isn't me.