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25 Hz filter on BD DTS tracks? - Page 31

post #901 of 928
6/11/10 at 8:47pm
Quote:
Originally Posted by craig john View Post

Now there's a switch... I suggested he turn *off* Bass Management, and you suggested he use it!

well he already shot down large so i figured i'd go for the next best thing

a lot of this is room dependent

there's no "one size fits all" rules in this game

i could move my system into the next room and "might" hate running large speakers

as you found out, just adding a 3rd sub made you switch to a different crossover point. it's all trial and error
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post #902 of 928
6/12/10 at 9:39am
I wonder if the Academy Awards "viewing room" has been updated since the last major renovation (1990-91)?


Academy Awards movie "viewing room" renovation
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post #903 of 928
6/12/10 at 1:35pm
Man, this thread digressed. Not really willing to read 16 pages. What was the result aside from the several examples sited? Does BD, in general, truncate at 25 Hz LFE?

-T
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post #904 of 928
6/12/10 at 1:43pm
Quote:
Originally Posted by T-Bone View Post

Man, this thread digressed. Not really willing to read 16 pages. What was the result aside from the several examples sited? Does BD, in general, truncate at 25 Hz LFE?

Nope. Master and Commander seemed to be the only real case. Some kind of authoring error or fluke. Avatar was remixed for home audio and unfortunately, for whatever reason, the mixers decided to tone down the low end (for certain scenes). Honestly, I think this thread should be closed. All it does now is just spread misinformation and misconceptions from the sensationalist title.
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post #905 of 928
6/12/10 at 3:07pm
Quote:
Originally Posted by J_Palmer_Cass View Post

I wonder if the Academy Awards "viewing room" has been updated since the last major renovation (1990-91)?

Yes, the entire B-chain thru to the speakers is changed. I'll be getting more details next week if you want them.
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post #906 of 928
6/12/10 at 3:29pm
Quote:
Originally Posted by Roger Dressler View Post

Yes, the entire B-chain thru to the speakers is changed. I'll be getting more details next week if you want them.



That would be very nice to know.

Kind of strange that most of the DVDs that I have looked at seem to have no infra content on the LFE channel, yet when there is infra there is plenty of infra on various combinations of main channels.

No consistent placement of infra on each DVD. Sometimes R & L, sometimes C alone, sometimes L, C, and R and sometimes no infra.

Just trying to figure out what the Academy system does with the routing of infra that is on the main channels. Do they bass redirect now, have more competent mains, or do they just let the main roll off on their own? The LFE channel itself does not seem to include infra very often which seems to be counter intuitive.

I know that the theaters used to call the .1 channel the subwoofer channel, but maybe that is not true these days. Maybe it is LFE plus RB.

Low end extension of the mains and subwoofers would be nice to know also.
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post #907 of 928
6/12/10 at 5:01pm
Quote:
Originally Posted by J_Palmer_Cass View Post

I wonder if the Academy Awards "viewing room" has been updated since the last major renovation (1990-91)?

Quote:
Originally Posted by J_Palmer_Cass View Post

Just trying to figure out what the Academy system does with the routing of infra that is on the main channels. Do they bass redirect now, have more competent mains, or do they just let the main roll off on their own?

Low end extension of the mains and subwoofers would be nice to know also.

Do you really think that the very low-end content is that important a determinant of the Academy's awards' decisions? This would seem counter to your general mindset regarding the relative unimportance of the very low-end stuff. I suspect it is a relatively minor determinant of the results, if at all. Many soundtracks that win the awards probably DO have nice low-end content but that is certainly not solely why they win the awards.

Also, do you know how the nomination and judging process for the sound awards works? I do not know for those particular awards, but my sister works in the business as a set dresser and she has friends and associates who are members of The Academy that participate in the nomination process for the Art Department related awards. They are sent DVDs of movies to screen in their own homes, at their leisure, on whatever playback equipment they desire. Once the nominations are determined by mail-in ballot there is another round of voting for the winners. I do not know if this how the sound awards nomination and final judging process might work or not. The Academy has hundreds of members.
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post #908 of 928
6/12/10 at 5:14pm
we need a "subwoofer general chat and theory" thread where people can talk about whatever they want

noobs can come in and ask their questions instead of starting 500 "which sub should i get" threads a week

subwoofer set-up, bass management theory and whatever else can be talked about till the cows come home

nothing is "off topic". if you want to just post the latest movie you saw or song you heard with great bass

you can even talk about the weather if you want

standard avs rules would apply of course

start one up sivadselim
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post #909 of 928
6/12/10 at 7:54pm
Some excerpts...

Quote:


DOLBY ENCODING GUIDELINES:

5.1.2 The LFE Channel
Since the reproduction of the LFE channel can be considered optional, essential low frequency information should not be mixed exclusively to the LFE channel. In fact, in most downmixing situations, the LFE is completely disregarded. Conversely, in some rare cases, there may be a consumer playback system with small speakers, incapable of deep bass reproduction, yet lacking the bass management to direct the main channel bass to the subwoofer. In such cases, the LFE channel is all the bass that will be heard.

Also notice that the LFE channel may be disregarded in some circumstances, which should be kept in mind when deciding what content to include in the LFE channel during mixing.

Bass management
____________________________________________________________ ____
Note: Always check your mix using a Bass managed system
____________________________________________________________ ____

Some music engineers feel that there is no need for the LFE channel at all. Because many of the popular consumer 5.1 speaker packages direct all of the
bass from the main channels to the sub, however, combining it with any LFE information that may be present, it is important to at least check the effect bass management has on a mix while still in the studio. For example, in one known case, the combined bass from the main speakers was out of phase with the LFE channel, virtually eliminating the low end of the program when played back through a consumer, bass managed system.
____________________________________________________________ ____
Even though bass management is not required when monitoring in a studio with full range speakers and a subwoofer, it is useful for checking how redirected low frequencies from any of the main channels may interact with the LFE channel information. Remember that the consumer is likely to use some form of bass management, so proper bass management is necessary to emulate a consumer home theater system.
____________________________________________________________ ____
Again, the goal in production and home playback is to hear all the bass accurately, regardless of which speaker reproduces it. When using full range speakers with good bass response, there is theoretically no need for bass management, even when using a sub for monitoring the LFE channel. However, the track should still be listened to at some point with bass management engaged, to emulate what the consumer will hear.

I'm only attempting to address the incorrect notion that because cinemas don't use BM, studios that encode for DVD and BR releases don't use BM. The Dolby guidelines also address the reason for finding significant low end in the main channels, instead of exclusively in the LFE channel.

Bosso
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post #910 of 928
6/13/10 at 10:09pm
I found something interesting while reading up on some old DIY build threads. Also, I am not trying to stir the pot or single out Bosso (link to a quote from Bosso) but I thought it would relate to this thread.

http://www.avsforum.com/avs-vb/showt...4#post15622834

Quote:


One last point: If you've got the dough and real estate to spare, don't shrug off the sub-20Hz content I've shown in the reference waterfall plots as unintended artifacts—say, scraps of subway rumble or HVAC noise—that somehow slipped through the filters during the mixing process. The content is program-related and meant to be there. So, okay, as a hardware matter, how did the engineers at Todd-AO who snagged an Academy Award for Best Sound for Black Hawk Down monitor all that gut-twisting infrasonic content—all those rumblings I've mentioned that lie just beyond the reach of even refrigerator-sized subs? They used big Bag End subwoofers—22 of 'em.

Somebody is listening to the <20hz range.

Our old friend JBL4645 even did a plot from BHD just a few posts down from this link showing infra content in the LFE channel.
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post #911 of 928
6/14/10 at 6:27am
Quote:
Originally Posted by Scott Simonian View Post

I found something interesting while reading up on some old DIY build threads. Also, I am not trying to stir the pot or single out Bosso (link to a quote from Bosso) but I thought it would relate to this thread.

http://www.avsforum.com/avs-vb/showt...4#post15622834



Somebody is listening to the <20hz range.

Our old friend JBL4645 even did a plot from BHD just a few posts down from this link showing infra content in the LFE channel.



Tee hee. That was already quoted by Bosso earlier in this thread.

The 5-10 Hz content located on the LFE channel of Black Hawk Down is simply a bi-product of the sound effect. The 5 to 8 Hz content is not meant to be heard yet it can be filtered out of the effect without gutting the effect.

The ballpark sound effect is a primary tone in the 18 to 20 Hz area. This prime frequency is FM modulated by a second tone in the 25 Hz area that results in a lot of harmonics on the spectrogram. The infra frequency varies from 5 to 10 Hz depending on the scene in question.

I made and listened to a sample of a manufactured FM modulated signal on my PC speakers (maybe 45 Hz low end if I am lucky?). Sounds similar to Black Hawk Down helicopter low frequencies. Now when I filtered out only that 7 Hz FM modulated bi-product from the sound feeding the speakers, the other higher harmonics still are shown on the spectrogram.

Just as a note, the infra content of the BHD helicopters varies between 5Hz and 10 Hz depending on the scene. Filter that out, and there is not much content below 18 Hz.
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post #912 of 928
6/14/10 at 6:41am
If I'm understanding you correctly, you are saying that those of us with good, low tuned ported subs or for that matter, sealed subs that have high-pass filters at say 15hz or so (such as Rythmiks) cannot play back the primary tone at 18-20hz? Why is that?

Also, how do you know that the signals from 5-10 hz are unintentional?
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post #913 of 928
6/14/10 at 6:58am
Quote:
Originally Posted by mojomike View Post

If I'm understanding you correctly, you are saying that those of us with good, low tuned ported subs or for that matter, sealed subs that have high-pass filters at say 15hz or so (such as Rythmiks) cannot play back the primary tone at 18-20hz? Why is that?

Also, how do you know that the signals from 5-10 hz are unintentional?


You have it arse backwards. You can always hear the primary tone regardless of whether it is modulated or not modulated.

A modulated tone (be it AM or FM) will just produce a ton of harmonics which can be heard. The FM modulated 18 to 20 Hz primary tone sounds nothing like a pure 20 Hz tone. I had to LP the sample at 120 Hz to keep the harmonics within the LFE band. One subharmonic frequency is generated in the infra band while a ton of harmonics are generated above the primary tone.

I assume that the Black Hawk Down helicopter sounds are not manufactured sounds, but who knows. They helicopter sounds are modulated sound effects.

Anyhow, there is no infra in the gunshots and various explosions for that movie.
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post #914 of 928
6/14/10 at 7:36am
You said:

Quote:
Originally Posted by J_Palmer_Cass View Post


The 5-10 Hz content located on the LFE channel of Black Hawk Down is simply a bi-product of the sound effect. The 5 to 8 Hz content is not meant to be heard yet it can not be filtered out of the effect without gutting the effect.

I said:
Quote:
Originally Posted by mojomike View Post

If I'm understanding you correctly, you are saying that those of us with good, low tuned ported subs or for that matter, sealed subs that have high-pass filters at say 15hz or so (such as Rythmiks) cannot play back the primary tone at 18-20hz? Why is that?

Quote:
Originally Posted by J_Palmer_Cass View Post

You have it arse backwards. You can always hear the primary tone regardless of whether it is modulated or not modulated.

What part do I have backwards? You are saying that filtering out the 5-8hz byproduct guts the effect, but then you are saying that you can always hear the primary tone. Which one is it? You are contradicting yourself.
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post #915 of 928
6/14/10 at 9:56am
Quote:
Originally Posted by mojomike View Post

You said:



I said:




What part do I have backwards? You are saying that filtering out the 5-8hz byproduct guts the effect, but then you are saying that you can always hear the primary tone. Which one is it? You are contradicting yourself.


Corrected typo in original posting. Removed the word "not". Anyhow, 18 to 20 Hz is the primary tone for BHD. 5 to 10 Hz content is a FM modulation artifact.

The movie Transformers has a helicopter signature similar to the BHD helicopter, but no low infra content (5 to 10 Hz) can be seen on the transformers waterfall. Both helicopters sound very similar when played back at my normal listeninge level, which is about 6 dB below reference level.

If you filter the BHD waterfall to represent what you can hear, the 5-10 Hz infra probably is not noticable even if you are flat to DC.
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post #916 of 928
6/14/10 at 4:19pm
Quote:
Originally Posted by Sujay View Post

Honestly, I think this thread should be closed. All it does now is just spread misinformation and misconceptions from the sensationalist title.

Blame JPC.
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post #917 of 928
6/14/10 at 8:53pm
Quote:
Originally Posted by AuralXTC View Post

Blame JPC.


Hey rookie (161 postings), that one belongs to Bosso. After all, who is the one person who started the infra lovers panic about the so called 25Hz filter being on BD DTD tracks.

I simply evaluate what is recorded on the original DVD. Even the Master and Commander Bluray is not filtered any different than the original DVD version.
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post #918 of 928
6/14/10 at 9:01pm
Quote:
Originally Posted by bossobass View Post

Some excerpts...



I'm only attempting to address the incorrect notion that because cinemas don't use BM, studios that encode for DVD and BR releases don't use BM. The Dolby guidelines also address the reason for finding significant low end in the main channels, instead of exclusively in the LFE channel.

Bosso



That is your spin on what was written. Infra is never mentioned. Audio that can be heard in mentioned.

The Grammy Paper is at times a more detailed and a somewhat better read than that Dolby encoding guideline. The Dolby guidelines does give much more encoder detail that is not seen in the Grammy recommendations.


Quoted from Grammy recommendations.


"2.2 Professional Mixing Environment

A professional mixing environment is, by definition, an acoustically tuned room that optimally provides flat frequency response across the full bandwidth. Of course, no room is perfect, and compromises can and often are made, but the goal is to provide the mixing engineer with an accurate picture of the sound that has been recorded and to allow a balanced blend between envelopment and localization. To that end, the monitoring system must deliver the full range of audible frequencies, and it must be positioned and calibrated correctly. (See sections 3.3 and 3.6)

All main speakers should be identical, of the same brand and model. Only full range direct radiator speakers should be used; satellite and dipole speakers have no place in the professional mixing environment (see section 3-2). Mid-field monitoring is usually preferred for surround mixing. (Unlike nearfield monitors, mid-field monitors are designed to be used free-standing and not placed on top of a console meter bridge.) In the interest of uniform frequency response, all main speakers should be placed on speaker stands; the front speakers should not be placed on top of the console meter bridge. The use of movable speaker stands can be helpful if the rear speakers are to be shifted or angled differently from project to project because of genre-specific considerations (see section 3.3.1).

At least one subwoofer must be used, ideally positioned along a boundary wall in front of the mix position (see section 3.3.2). Bass management in the professional mixing environment is optional and at the discretion of the engineer; however, depending upon the specific monitoring system being used and the room design, it may prove to be unsatisfactory and yield inaccurate results. We do, however, recommend that there be a separate bass-managed consumer system available (optimally installed in a room that emulates the home theater environment — see section 2.3) to check mixes on."
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post #919 of 928
6/21/10 at 8:51am
Originally this thread started out with posts about mainly Master and Commander and the possible differences in the dts core and BD lossless track. I am about to buy this movie and am trying to decide if I should get the dvd or the BD for the best bass experience. Have we reached a consensus yet about this movie?

Somewhere I had read that there have been at least 2 different dvd versions that existed, one being better than the other. The dvd's I find on amazon seem to have both a 5.1 DD and a 5.1 DTS for english, would this be the one that has the infrasonics still present?
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post #920 of 928
6/21/10 at 12:45pm
There are several different blurays as well. Did anyone ever figure out which batch of blurays seem to have this filter?

On a side note, I rewatched LOTR:ROTK and it seems for some unknown reason my system's calibration was off the first time. The bluray has the same bass but the audio and video overall are much better. The bluray is better. Sorry about the confusion if any.
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post #921 of 928
6/21/10 at 2:11pm
Cool. And with that we can move on from this, "oh, no! Are my BD's gonna be filtered <25hz." blah blah blah.

It was just Master and Commander and not by much, really.
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post #922 of 928
6/21/10 at 8:20pm
For what it's worth.....

LFE comparisons on two movies.

Apollo 13......Blu ray better than DVD....check out blastoff scene.

The Day After Tomorrow......Blu ray better than DVD.....the whole movie.
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post #923 of 928
6/22/10 at 6:15am
Quote:
Originally Posted by T-Bone View Post

Man, this thread digressed. Not really willing to read 16 pages. What was the result aside from the several examples sited? Does BD, in general, truncate at 25 Hz LFE?

-T

Depends on who you ask...this isn't even a discussion now it's two dudes arguing over toys!This discussion should've been closed IMHO!
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post #924 of 928
6/23/10 at 10:44pm
Thread Starter 
As far as I am concerned the question has been answered. Only one film seems to have a bass issue between DVD and BD. I have updated the original post to state that only M&C seems to have this issue. Thank you to those that took the time to look into the various films, measure, post, etc.
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post #925 of 928
6/24/10 at 5:05pm
While it's basically been figured out that only M&C suffers from this "issue" and it could be argued Avatar does as well, I think we should keep the thread open in case anyone happens to come across any other strange pressings of Blu-Rays like M&C.

That way anyone who thinks they've found another has somewhere to post their thoughts instead of starting a new thread. No point in closing it, really.
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post #926 of 928
6/25/10 at 7:08am
Would a fair conclusion to the thread be to list dvd/bd versions of Master and Commander that appear to have a 25hz hpf and those that don't? It's not at simple as "the DVD is not HPF'd and the BD is..." There have been at least 2 dvd versions and it seems that only one of them is wrought with infrasonics, but which one? Someone else at one point suggested that there also might be more than one BD version as well, each with different audio spec sheets. Sorting thru the facts of all the various versions would put a nice cap on this thread and answer the question the title poses.

I am still looking for the answer to this because I am about to buy this movie and want the best bass experience.
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post #927 of 928
6/25/10 at 7:30am
I think you will be pretty safe with the standard DVD that features DTS sound.
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post #928 of 928
7/7/10 at 12:19pm
Quote:
Originally Posted by Sideofpotatos View Post

Would a fair conclusion to the thread be to list dvd/bd versions of Master and Commander that appear to have a 25hz hpf and those that don't? It's not at simple as "the DVD is not HPF'd and the BD is..." There have been at least 2 dvd versions and it seems that only one of them is wrought with infrasonics, but which one? Someone else at one point suggested that there also might be more than one BD version as well, each with different audio spec sheets. Sorting thru the facts of all the various versions would put a nice cap on this thread and answer the question the title poses.

I am still looking for the answer to this because I am about to buy this movie and want the best bass experience.

Me too! I rented the movie from Blockbuster on BD and it was the BEST bass experience I've ever had anywhere. I wonder if the studio heads got the message and updated? I'd like to know as well because I'd like to get my money's worth.
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