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Author
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Topic: Difference between theatrical and Bluray releases
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Mike Blakesley
Film God
Posts: 12767
From: Forsyth, Montana
Registered: Jun 99
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posted 03-13-2015 03:34 PM
Oh yes, the subject has been discussed. There is one thread in particular where an "industry guy" pretty much got taken apart by the members here on that exact subject. I'm not sure what thread it is or I'd post a link to it -- maybe somebody else will link to it. It was a lively discussion. But the short answers to your questions are:
quote: Keith Barnes
Are Blurays re-mixed for release?
Yes.
quote: Keith Barnes
How different are they from the theatrical release?
I guess how much you would notice it depends on how familiar you are with the material, OR how picky you are, OR how good your home sound system is.
quote: Keith Barnes
Are levels changed in any way, or dynamic range compressed?
I think, yes and yes.
quote: Keith Barnes
Just what actually happens when a movie transits from a theatrical release to a Bluray release?
Each studio has a home video department who have to justify their jobs by pretending such tweaks are necessary when in reality, they really aren't (according to most of our opinions at least!) These people "adjust" the soundtrack for what they call a "near field mix" meaning the speakers are closer to your ears, so they need to make it sound different (or to use their term, "better.")
quote: Keith Barnes
And should we consumers be concerned?
If you're concern is that you want the exact same soundtrack you heard in the theatre, then yes. If you're just a casual fan and only care that you can still understand the movie and the story, then maybe not. To me a soundtrack tweak isn't nearly as awful as things like Steven Spielberg removing the guns from E.T. and similar stuff.
quote: Keith Barnes
Are Bluray releases 'dumbed down' for Joe Public listening and watching on a cheap, small TV with bad speakers, or are standards maintained across the board?
Definitely yes to the first part of your question, and probably not to the second part. I'm not sure there are "standards" for this kind of thing anyway.
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Mitchell Dvoskin
Phenomenal Film Handler
Posts: 1869
From: West Milford, NJ, USA
Registered: Jan 2001
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posted 03-13-2015 04:01 PM
What Mike said above.
Further, old analog Dolby Stereo (Dolby A and SR) were definitely modified for home video (Dolby ProLogic). Analog theater Dolby processors not only shift identical left/right sounds to the center, but they also raise the volume of the center channel. Dolby ProLogic does not raise the volume, although in some cases that was done at the source by the people mastering the disc. Dolby ProLogic does not encode for Dolby noise reduction.
For newer digital tracks, the question arises as to what is the "reference" theatrical soundtrack. Was it the Dolby Digital? The DTS? The SDDS? Each sound format had it's own mix, and in most cases, all 3 digital formats were on each film print (in different locations), so whatever processor the theatre was using would work with a single print. Then there is the issue of whether the 5.1 or the 7.1 mix is the reference, and which was the afterthought.
Then of course, you have films the were remixed thoughout their theatrical life. For example, Star Wars (1977) had at least 3 different sound mixes in it's original release, the final "reference" was the mono which was different from all the various stereo releases.
In addition, the acoustics of the room also effect the sound. Theatres that do sound right equalize their auditoriums with a spectrum analyzer, as do high end home theatre people. However, many theatres and consumers use the "it sound good to me" method.
As there really is no sound mixing "standard", it's up to the golden ears of whoever is doing the mixing, so I'm not sure that remixing for home video is really a problem as long as they do a good job.
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Keith Barnes
Film Handler
Posts: 3
From: United Kingdom
Registered: Oct 2013
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posted 03-14-2015 04:41 AM
Thanks guys. AIUI movies are mixed to Reference Level SPLs for theatrical release (85dB average, 105dB peak and 115dB peak LFE). When they remix for home release, do they maintain those levels or are they mixed/mastered a few dB lower overall, to try to compensate in some way for the smaller listening spaces of typical homes?
Also, can anyone shed light on what exactly a 'near field mix' is and how it differs from the theatrical release?
I should add that my interest is as someone who has a good Home Theater setup, with an acoustically treated and calibrated room, capable of playing cleanly at 'reference' levels.
In trying to reproduce the theatrical experience, but at home, it is important to understand what, if anything, has been done when the movie has been ported to Bluray, hence my interest.
Thanks again.
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Steve Guttag
We forgot the crackers Gromit!!!
Posts: 12814
From: Annapolis, MD
Registered: Dec 1999
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posted 03-14-2015 08:02 AM
quote: Mitchell Dvoskin
Analog theater Dolby processors not only shift identical left/right sounds to the center, but they also raise the volume of the center channel. Dolby ProLogic does not raise the volume, although in some cases that was done at the source by the people mastering the disc.
Incorrect on that one. "Pro Logic" refers to the 2:4 decoding process only. And in the cinema it was identical. To make that more plain and evident...check out a Dolby CAT150F (the last generation of the CAT150...there is one big chip on that board...an Analog Devices Pro Logic decoder. Come to think of it...the CAT 150E used a Sanyo Pro-Logic decoder.
The Pro-Logic decoder does not raise/lower Center per-say. It applies "steering." That is, it isn't just an L+R/L-R decoder for Center/Surrounds, it steers the sound into each channel such that if the signal should only be in the Center channel, it does attenuate the Left/Right to simulate a discrete mix. Thus you can pan a signal across the sound stage and it should pan right along with how it is mixed. How consumer and how cinema processors do it is identical.
Now, if you go back far enough, you'll find that before 1980 (when the CAT150 came out (and there were CAT150 - CAT150F so it evolved too) you WILL find something akin to what you were describing with the CAT110/CAT116 combination (Early CP50s and CP100s with SA3 and earlier). The CAT110 did do a process of raising/ducking L/R versus C. But that was at the beginning of Dolby Stereo (called Dolby System then). And the Dolby knock-offs like EPRAD's Starscope, couldn't even muster that...they just had you set the Center channel higher than Left/Right.
And for surrounds...Pro-Logic gets its origins from the CONSUMER Sansui QS "quad" decoder. In fact, the CAT116 used a genuine Sansui QS chip (as did the Eprad Starscope). Note, Eprad also evolved their decoder too.
A lingering difference in the Cinema versus Home mix are the surrounds. Cinema has a legacy to contend with . When "modern" surrounds came out in the 50s they were treated like any other channel and balanced to the same level. Reference tone/noise in the surround change should play as loud (as measured in the reference position) as any of the stage channels. However surrounds were mono (and stayed that way with the vast majority of movies until digital audio hit the cinemas in the early/mid '90s.
We needed to maintain a backwards compatibility such that the SAME movie would sound THE SAME (level wise) regardless of mono or stereo surrounds. This started with Dolby's format 43 which is the 70mm stereo surround format. So we are talking back in the late '70s...even before Pro Logic , as we know it, became the "standard" 35mm audio decoder (and it wasn't called that then). Maintaining the same level in that 70mm format was even more critical since it was only stereo above 500Hz...there stereo surrounds shared a common mono surround lower frequencies since "bass" is not as directional. However since the same track (track 6) is used for both formats, you are stuck with the same level.
Thus began setting up P and Q channels (As they were called on the CP100/CP200) at 82dBc each. This allowed the two to acoustically sum to 85dBc and maintain uniformity with mono surround mixes which would be for 85dBc with all surround speakers playing.
This has carried through to all film based formats. We always set to 82dBC per side...however consumer has always set each side surround to the same level as all other channels. So we have a 3dB difference. Even when Surround EX came out, a noted feature of the SA-TEN was the ability to calibrate levels such that regardless of mode, EX or 5.1 the surround SPL should be the same...even if you have it in the wrong mode! Not all Surround-EX emulators were as strict on this.
With DCinema, we can effectively shed this legacy because since day-1, DCinema has defined the sound to be 5.1 minimum based. Even a "1.0" mix is supposed to play in a 5.1 theatre properly (put it on track-3). Only the 2.0 people with Lt/Rt mixes (or mono placed on tracks 1 and 2) violate the design because cinemas are not supposed to be required to "decode" the standard track.
However, our bliss with 5.1 being the standard with 85dB/side wasn't long lived. With surround 7.1 we are now 82dBc/quadrant. so again, they should sum to 85dBc/side. Though, honestly, since Surround EX was there at the start of DCinema...the seemingly never used 6.1 DCinema format had us with 4 surround channels since day 1 as a possibility (even before 7.1). That said, the DCI spec remains that 85dBc per channel is the reference at -20dBFS (no reference to channel). We also have the advantage that when one plays a non 5.1 movie that it should be a Version File such that a 7.1 (or other "better" than 5.1) isn't playing in a 5.1 theatre in a 5.1 mode.
I do find it disturbing that setting the surround levels is not really well defined in most manuals and leaves a bit of ambiguity. The CP750 manual has always stated to set to 82dBC/quadrant. With the presumption that depending on how you configure your processor under the "General" tab as 5.1 or something better (now 7.1) it would "know" how to shift the levels as needed. USL and Datasat (AP20)is keeping with 82dBc for surrounds. Does it shift between 7.1 and 5.1? I guess you can adjust as needed on its output matrix. QSC, on their DCP line, doesn't specify any particular level that I'm aware. In my mind, with DCinema, we should have made the clean break and went with 85dBc/channel (except subwoofers) and let the people mixing the movie just set the level they want presuming that the right channel configuration is used at the theatre end. Why keep the 82dBc thing? And bringing this back full circle, consumer and pro would have the same reference levels. The DCI spec is pretty clear...all channels have the same reference level. The Cinema processor that has 7.1 capability should, by virtue of mode change (7.1 to 5.1) should "know" it has to drive each quadrant 3dB lower so that again -20dBFS of a 5.1 track is only 85dB when the two quadrants are summed (acoustically). However, as every cinema processor manual is written (that choses to write such things)...they read 82dB/side...so which is correct? And if you poll techs here, you are bound to get differing opinions on the interpretation. So it is no wonder that you will hear differences between the home and the cinema. In the home, people are going to set things AT LEAST to uniform using their whizbang box's built in generator. And likely to be surround heavy (opposite of cinema) because they love hearing the surrounds.
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