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The Low Frequency Content Thread (films, games, music, etc)


maxmercy
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Speaking of the 20-30 hz impact, do you think an alternative rating system (still measured and scientifc) could be used to generate another list of "Best impact bass movies" or something along those lines.  A rating system that ignores extension below maybe 12 hz, and focuses a bit more on execution and level?  I'm not sure what to do for rating dynamics, I find that they aren't much of a factor if a movie's bass sounds good to me or not.  Maybe even reverse the "star" rating of dynamics, as I actually prefer low dynamic bass.

 

Waaaay too much 'left to interpretation' in the phrase 'Best Impact movies'.  Sooo much of what people perceive as 'impact' has more to do with your particular room, furniture and body resonances to simply say one particular freq range is 'impact'.  The way we do it, you can look at a PvA graph, look at the stats, and by experience (and knowing your room), you can tell pretty quickly whether or not a film will rock your world.  If you go back and read through the thread, you will read about all of us discussing very similar things, with trial and error until the current system was put into place.

 

   

 

I think what's needed is to weight the response using equal loudness contours (ELCs) to assess how subjectively loud it sounds. Dynamics could be determined using a ratio of the max ELC-weighted response over short-times vs. ELC-weighted long-time response. There's still the question of how long of a window to use for the short-time average. It might be helpful to use a few window sizes with different filters (i.e., low-pass with lower cut-off for longer window) to give fair weighting to the ULF.

 

You are more than welcome to re-measure over 100 films in your spare time with different FFT settings.  But the current system was not decided upon on a whim.  One of the things that always bothered me about the FFT and PvA graphs is that neither tells the whole story.  But adding in the overall peak, RMS peak, and Dynamics numbers helps round out what the PvA cannot tell you.  Nearly every film I have measured has a full-range PvA that drops at 3dB/octave or more above 100Hz with few exceptions.  That's why we use full-range data for Peak, RMS Peak and Dynamics numbers, as they are already hevily bass-weighted.

 

The tricky part is knowing the proper reference volume for each track. In my mind, that's a more fundamental issue since I'm fairly certain many highly-rated (and some not so highly-rated) bass Blu-rays were mixed with monitoring at lower levels, so that theatrical reference is too loud. For example, Star Trek sounds to me like it was mixed at or very near theatrical reference; whereas, STID sounds like it got mixed closer to -10 (and clipped to death in the process of giving up 10 dB headroom). If this difference in reference volumes were taken into account, STID would end up with an even lower rating!

 

This is very tricky, ATSC has a system in place for determining reference level depending on the size of the room and the amount of acoustic treatment.  Tomlinson Holman posted on AVS that in smaller mix rooms, Reference level is 81dB as it 'matches' with 85dB reference in a larger room.  This is something we are likely never to know.  If an action film has >30dB dynamics, and 4 or 5 Star Level, then I am reasonably sure that it is the theatrical mix.  

 

Sad to say, we may never know the correct reference levels for a variety of Blu-ray releases. The best we could try to do is guess by doing some kind of analysis against the dialog. From what I've read out there, both -3 and -6 are common monitor level choices for DVD and Blu-ray mixes. From what I hear (subjective interpretation) listening to media some other recent releases were likely mixed at or near -10 dB. I think Looper may also have been mixed closer to -10. This is a big deal, because if Looper were played back at -10, the deep bass wouldn't be anywhere near as loud subjectively, and it sounds more like a movie with 3 stars extension than one with 5.

 

I'd sure appreciate it if the studio would print the reference level somewhere on the box or at least populate the appropriate metadata like Dialnorm properly. Anyone remember the VHS days when they added the disclaimer at the start of the film: "this film has been modified to fit your TV screen"? I think they should be obligated to add a similar notice whenever they do a separate mix for Blu-ray. It's rather disingenuous in my view to claim that the a lossless "DTS-HD" or "Dolby TrueHD" track is "bit-by-bit" identical with the theatrical master as some of the early Blu-ray advertising implied. Really, I wish they'd just ship the theatrical mixes in the lossless formats and do the "made for the home" mixes with reduced dynamics in lossy Dolby Digital or DTS. My experience has been that the differences between a good lossy codec and the lossless original are most apparent with tracks having very high dynamic headroom.

 

Agreed.  I wish we could get the theatrical mix, as well as the kid's table mix with the theatrical mix being lossless.

 

Also, I'd hazard a guess that it is in the process of creating the "made for the home" mixes where a lot of clipping as well as high-pass/high-shelf filtering tends to happen. In many instances the filtering we frequently observe may have been added in that mix process to reduce or prevent clipping.

 

Clipping is a complex subject.  It can happen anywhere in the production chain, and sometimes on purpose.  Most films that are clipped are done so at -1 or -2dBFS, which means that it is more likely a brick-wall limiter was used.  High-passing and shelving allows you to avoid clipping, not add to it.  See Avengers.  Shelved to avoid clipping, as many other films are.

 

 

By the way, now that I'm thinking about it, I have media to submit for measurement. I think this should have no trouble claiming 5 stars all the way around: http://www.digido.com/articles-and-demos12/13-bob-katz/13-we-have-lift-off.html

 

 

This is a live recording of a NASA Space Shuttle launch at 3 miles away. Be sure to download the 5.1 channel 24-bit 96kHz FLAC version. Note that the correct playback level is +7 relative to theatrical reference! The recording is 4 channel (front-left, front-right, surround-left, surround-right). The 5.1 channel FLAC contains silence for the LFE and center channels. According to Bob Katz, this thing has 119 dB at 25 Hz and 116 dB at 16 Hz and below.

 

On my system with multiple 16 Hz ported Hsu subs (capable of producing clean and audible bass to 12 Hz in-room), I can typically hear and appreciate the difference between 3 and 4 stars extension. While this recording sounds incredible on the system, I have no doubt my system doesn't even begin to do it justice. Those of you with walls of woofers or rotaries will likely be very pleased.

 

I will have to check this track out.  Do you know if the mic clipped at all in this recording?

 

JSS

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So maxmercy and nube, are the 5 star movies both of your top 5 movies for bass subjectively?  I'm loud and flat to 10 hz but I don't think I'd put any of those 5 in my top 5.  Star trek maybe.  The plane crash scene in Fotp is one of my favorite scenes though.

 

I agree there's more to it like room and resonance, and I put "bass impact movies" in quotations because it wouldn't necessarily be that.

 

I guess what I'm sort of thinking of is a measured system of how much total bass is in movies.  Something that would factor in length of the bass scenes and total amount of bass scenes in a movie

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Not even close. My top bass films have to be watch-able, and more importantly, re-watch-able. In other words, it has to be a good film, or a bad film with over-the-top visuals and sound to make up for it.

 

I can't order them, but my top bass films (right now):

 

TIH - best overall bass film, IMO. It is almost too much, dynamics suffer.

TF2 - best use of above 20Hz effects, tremendous slam, even more than TF1.

Scott Pilgrim - no faults except nothing below 16Hz

Rush - great film, soundtrack was perfect for imagery

Attack the Block - surprising low end

Battle:LA - another bass assault, like TIH.

9 - hard to beat in any regard

Dredd - sleeper film, great sound, tremendous visuals, could have used a better bad-guy cast, but true to the comics

Star Trek - warp booms.....engage.

HTTYD - if your system can do this justice, there is no need to upgrade, EVER, except for TF1 where Megatron blasts Jazz

Thor - best mid-bass slam in last 3 years in my room.

 

They each have something they bring, bass-wise. No film is perfect.

 

This data-bass is an objective compilation, with only 25% subjectivity.

 

The phrase 'how much total bass' is so broad it has to be delineated much more fully. The easiest way to see if a film has more 'total bass', is simply to take the area under the curve of the Avg graph for every film and whichever one is biggest wins, factoring in film length.

 

Otherwise, it's just all the opinions thrown out at AVS.

 

You cannot imagine how much resonances affect the list above, or any review anyone posts. One person's 'best' can easily be another's 'meh' because of it.

 

JSS

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Watched Captain America winter soldier this evening and what an awesome bass assault it was. Will be buying this one and five stars I would rate it. Bass was very clean and outstanding audio accompanied it. Of course I'm guessing here and will leave the data to those more capable but I loved it. Couldn't tell with my system whether or not there was anything digging down really low but felt maybe not?

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Not even close. My top bass films have to be watch-able, and more importantly, re-watch-able. In other words, it has to be a good film, or a bad film with over-the-top visuals and sound to make up for it.

 

I can't order them, but my top bass films (right now):

 

TIH - best overall bass film, IMO. It is almost too much, dynamics suffer.

TF2 - best use of above 20Hz effects, tremendous slam, even more than TF1.

Scott Pilgrim - no faults except nothing below 16Hz

Rush - great film, soundtrack was perfect for imagery

Attack the Block - surprising low end

Battle:LA - another bass assault, like TIH.

9 - hard to beat in any regard

Dredd - sleeper film, great sound, tremendous visuals, could have used a better bad-guy cast, but true to the comics

Star Trek - warp booms.....engage.

HTTYD - if your system can do this justice, there is no need to upgrade, EVER, except for TF1 where Megatron blasts Jazz

Thor - best mid-bass slam in last 3 years in my room.

 

They each have something they bring, bass-wise. No film is perfect.

 

This data-bass is an objective compilation, with only 25% subjectivity.

 

The phrase 'how much total bass' is so broad it has to be delineated much more fully. The easiest way to see if a film has more 'total bass', is simply to take the area under the curve of the Avg graph for every film and whichever one is biggest wins, factoring in film length.

 

Otherwise, it's just all the opinions thrown out at AVS.

 

You cannot imagine how much resonances affect the list above, or any review anyone posts. One person's 'best' can easily be another's 'meh' because of it.

 

JSS

 

I agree with you on those picks, those are all great.  What I'm getting at is, with all this effort being put into objective measurements, I think it could be tweaked a bit to give slightly better results.  Movies like TIH, battle:LA should be higher than Fotp and warhorse.  Resonances definitely are a big factor which is why I like this objective list.  

 

Some possibilities would be measuring level and dynamics at say 5-10 hz, 20 - 30 hz, 40-60 hz and 60-80 hz or something like that and factoring that all into the ratings.  

Factoring in the -6 dB point, -10 dB point and -20 dB points into frequency extension.  And then amount of bass in movies.  Movies with one really good scene can get really high ratings, but I think movies that have 10-20 quite good scenes should be a higher rating than a movie with one or two "perfect" bass scenes. 

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You are more than welcome to make up your own measurement system to address those issues.  I used to keep 'area under the curve' numbers for each film, but it is a slow process, and 'area under the curve' still does not yield accurate results due to FFT limitations.

 

If you want to bandpass an entire film's sound for each frequency band and post results, please do so.  But like I said before, with the PvA graph and the Peak/RMS numbers, you can have a very good idea as to how a film will sound.  If there are differences beyond that, we have an Execution Rating just for that purpose.

 

I'm serious.  Start another thread here on d-b with your methodology, and I will definitely tune in.  

 

Back to building speakers...

 

JSS

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While it sounds easy, it definitely would be very time consuming.  While the process is now much faster, we are measuring many more films (well, nube is, I haven't measured in a long time, too busy upgrading the HT).  I used to have to play the film and get the SW out from the receiver when I first started doing this, then spend about an hour putting the data together.  Now it is much less time, but what you are asking would increase the time by 10x easily (true dynamics and level for each freq band, not just area under curve).

 

JSS

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I will have to check this track out.  Do you know if the mic clipped at all in this recording?

 

JSS

 

I don't believe so.  This is the only nspace Shuttle Launch recording I've found that isn't either fake (e.g. IMAX Hubble movie) or clipped to death.  To my ears on my system, it is totally clean.  However, note that if your system cannot adequately resolve the high frequency transients from the solid rocket booster crackle, then it may sound clipped to you.

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SME said:

 

The tricky part is knowing the proper reference volume for each track. [...]

 

This is very tricky, ATSC has a system in place for determining reference level depending on the size of the room and the amount of acoustic treatment.  Tomlinson Holman posted on AVS that in smaller mix rooms, Reference level is 81dB as it 'matches' with 85dB reference in a larger room.  This is something we are likely never to know.  If an action film has >30dB dynamics, and 4 or 5 Star Level, then I am reasonably sure that it is the theatrical mix. 

 

To me, these are concerns of the playback system and not mastering process.  I believe Audyssey's room correction technology even attempts to measure and compensate for room size effects so that "0" sounds correct for a theatrical track.  From what I can see, Audyssey calibrates my system closer to the 81 dB (or rather 71 dB for a -30 dBFS rms reference signal) number.  There's no need for the studios to try to correct for this in the mix.  Most people set the playback level by ear anyway.

 

I disagree that a Blu-ray release with > 30 dB dynamics and 4 or 5 star level is necessarily a theatrical mix.  I am sure there are many cases to the contrary.  What would happen if you took Elysium and remixed it for playback at -10 dB from reference?  I don't know what the overall rms level of the film was, but subjectively speaking, I thought the movie was relatively quiet, even when played back at theatrical reference level.  I assume then, that one could remix Elysium for playback at -10 dB from reference while preserving almost all 28 dB of dynamics.  Such a mix would rate at 5 stars all-around in contrast to the 4.5 stars the film actually received.

 

Despite these points, I appreciate the simplicity of the measurements and the data presented here.  We can all agree that the system isn't perfect, and many titles effectively cheat the system in one way or another, whether by being mixed for lower playback level or containing loads of DC noise.  Considering how frequently one encounters these cheating, perhaps it would be helpful to give the subjective "execution" category more weight.

 

One additional number that I'd like to see that need not factor into the rating is the overall RMS level of the track.  Better yet, an overall equal-loudness-weighted RMS level would be even more useful.  The purpose of this metric would be to give us context for interpreting the bass numbers.  I'm not going to get excited about a 4+ star bass movie that also has a 90 dB RMS playback level, knowing that I'll likely play it back at least -10 dB from theatrical reference.  Obviously, this wouldn't exactly tell us what playback level the artist intended us to use, but some of us may not want a track at 90 dB RMS whether or not the artist intended it that way.  ("The Dark Knight Rises" comes to mind as having an infamously loud soundtrack.)

 

I realize that obtaining weighted RMS levels may slow the workflow too much.  Some day when I get around to it, I may try my own hand at analyzing these soundtracks.  Right now I lack a Blu-ray drive and appropriate software to get a clean digital rip.  If I get around to it, maybe I can add a thread for movie loudness measurements or something.  :)

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Clipping is a complex subject.  It can happen anywhere in the production chain, and sometimes on purpose.  Most films that are clipped are done so at -1 or -2dBFS, which means that it is more likely a brick-wall limiter was used.  High-passing and shelving allows you to avoid clipping, not add to it.  See Avengers.  Shelved to avoid clipping, as many other films are.

 

Giving it thought, you are most certainly right that clipping can happen just about anywhere in the production process.  If movies didn't have deadlines, perhaps the sound teams could scrub every last instance of it, but that's not reality.  That said, I generally notice much less clipping in the mixes I choose (based on subjective loudness) to play at closer to 0 dB.  Those that I listen to at around -6 dB may be clean or have clipping only in one or two scenes (e.g., HTTYD).  Many of those I listen to at -10 dB are riddled with it (like STID).  There are also "skillfully compressed" tracks that are very clean but still get played at closer to -10 dB.  (I'm thinking Looper here.)

 

Did anyone else here find "Gravity" to have a particularly loud mix?  I was thoroughly disappointed by that soundtrack (and the whole movie for that matter).  I played back my Blu-ray copy at -10 dB.  At the beginning when things first start to fall apart, the astronauts raise their voices as they panic.  I heard what sounded like extensive hard digital clipping in that dialog, which was very distracting.  I did not see the theatrical version, so I don't know if the clipping was audible there too.  Perhaps the clipping was put there intentionally by the sound team to "simulate" overloading of the radios, but I think the effect would have convinced me a lot better if they'd added some analog qualities to the clipping instead of just digitally over-driving it.  Apart from this, all the action scenes sounded very loud, harsh, and compressed to me with no interesting micro-dynamics.  Is that what an Academy Award winning soundtrack sounds like?  Or did the original soundtrack get the life squished out of it in the remixing process?

 

To pick one more example: the "Prince of Persia: The Sands of Time" Blu-ray.  I played this one back at close to "0", but I had to fix a quirk.  The center channel level was about 3 dB too high.  Presumably this 3 dB boost was done to raise the dialog level relative to the rest of the mix (for the "home environment"), and a remix from stems wasn't possible.  In any case, this Blu-ray has a phenomenal soundtrack, clean with excellent macro and micro-dynamics throughout, as is the case with most Disney releases.  I did hear one flaw though:  Right at the climax of the film, the most passionately spoken syllable of all the dialog in the film clips.  With every other utterance sounding crystal clear to me, I imagine the dialog team went through great pains to ensure the dialog track was nigh-well perfect.  So it's amusing to speculate that the Blu-ray remixers thwarted their efforts on that one syllable by boosting the center 3 dB without using a soft limiter.

 

Oh well.  I admit I may be overly sensitive to clipping.  I dabbled a lot in computer music back in the day and I learned the sound of digital clipping very well so I could avoid causing any of it.  I can't believe I've seen literature proclaim that signals can be boosted up to 20% into clipping without audible consequences.  This is the sort of reasoning that leads to egregious examples like STID.  Even compression bothers me when it's over-used.  If a loud movie scene gets compressed so much that it loses most of its micro-dynamics, then I'd much rather that scene be quieter but retain the dynamics than be loud and flat.

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There's a whole lot of speculation here, but very little to no data on which to base your conclusions.  I'd love to see an undertaking that explores these assertions.  :)  Before embarking on that, though, it would certainly help me if you could explain the exact data and methodology with which you'd test the hypotheses, because I know I would certainly appreciate the technical specifications of how to accomplish this.  Without that spec, it's hard to gauge the efficacy of a proposal...especially such a solution to a problem that I'm not sure exists.  Beyond that, an elegant solution, not merely any solution, would be the tits!  :)  I want to be wowed!

 

Also, without looking at the waveforms, how can you accurately assess clipping when it's not frequent or egregious?  I'd love some tips.  :)  Are you 100% certain it's not your system, signal chain, or room?  Speaking of, can you give the specifics and maybe some pics/measurements so we can see what sort of equipment you're working with?  I love reading about people's very capable systems!

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While it sounds easy, it definitely would be very time consuming.  While the process is now much faster, we are measuring many more films (well, nube is, I haven't measured in a long time, too busy upgrading the HT).  I used to have to play the film and get the SW out from the receiver when I first started doing this, then spend about an hour putting the data together.  Now it is much less time, but what you are asking would increase the time by 10x easily (true dynamics and level for each freq band, not just area under curve).

 

JSS

Ah ok.  I'm not sure on the programs full functionality so I wasn't sure if that was something that could be automated.

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To me, these are concerns of the playback system and not mastering process.  I believe Audyssey's room correction technology even attempts to measure and compensate for room size effects so that "0" sounds correct for a theatrical track.  From what I can see, Audyssey calibrates my system closer to the 81 dB (or rather 71 dB for a -30 dBFS rms reference signal) number.  There's no need for the studios to try to correct for this in the mix.  Most people set the playback level by ear anyway.

 

This is not surprising.  Chris Kyriakis, the Audyssey guru was one of Tomlinson Holman's grad students.  Audyssey was essentially his idea, and since Holman believes that 81dB in smaller room = 85dB in cinema, there you go.  Older Audyssey firmware uses 85dB as reference. 

 

The Reference Level at which a track is mastered has everything to do with how the mix is created.  A home mix done at a lower reference level will likely have less dynamics, and dialogue will be encoded at a higher dBFS.  It is not as simple as 'playback by ear'.  Otherwise, mixers would simply use the theatrical reference and turn it down by 4dB.  Done.

 

Here is the ATSC paper, good reading:

 

http://www.atsc.org/cms/standards/A_85-2013.pdf

 

I disagree that a Blu-ray release with > 30 dB dynamics and 4 or 5 star level is necessarily a theatrical mix.  I am sure there are many cases to the contrary.  What would happen if you took Elysium and remixed it for playback at -10 dB from reference?  I don't know what the overall rms level of the film was, but subjectively speaking, I thought the movie was relatively quiet, even when played back at theatrical reference level.  I assume then, that one could remix Elysium for playback at -10 dB from reference while preserving almost all 28 dB of dynamics.  Such a mix would rate at 5 stars all-around in contrast to the 4.5 stars the film actually received.

 

Like I said, different mix, likely different dynamics numbers.  Only if you can A-B the theatrical vs the home mix can you make such a claim.  A few films advert that they have the theatrical mix within them.  There are measurable differences, which cannot be accounted for by a simple 'turn it up by 4dB' adjustment.

 

Despite these points, I appreciate the simplicity of the measurements and the data presented here.  We can all agree that the system isn't perfect, and many titles effectively cheat the system in one way or another, whether by being mixed for lower playback level or containing loads of DC noise.  Considering how frequently one encounters these cheating, perhaps it would be helpful to give the subjective "execution" category more weight.

 

Then we would be at AVS.  The primary reason this thread was started was due to the overwhelming support The Avengers got as a 'great bass film' over at AVS, when it was quite clear it left a lot on the table under 30Hz, and to let the data speak for itself, with subjectivity taking a distant second.

 

One additional number that I'd like to see that need not factor into the rating is the overall RMS level of the track.  Better yet, an overall equal-loudness-weighted RMS level would be even more useful.  The purpose of this metric would be to give us context for interpreting the bass numbers.  I'm not going to get excited about a 4+ star bass movie that also has a 90 dB RMS playback level, knowing that I'll likely play it back at least -10 dB from theatrical reference.  Obviously, this wouldn't exactly tell us what playback level the artist intended us to use, but some of us may not want a track at 90 dB RMS whether or not the artist intended it that way.  ("The Dark Knight Rises" comes to mind as having an infamously loud soundtrack.)

 

That brings up a whole new problem.....LeqA, LeqC, LeqZ, or just digital RMS?  A film dialogue heavy with very loud scenes will always measure out with a lower RMS than an all action oriented film that is non-stop loud, but at a much lower level.  Both could have identical Leq numbers. 

 

I realize that obtaining weighted RMS levels may slow the workflow too much.  Some day when I get around to it, I may try my own hand at analyzing these soundtracks.  Right now I lack a Blu-ray drive and appropriate software to get a clean digital rip.  If I get around to it, maybe I can add a thread for movie loudness measurements or something.  :)

 

I will definitely tune in.

 

 

Giving it thought, you are most certainly right that clipping can happen just about anywhere in the production process.  If movies didn't have deadlines, perhaps the sound teams could scrub every last instance of it, but that's not reality.  That said, I generally notice much less clipping in the mixes I choose (based on subjective loudness) to play at closer to 0 dB.  Those that I listen to at around -6 dB may be clean or have clipping only in one or two scenes (e.g., HTTYD).  Many of those I listen to at -10 dB are riddled with it (like STID).  There are also "skillfully compressed" tracks that are very clean but still get played at closer to -10 dB.  (I'm thinking Looper here.)

 

If a sound is clipped at the mic when recording, it will always be clipped.  You need a clena recording to begin with, and ensure that no clipping occurs during the multiple manipulations afterwards, unless it is purposeful.  As much as I have tried 'unclipping' and 'de-compressing' certain tracks, the end result is always poor.  You can't extrapolate data that is missing very well.

 

Did anyone else here find "Gravity" to have a particularly loud mix?  I was thoroughly disappointed by that soundtrack (and the whole movie for that matter).  I played back my Blu-ray copy at -10 dB.  At the beginning when things first start to fall apart, the astronauts raise their voices as they panic.  I heard what sounded like extensive hard digital clipping in that dialog, which was very distracting.  I did not see the theatrical version, so I don't know if the clipping was audible there too.  Perhaps the clipping was put there intentionally by the sound team to "simulate" overloading of the radios, but I think the effect would have convinced me a lot better if they'd added some analog qualities to the clipping instead of just digitally over-driving it.  Apart from this, all the action scenes sounded very loud, harsh, and compressed to me with no interesting micro-dynamics.  Is that what an Academy Award winning soundtrack sounds like?  Or did the original soundtrack get the life squished out of it in the remixing process?

 

Good question.

 

To pick one more example: the "Prince of Persia: The Sands of Time" Blu-ray.  I played this one back at close to "0", but I had to fix a quirk.  The center channel level was about 3 dB too high.  Presumably this 3 dB boost was done to raise the dialog level relative to the rest of the mix (for the "home environment"), and a remix from stems wasn't possible.  In any case, this Blu-ray has a phenomenal soundtrack, clean with excellent macro and micro-dynamics throughout, as is the case with most Disney releases.  I did hear one flaw though:  Right at the climax of the film, the most passionately spoken syllable of all the dialog in the film clips.  With every other utterance sounding crystal clear to me, I imagine the dialog team went through great pains to ensure the dialog track was nigh-well perfect.  So it's amusing to speculate that the Blu-ray remixers thwarted their efforts on that one syllable by boosting the center 3 dB without using a soft limiter.

 

Oh well.  I admit I may be overly sensitive to clipping.  I dabbled a lot in computer music back in the day and I learned the sound of digital clipping very well so I could avoid causing any of it.  I can't believe I've seen literature proclaim that signals can be boosted up to 20% into clipping without audible consequences.  This is the sort of reasoning that leads to egregious examples like STID.  Even compression bothers me when it's over-used.  If a loud movie scene gets compressed so much that it loses most of its micro-dynamics, then I'd much rather that scene be quieter but retain the dynamics than be loud and flat.

 

I am as well, at least I think I am.  It is immediately obvious to me sometimes.

 

 

See above.

 

JSS

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There's a whole lot of speculation here, but very little to no data on which to base your conclusions.  I'd love to see an undertaking that explores these assertions.  :)  Before embarking on that, though, it would certainly help me if you could explain the exact data and methodology with which you'd test the hypotheses, because I know I would certainly appreciate the technical specifications of how to accomplish this.  Without that spec, it's hard to gauge the efficacy of a proposal...especially such a solution to a problem that I'm not sure exists.  Beyond that, an elegant solution, not merely any solution, would be the tits!  :)  I want to be wowed!

 

Also, without looking at the waveforms, how can you accurately assess clipping when it's not frequent or egregious?  I'd love some tips.  :)  Are you 100% certain it's not your system, signal chain, or room?  Speaking of, can you give the specifics and maybe some pics/measurements so we can see what sort of equipment you're working with?  I love reading about people's very capable systems!

 

Thanks for your observations.  Yes, almost everything I stated above is speculative and/or subjective.  I am also interested to see if I can support or reject any of these statements with good data.  I am a programmer and am capable of writing the necessary data analysis tools myself.  The main barrier to me doing this is decoding the audio bitstream to PCM from the discs, which may not be possible on my Linux systems.  Anything I have to use Windows to do makes me move a lot slower.  :)

 

As for systematically detecting clipping, that's a harder proposition.  Harder is proving (or disproving) my hypothesis that a lot of clipping gets introduced in the "made for home" remix process.  It would be very interesting to see data that compares the "made for home" and theatrical mixes on those Blu-rays that offer a choice, that is if I could find any such Blu-rays.

 

Edit: I previously misstated that "Oz the Great and Powerful" and "The Fifth Element" have copies of the theatrical mix on the disc.  Upon closer review, that does not appear to be the case for either title.

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Watched Captain America winter soldier this evening and what an awesome bass assault it was. Will be buying this one and five stars I would rate it. Bass was very clean and outstanding audio accompanied it. Of course I'm guessing here and will leave the data to those more capable but I loved it. Couldn't tell with my system whether or not there was anything digging down really low but felt maybe not?

Looking forward to this one. Gotta ways to go as it is slated for September 9th. I have not really seen anything that good since Lone Survivor. Hope this one is a winner. 

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Thanks for your observations.  Yes, almost everything I stated above is speculative and/or subjective.  I am also interested to see if I can support or reject any of these statements with good data.  I am a programmer and am capable of writing the necessary data analysis tools myself.  The main barrier to me doing this is decoding the audio bitstream to PCM from the discs, which may not be possible on my Linux systems.  Anything I have to use Windows to do makes me move a lot slower.  :)

 

As for systematically detecting clipping, that's a harder proposition.  Harder is proving (or disproving) my hypothesis that a lot of clipping gets introduced in the "made for home" remix process.  It would be very interesting to see data that compares the "made for home" and theatrical mixes on those Blu-rays that offer a choice.  Until I can get at the data, I can at least do A/B comparisons to try to figure out what changed.

 

I currently own "The Fifth Element" and "Oz: The Great and Powerful", both of which claim to provide both mix types.  I really should A/B those mixes some time.  WIth TFE, I thought the theatrical mix sounded great at "0" with an X-curve EQ target curve.  With OTGAP, I watched with the "near-field" mix, and thought "-10" was plenty, even though the "correct" playback level may be higher.  I also thought some of the more dynamic sounds seemed a tad harsh and slightly exaggerated.  It will be interesting to listen to the alternate mixes for both of these titles.  I'm particularly curious about the theatrical track to  OTGAP, given that I played the near field mix back at such a low level.

 

Hey, I guess what I was after is what data would you use, specifically, and how would it be obtained/manipulated?  Like, would you mind expressing it in a formula?

 

I find myself very sensitive to clipping, "harsh" sounds, and very low bass, but I can't really quantify it in words.  Looking at the waveforms tells us the truth of whether it's clipped/compressed/limited.  Besides that, it's hard to prove other than it just sounds bad (which sometimes is by design).  I was hoping you had some qualitative tips on how you recognize clipping, especially if it's just one note/syllable in an entire mix.

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Just wanted to thank the guys for mentioning when a movie has good mid-bass impact.  Some of us (or maybe I'm the only one in this thread  :D ) only have subs that only reach down to 25Hz.  Thanks!

 

 

I'm guessing here but the new Captain America could be suitable.

 

Looking forward to this one. Gotta ways to go as it is slated for September 9th. I have not really seen anything that good since Lone Survivor. Hope this one is a winner. 

 

 

What's with the release date on this movie? I'm in Australia and we're normally about six weeks behind down under. Is the release scheduled for Sept 9th in the States? If so wonder why so late. God I look like a fanboy for this film. :lol:

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This is not surprising.  Chris Kyriakis, the Audyssey guru was one of Tomlinson Holman's grad students.  Audyssey was essentially his idea, and since Holman believes that 81dB in smaller room = 85dB in cinema, there you go.  Older Audyssey firmware uses 85dB as reference. 

 

The Reference Level at which a track is mastered has everything to do with how the mix is created.  A home mix done at a lower reference level will likely have less dynamics, and dialogue will be encoded at a higher dBFS.  It is not as simple as 'playback by ear'.  Otherwise, mixers would simply use the theatrical reference and turn it down by 4dB.  Done.

 

Here is the ATSC paper, good reading:

 

http://www.atsc.org/...s/A_85-2013.pdf

 

[...]

 

 

That brings up a whole new problem.....LeqA, LeqC, LeqZ, or just digital RMS?  A film dialogue heavy with very loud scenes will always measure out with a lower RMS than an all action oriented film that is non-stop loud, but at a much lower level.  Both could have identical Leq numbers. 

 

 

Thanks for the link to the paper.  It is a very good read.  I do question their Table 10.2 specifying the SPL to calibrate to as a function of room size alone.  I believe it doesn't depend on room size at all but rather on other factors that tend to roughly scale with room size.  Other considerations include room treatment, speaker distance, and speaker dispersion.  I'm guessing that a near-field monitoring setup, even in a very large room, should still be treated as a system in a small room and calibrated to, e.g. 76-78 dB (versus 85 dB for large rooms).  So if the mixers followed the guidelines in this table, it's certainly possible that a film could be mastered as much as 9 dB below theatrical reference.

 

Now about so-call near-field mixes.  I don't object to their creation, but I'm not convinced that all the changes made in these mixes improve the final result.  I also fear they are frequently performed on middling equipment under the assumption that it's "closer to what consumers are using".  Let me review the changes made during the near-field mixing process, according to what I've gathered from other forums:

  1. Corrections are made to account for the use of discrete surround speakers in most home systems as opposed to the diffuse arrays of surrounds used in theaters and dubbing stages.  I fully support this work, and with Atmos coming, dipole surrounds having diffuse sound are quickly becoming obsolete.
  2. The dialog level is often boosted.  I understand that this is done to improve dialog intelligibility on many real world playback systems, many of which may be badly mis-configured or have severe acoustical problems.  Apart from these cases, I think the reason a lot of people complain about dialog intelligibility is that the macro-dynamic range of the track is too high for their system or playback environment.  Some people ride their volume controls between quiet and loud parts of the movie while others just resign themselves to not being able to hear what's said on screen.  My hunch is that family movies are likely to get the most dialog boost, so the kids can follow along even when they are playing softly.  See below for my comments on dynamic range.
  3. Overall levels are reduced.  Admittedly, it's not 100% clear to me what this statement means.  I usually take it to mean that the playback level used during the remixing process was reduced.  Another interpretation would be that the level of the digital signal, relative to full-scale, was reduced.  More to say on this later.
  4. Dynamic range is reduced.  This I don't agree with at all.  Why does dynamic range get reduced?  Nothing in that ATSC article says anything about reducing the dynamic range of a signal when reproducing it in a smaller room.  If someone wants to argue that consumer systems can't handle the full theatrical dynamic range, or that consumers will complain, that's fine, but the solution(s) to this problem are dynamic range compression in the playback device and/or a separate "made for TV speakers" mix with substantially reduced dynamics all around.

Did I miss anything important?

 

Okay.  Let me point out that if dynamic range is intentionally reduced in the "made for home" mix, for whatever reason, the sound quality will be damaged, unless it had poor dynamics to begin with.  If the dynamic range reduction is done poorly, clipping can result.  If it is done skillfully and the reduction isn't too much, the quality loss may only be subtle on the best of systems.  I've heard plenty of soundtracks that I thought sounded compressed but nevertheless sounded very clean and good.

 

What if dynamic range is not intentionally reduced.  Can clipping happen in the remixing process?  I think the answer is a strong yes.  Here's how I can see it happening:  The "near-field" mix room and system are calibrated for a reduced playback level, say 79 dB.  This level may have been chosen based on any number of factors such as recommendations from Table 10.2 in the article you sent, similar guidelines published elsewhere, or even just hearsay recommendations from others in the industry.  The point is if this level was chosen to be too low, the mixers will be inclined to push the faders up to bring things in line with the theatrical presentation, potentially causing things to clip if they don't have softer limiting somewhere in the chain.

 

That's not all.  Remember what I said about the frequency response curve?  Suppose 79 dB is the right calibration level in this studio for pink noise between 500-2000 Hz, but the bass is too weak at this level without some EQ to boost the bass.  So again, the mixers push faders up to bring the bass into proper balance.  Unfortunately, the bass is usually the strongest signal present in the soundtrack, so clipping is especially likely when this is done.  This can be partly mitigated using bass management tricks like re-directing the bass to different channels.  I imagine that this process is often very time consuming, and given the reality of tight schedules and deadlines, compromises are inevitable.  Options might include high pass filtering (to free up headroom), accepting some clipping, or just leaving the bass levels reduced.

 

One more thing to mention is that some "mode for home" mixes may be rejected and re-done simply because they don't sound loud enough at "volume setting XX" on someone's AVR.  As much as I wish that the madness of the Loudness War did not infect the world of film, it seems unavoidable.

 

============

 

As for what kind of weight to use for integrated loudness measurements, I think the K-weighting discussed in the ATSC paper is probably a good place to start.  I think it would be interesting to look at loudness and loudness dynamics over a few different time scales.  I haven't followed up on the reference for evaluating LKFS yet, so I don't know how readily available that paper is, but the technique appears to be fairly simple while taking into account the bulk of the relevant psychoacoustic phenomena involved in loudness perception.

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Hey, I guess what I was after is what data would you use, specifically, and how would it be obtained/manipulated?  Like, would you mind expressing it in a formula?

 

I find myself very sensitive to clipping, "harsh" sounds, and very low bass, but I can't really quantify it in words.  Looking at the waveforms tells us the truth of whether it's clipped/compressed/limited.  Besides that, it's hard to prove other than it just sounds bad (which sometimes is by design).  I was hoping you had some qualitative tips on how you recognize clipping, especially if it's just one note/syllable in an entire mix.

 

As I described in another recent post, I would probably use something similar or even identical to the LKFS approach outlined in the ASTC paper to do loudness measurements.

 

I'm not exactly sure how to answer your question about how to qualitatively identify clipping.  Are you looking for a way to identify it by listening, by visually inspecting the wave form, or by using some kind of analytical technique?  I can describe what I think clipping sounds like, but I'm not sure if that's the answer you're looking for.

 

I pointed out the clipping I thought I heard on a single syllable of dialog in "Prince of Persia" because it stood out.  Many films including almost all made more than a decade or so ago are riddled with clipping throughout the dialog.  The human voice is very dynamic and difficult to record.  For various reasons, this clipping tends to be fairly mild, and since it is so common in recorded voice, we don't tend to notice it much if at all.  But with  "Prince of Persia" that one little pop stood out like a sore thumb because the rest of the dialog was so crystal clear.

 

Granted, I cannot 100% rule out the possibility that my equipment introduced the clipping.  I seriously doubt it, but at the time, I did not do the "playback at lower level" test that I often do to make sure it's not my system.  Thus far, each time I've suspected my system of having introduced the clipping, I've either disproved this suspicion confirming I still hear  it in low level playback or found confirmation in this forum that the clipping is in the soundtrack.  My amp also is supposed to illuminate red LEDs when it clips, and it has yet to do so, although I know little of the specifics of how its clip detection mechanism works.  Realizing that clipping is fairly common in Blu-ray soundtracks, I've all but stopped worrying about what my system is doing.

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I'm guessing here but the new Captain America could be suitable.

 

 

 

What's with the release date on this movie? I'm in Australia and we're normally about six weeks behind down under. Is the release scheduled for Sept 9th in the States? If so wonder why so late. God I look like a fanboy for this film. :lol:

Seems anymore it is about 5 months for a title to hit the shelves. I guess it all depends how the movie does at the box office. Maybe did better in another country and ran longer and held it up. Dunno  :unsure: X men Days of future past came out in May is not due out till Oct 14th, however Transformers came out in late June but is scheduled for September 30th. 

 

 I just wish they would get all the movies on par and release them all at the same time. I hate hearing people talking about movies before we get them in the States. I am sure there is a reason, but I would like to know why. 

 

Also, yes CA is supposed to be released Tuesday Sept 9th. 

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The Double (5.1 DTS-HD MA)

 

Level        - 2 Stars (107.1dB composite)
Extension - 3 Stars (15.5Hz)
Dynamics - 5 Stars (33.39dB)

Execution - 3 Stars (by poll)

 

Overall     - 3.25 Stars

Recommendation - Rent (by poll)

 

Notes:  From the beginning, there's a lot of low level content below 10Hz, and some from 10-20Hz.  Seems like a couple of low shelf filters were applied.  Not much of a bass movie, but excellent dynamics.

 

PvA:

 

post-17-0-64126000-1409160360_thumb.png

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