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Dolby TrueHD with Advanced 96k Upsampling: First Impressions (1 Viewer)

DavidJ

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Hal F said:
I actually think 'skepticism' is a rather mild word to use in the circumstances. And until Dolby is willing to set up some double-blind tests conducted by independent experts one is certainly entitled to that skepticism.
If you do some reading in the psychoacoustic literature you will soon learn how easy it is to be deceived by one's audio impressions. One book that I would highly recommend is: "Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms" by Floyd Toole.
Thanks for the book recommendation. I've read a decent amount on the subject, but I missed that one.
 

Adam Gregorich

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Originally Posted by moovtune /t/320857/dolby-truehd-with-advanced-96k-upsampling-first-impressions#post_3928599
I'm not following how the mixers will be able to audition the results of this process. The encoding to True HD is not done on the mixing stage but I assume by the editors in the home video department in prep for a Blu-Ray release. And if it's a filter that works best with higher sample rates (96K), then the mixers, working at 48K, wouldn't have access to the improvement during their work on the mix. That would only come later during the encode process right? Well after the mix is done.
Yes. It is first encoded for theatrical playback, at 48k and then that mix is sometimes remixed before its encoded for home video release.
 

Douglas Monce

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Adam Gregorich said:
Yes.  It is first encoded for theatrical playback, at 48k and then that mix is sometimes remixed before its encoded for home video release.
So again you're not hearing what the sound designers and mixers heard and planned for.
Bad!
Doug
 

RobertR

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This seems more like marketing than a genuine advance. As Hal pointed out, double blind comparisons would be needed to show a genuine difference. There was a large double blind study showing that "hirez" audio doesn't really sound better.
 

Yorkshire

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A few questions.
1 - By removing the 'pre-ringing' will this also remove pieces of audio information which are not artefacts and which are supposed to be there, in the same way that DNR does its job, but also removes grain and high frequency detail?
2 - Can we have a double blind test?
3 - Can the above be done on a variety of pieces popular home cinema equipment? It'd be interesting to see if any difference can be heard on anything other than extremely high end kit.
Steve W
 

Adam Gregorich

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Originally Posted by Yorkshire /t/320857/dolby-truehd-with-advanced-96k-upsampling-first-impressions#post_3928956
A few questions.
1 - By removing the 'pre-ringing' will this also remove pieces of audio information which are not artifacts and which are supposed to be there, in the same way that DNR does its job, but also removes grain and high frequency detail?
2 - Can we have a double blind test?
3 - Can the above be done on a variety of pieces popular home cinema equipment? It'd be interesting to see if any difference can be heard on anything other than extremely high end kit.
Steve W
1) It doesn't

2) See number 3

3) I'd be very interested in seeing that. We told Dolby that they really needed to have a comparison clip put on a publicly available disc or create a demo disc so that people can hear the difference for themselves on their own system. This would allow people to set up double blind tests and try it out on different levels on equipment. As of now you will get a disc with the upsampling sticker on the packaging, and yes it will sound good, but how will you know if it actually sounds better than the 48k version if you have never had a chance to compare them? Please note that they haven't said they would do this, but it was the advice HTF gave them.
 

RobertR

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Adam Gregorich said:
We told Dolby that they really needed to have a comparison clip put on a publicly available disc or create a demo disc so that people can hear the difference for themselves on their own system.  This would allow people to set up double blind tests and try it out on different levels on equipment.  As of now you will get a disc with the upsampling sticker on the packaging, and yes it will sound good, but how will you know if it actually sounds better than the 48k version if you have never had a chance to compare them?  Please note that they haven't said they would do this, but it was the advice HTF gave them.
I'm very glad to hear they were given that advice.
 

Douglas Monce

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Adam Gregorich said:
1) It doesn't
2) See number 3
Of course you don't know this to be true. You only have Dolby's word for it, and no impartial organization has had the opportunity to test it.
Doug
 

bigshot

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Adam Gregorich said:
Actually its nothing like that.  Preringing is an unnatural artifact introduced as a byproduct of the D to A conversion.  Its not present in an analog recording (assuming a complete analog path).  Meridian (and now Dolby) use the apodizing filter to remove the distortion that was artificially introduced, to make it sound more like the original analog source. It sounds much more natural having been run through the filter. 
The problem with general knowledge about digital audio is that the terms used to describe things are often analogies that are completely deceiving. "Preringing" sounds like a sound that echoes, "brick wall filters" sound like sound is being chopped off, and "jitter" sounds like some sort of vibration in the sound. When you read up on the science behind the terms, you realize that the scale of the effect is so small, it isn't audible, and it just doesn't matter... except to salesmen who want to make Brand A look better to the unsuspecting consumer than Brand X.
Preringing affects soundwaves that jump from nothing to a big modulation instantaneously. Music and movies don't contain huge leaps like that. Even if it did, your speakers would not be able to reproduce the distortion, because a paper cone can't respond that fast to a jump in level. The speaker itself is an apodizing filter.
Preringing is not a recent discovery. It's been identified and dealt with already. You don't have to upsample to ridiculous rates to correct it.
Assuming Dolby has really discovered some new, previosly undiscovered sort of artifact, why would they not put an A/B sample on a bluray so everyone can hear the difference? I can only think of two reasons...
1) People with technical knowhow and the necessary equipment would be able to rip the "before and after" tracks and compare the waveforms... and discover they actually aren't the same signal.
2) People would have access to the comparison who aren't enjoying the afterglow of a nice free lunch, interesting technical presentation and fancy leather chairs in expensively furnished listening rooms to color their impressions.
 

bigshot

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Douglas Monce said:
Apodizing. Hmmmmm Sounds like the audio equivalent to motion smoothing.
No, it's really not like that. It's a distortion created by the error in sampling when a waveform goes from "zero to sixty" in a space of time too small for the sampling to define it. Some of the modulation spills over into the adjacent sample.
The thing is, a sample is so brief, you can't perceive it, and no sound in the real world goes from nothing to full modulation that fast. Apodizing filter or not, it's not really audible.
It's not at all like 30 frames per second being interlaced up to 60 frames per second. It's operating in a tiny fraction of time thousands of times smaller than that. It's not like a broadband noise reduction filter either. It's just cleaning up the tiny bit of error between samples. It's more like crossing theoretical t's and dotting theoretical i's that don't matter because you'll never notice it in the real world.
Here is what we know from the person who was at the demonstration...
Some people heard a difference in high frequencies, others in midrange dialogue. Some heard it in the sharp transients of a drumstick countoff, others in the slow ring out of Also Sprach Zaruthrustra.... Everyone seemed to hear a difference in different clips and different parts of the sound...
I'm betting on the free lunch.
 

ChuckZ

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I'm really disappointed that Dolby is shlocking this "technology" as science. They develop such wonderful technologies and products, but this is totally scraping the barrel of what constitutes audible improvement.
Others have already alluded to the poor testing procedures. I'll simply add that 48 kHz is all we'll ever need as homo sapiens. 96 kHz is a myth (like Dry Land). :P
 

bigshot

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Don't blame Dolby. They're just doing what every other company in home audio does. When sound becomes perfect, every brand sounds the same. They have to do something to diffentiate themselves in the market.
 

Dcbingaman

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Meridian processors have been using apodizing filters for several years, and sound demonstrably better than ANYTHING else on the market. Preringing is very audible and irritating to those who are sensitive to it, similar to rainbows on DLP projectors. This is the exact same phenomena that makes D/A conversion at 96khz preferable to 44.1khz - it pushes the ringing out of the audible range.
In my experience with the Meridian processors, the improvement for CD sources is much more pronounced than for Blu-Ray or higher sample-rate audio, and makes CD's sound almost indistinguishable from SACD and DVD-A recordings of the same program material.
Dolby should be commended for using Meridian's A/D filters, but don't be surprised if DTS does the same thing, or comes up with a similar A/D filter for their Master Audio product.
 

lukejosephchung

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Originally Posted by bigshot /t/320857/dolby-truehd-with-advanced-96k-upsampling-first-impressions/30#post_3932993
CDs sound indistinguishable from SACDs anyway.
To YOUR ears...not to mine!!! I've heard upsampled material on my Denon AVR-4311 Receiver and hear the difference as a considerably less harsh sounding digital presentation than conventional 44.1/48k playback!!!
 

bigshot

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I'll bet you ten bucks the master used for the redbook layer was different than the SACD layer, and you didn't do a line level match or direct A/B switching.
Very few SACDs have the same mastering on both layers. When I did my own comparison test, it took about ten to find a label that didn't deliberately hobble the redbook layer (Pentatone). I also found out that the SACD layer is always noticeably louder. I couldn't find an SACD player that didn't have a long delay when switching layers, so it took two players. Once I had chased all those bugaboos down, neither I nor a sound mixer friend could detect any difference on professional playback equipment.
The SACD format is designed to fool you into thinking it's an improvement, but all of the improvements of high bitrate sound aren't audible in normal listening situations. All of the increased resolution is in extremely quiet sounds. You would have to turn the volume on your stereo up to the point where you would incur hearing damage at the peaks to hear the benefit of SACD. The resolution at normal listening volumes is identical.
 

Dcbingaman

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For stereo material which was sampled at 48k, the difference between a good CD and an average SACD is relatively small and may not be noticeable for many listeners with commonly used equipment. To my ears, a good apodizing filter upstream of the reconstruction filter eliminates the difference on SOTA systems, (ie, Meridian, BAT, Vandersteen, etc.)
An EXCELLENT classical SACD has an advantage you cannot hear on a CD - 5.1 surround sound. This makes a huge difference and makes Mch SACD's, DVD-A's (RIP), and Blu-Ray discs much more satisfying than stereo CD's.
Only vinyl, sampled at 24 bit / 96 khz and Upmixed to 3.1 via Trifield or 5.1 via DTS Neural technology, comes close.
 

bigshot

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5:1 is a major thing. Probably the only real sound quality improvement since the introduction of stereo in the mid 50s.
I love records. I have over 15,000 of them dating back 100 years. But I have to admit that properly digitized, a regular CD can contain every bit of the sound, even on the best recorded, mastered and pressed records. I tested this using a pristine Lincoln Mayorga Sheffield Lab direct to disk. The CD was identical.
 

Roogs Benoit

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Back to the Dolby 96K upsampling technology...
I know you are complaining about no blind test etc and think that Dolby is up to something tricky here. The fact is that the test may not have been a perfect test and your milage will vary. But, Dolby has given this technology to many facilities and studios to do their own tests with their own material. The facts will soon come out and I'm hoping for the best.
It's a big win for the consumers who can have this improved audio quality without having to wait or buy new gear. If your receiver decodes Dolby TrueHD it will be able to play this back too. It's in the processing before (actually during) the encode so the decoder doesn't have to do anything new. Except maybe light up the 96K light on your receiver.
The reason this is done in the encoding stage using the Dolby MP is because if you could do this to your .wav files, there would be nothing stopping people from doing that and encoding their files as DTS.
Would be interesting if they could bring this to Digital Cinema and if there would be any noticeable improvement in a theater setting with 400 of your closest friends.
 

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