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Why is MPC perceived to be the best?, (an off-topic audio encoding discussion)
ScorLibran
post Feb 8 2004, 18:43
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This is a question that has floated through my mind for most of a year, but only yesterday became more clear to me.

Actually, it's a two-part question...

... 1. Is MPC commonly accepted among the HA community as the best psychoacoustic encoding format? (i.e., the most efficient at achieving perceptual transparency.)

... 2. If so, why?

The first item I've heard stated quite frequently, but have never seen any results of "transparency threshold tests" that would reveal the superior efficiency of MPC. I've heard that MPC uses superior encoding technology, but I'm referring more to the end result of such development efforts...the perceived sound quality, as measured against other codecs at the point of perceptual transparency for a significant number of people.

These concerns on my part were born from a post I made here, where the points of MPC statistically tying other formats at 128kbps, but no other known test results existing, were brought up. The thread portion ended up in the recycle bin, but I'm taking the chance that my concerns about calling MPC "the best" weren't the reason it was put there.

Hence, I want to bring up this idea in a different context in the off-topic forum (in the hope that this will be the correct area for it).

What I'd like to see, for instance, for the education of myself and others, would be a results summary like the following (though this is a very simplistic example)...

Format............Perceptual Transparency Threshold (nominal bitrate across samples tested)
MPC.................nnn kbps
AAC.................nnn kbps
Vorbis..............nnn kbps

...and so forth

Granted, VBR is more efficient at mid-bitrates and up, and quality-based VBR modes aren't bitrate centric, but we need some means of measurement and comparison between codecs in this context, so if not calling it "nominal bitrate", then perhaps "average filesize per minute of audio across all samples"

Perceptual Transparency Threshold could have a fixed target, like >90% samples with 5.0 subjective ratings, and non-differentiable from reference with ABX testing.

This kind of test has been discussed before, and has been mostly viewed as having little "real-world value". And I agree. Roberto's tests are much more relevant for most music listeners, and for determining the best formats for useful purposes like streaming audio, portable players, etc.

Many of us (including me) have trouble testing even these bitrate ranges, so higher ones would be even more tedious, and would answer not as many pressing questions.

My point, though, is how can MPC be called "the best for achieving transparency" without a test such as this? (Because so far it's been shown to be only "among the best" at lower rates.)
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Kalamity
post Feb 10 2004, 02:59
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QUOTE (ScorLibran)
QUOTE (Kalamity @ Feb 9 2004, 03:00 AM)
Some of these codecs have an 'advertised' setting that is supposed to be transparent, coincidentally averaging around 160-200kbps. Perhaps holding them to this would be appropriate here?
True, but I would not base this test on how the codecs are marketed. They can call whatever they like "transparent" or "CD quality". But ABX results don't lie. wink.gif

My point was perhaps missed. You will need to start somewhere, preferably close to the threshold of transparency to save time. By starting from a particular codec's 'advertised' transparent setting, you immediately put to test the veracity of this claim. By 'advertised' I mean using official encoder settings, like with Nero's AAC Transparent, as well as common knowledge settings like Vorbis Q6 and MPC Q5. Later tests would merely isolate the general location of this threshold. This would be a fair starting point for all involved. If an 'advertised' transparent setting is used, no claims of bias could be lodged. Transparent is transparent is transparent; if someone can hear the difference, then this claim is false. If this happens to result in some codecs utilizing an overly high bitrate, then so be it. The next test (below) will show if this was truly necessary.
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QUOTE (Kalamity @ Feb 9 2004, 03:00 AM)
A pass or failure would determine an appropriate direction (lower or higher) for a second test to determine operational tolerance.

That's exactly what I had in mind.

This is the merely the second step of the above process, to follow the above initial step. Neither tests are intended to stand solely by themselves, although claims of transparency could be proven or disproven for the settings used in the first step.

As to issues of encoder version variance: establish a cutoff point (such as today) where only the major or stable versions of official encoders that were generally available as of that date will be used. Valid or not, the assumption can be made that later encoder releases should, if nothing else, be no worse than prior versions. Maintain the test as a snapshot of the world of audio compression on this, a normal and unimportant day.

Talk of 3 or more settings used per codec is already making my ears ache and my mind wander. Keeping the test groups to a small, friendly number would open your test up to a larger and more active, audience. This would be good for maintaining relevance. Anything else would merely be a test of those few indvididuals willing to stick it out, and they will almost be guaranteed to break the curve (you know who you are).

This post has been edited by Kalamity: Feb 10 2004, 03:04
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Posts in this topic
- ScorLibran   Why is MPC perceived to be the best?   Feb 8 2004, 18:43
- - sthayashi   1) The answer appears to be yes. 2) This result ca...   Feb 8 2004, 19:53
- - Canar   There's never been a hard and fast test as to ...   Feb 8 2004, 21:51
- - ScorLibran   Thanks for the input, guys. If nothing "f...   Feb 8 2004, 22:52
- - Canar   The smartest way to do it would be to encode the p...   Feb 8 2004, 23:13
- - ddrawley   The proof of MPC quality is neither vague nor simp...   Feb 9 2004, 03:38
- - Eli   Its more than the quality of the codec that draws ...   Feb 9 2004, 03:45
- - rjamorim   QUOTE (ScorLibran @ Feb 8 2004, 07:52 PM)If n...   Feb 9 2004, 04:07
- - indybrett   This is what I would like to see compared. It woul...   Feb 9 2004, 05:09
- - ScorLibran   QUOTE (rjamorim @ Feb 8 2004, 10:07 PM)QUOTE ...   Feb 9 2004, 07:36
- - Kalamity   Looks like double-nested QUOTES puts the auto-quot...   Feb 9 2004, 09:00
- - 2Bdecided   Just how many people are going to give you anythin...   Feb 9 2004, 12:51
- - Der_Iltis   Is there any site you would suggest where i can fi...   Feb 9 2004, 17:04
- - bubka   QUOTE (indybrett @ Feb 8 2004, 11:09 PM)This ...   Feb 9 2004, 17:08
- - sthayashi   QUOTE (ScorLibran @ Feb 9 2004, 01:36 AM)How ...   Feb 9 2004, 17:47
- - music_man_mpc   This problem has bothered me as well in the past. ...   Feb 9 2004, 21:30
- - MGuti   if all the samples were problem samples, this woul...   Feb 9 2004, 22:00
- - ChristianHJW   To make this test sensible, you have to remove the...   Feb 9 2004, 22:03
- - Continuum   Some remarks: I think neither MP3 nor Vorbis is a...   Feb 9 2004, 22:08
- - music_man_mpc   QUOTE (Continuum @ Feb 9 2004, 01:08 PM)QUOTE...   Feb 9 2004, 22:19
- - Kalamity   QUOTE (music_man_mpc)We should start making some p...   Feb 10 2004, 00:07
- - music_man_mpc   QUOTE (Kalamity @ Feb 9 2004, 03:07 PM)QUOTE ...   Feb 10 2004, 01:16
- - Kalamity   QUOTE (music_man_mpc)I agree with you in terms of ...   Feb 10 2004, 01:52
- - ScorLibran   QUOTE (Kalamity @ Feb 9 2004, 03:00 AM)Some o...   Feb 10 2004, 02:08
- - music_man_mpc   QUOTE (Kalamity @ Feb 9 2004, 04:52 PM)QUOTE ...   Feb 10 2004, 02:18
- - ScorLibran   QUOTE (Kalamity @ Feb 9 2004, 07:52 PM)I do n...   Feb 10 2004, 02:30
- - Doctor   For narrowing down quality settings use binary sea...   Feb 10 2004, 02:43
- - Kalamity   QUOTE (ScorLibran)QUOTE (Kalamity @ Feb 9 200...   Feb 10 2004, 02:59
- - Vertigo   Do we ask why god is omnipotent? He just is....sa...   Feb 10 2004, 04:00
- - rjamorim   QUOTE (Vertigo @ Feb 10 2004, 01:00 AM)Do we ...   Feb 10 2004, 04:07
- - Dologan   The god part or the MPC part?   Feb 10 2004, 04:22
- - Mr_Rabid_Teddybear   QUOTE (rjamorim @ Feb 9 2004, 07:07 PM)QUOTE ...   Feb 10 2004, 04:33
- - music_man_mpc   QUOTE (Doctor @ Feb 9 2004, 05:43 PM)For narr...   Feb 10 2004, 04:59
- - music_man_mpc   QUOTE (music_man_mpc @ Feb 9 2004, 07:59 PM)E...   Feb 10 2004, 15:43
- - Doctor   QUOTE (music_man_mpc @ Feb 10 2004, 09:43 AM)...   Feb 11 2004, 02:17
- - music_man_mpc   QUOTE (Doctor @ Feb 10 2004, 05:17 PM)Regardi...   Feb 11 2004, 04:53
- - Eli   Wouldnt a problem sample set make the most sense? ...   Feb 11 2004, 04:55
- - music_man_mpc   QUOTE (Eli @ Feb 10 2004, 07:55 PM)Wouldnt a ...   Feb 11 2004, 05:00
- - ScorLibran   Well, the time frame for this test should really b...   Feb 11 2004, 05:24
- - Kalamity   QUOTE (music_man_mpc @ Feb 10 2004, 07:53 PM)...   Feb 11 2004, 06:22
- - SometimesWarrior   Whoa, I haven't posted here in 6 months! I...   Feb 11 2004, 06:41
- - ChangFest   QUOTE Here's my point: if we're testing fo...   Feb 11 2004, 16:18
- - Eli   QUOTE (music_man_mpc @ Feb 10 2004, 11:00 PM)...   Feb 11 2004, 16:57
- - ChangFest   QUOTE However if one codec handles problem samples...   Feb 11 2004, 23:04
- - Eli   QUOTE (ChangFest @ Feb 11 2004, 05:04 PM)QUOT...   Feb 11 2004, 23:16
- - SometimesWarrior   QUOTE (Eli @ Feb 11 2004, 02:16 PM)IMHO a tes...   Feb 12 2004, 00:38
- - Doctor   Hm, I feel a flamefest waiting to happen. Before e...   Feb 12 2004, 00:59
- - Doctor   Concerning the goal of the test. It is obviously i...   Feb 12 2004, 01:10
- - Kalamity   I would not consider this thread flammable, let al...   Feb 12 2004, 05:23
- - 2Bdecided   Before spending hours discussing and thinking abou...   Feb 12 2004, 12:18
- - Continuum   QUOTE (2Bdecided @ Feb 12 2004, 12:18 PM)Cons...   Feb 12 2004, 12:40
- - 2Bdecided   QUOTE (Continuum @ Feb 12 2004, 11:40 AM)QUOT...   Feb 12 2004, 12:51
- - fanerman91   This "Really Big Codec Test" sounds exci...   Apr 18 2004, 04:18
- - ScorLibran   QUOTE (fanerman91 @ Apr 17 2004, 10:18 PM)Thi...   Apr 18 2004, 05:43
- - damiandimitri   QUOTE Consider each negative ABX result as a ...   Apr 19 2004, 12:04
- - tigre   QUOTE (damiandimitri @ Apr 19 2004, 01:04 PM)...   Apr 19 2004, 12:46


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