a response to a growing rumor...
a response to a growing rumor...
Feb 12 2002, 00:36
Joined: 26-August 02
From: Nottingham, UK
Member No.: 1
Normally I wouldn't attempt to address an issue in this manner, but since it is getting a bit out of hand, and usually on boards I'm not participating in (or have little desire to participate in), I'll try and address it officially, once, in the place where it should be the most relevant.
The matter I'm discussing is related to the --alt-presets and their handling of the "stereo image".
There have been some completely unsubstantiated reports and rampant speculation going on in a few threads which I will list below:
3. http://www.hydrogenaudio.org/forums/showth...s=&threadid=759 (I simply hadn't gotten around to responding to this thread though its on this board).
At any rate, I'll try to make a few points as clearly as I can.
1. All of the --alt-preset VBR modes are tuned for "stereo image".
2. All of the vbr presets provide better sound quality via joint stereo than LAME on it's own with joint stereo, and in some cases should even sound better than with --nssafejoint, while at the same time providing a lower bitrate.
3. The --alt-presets do not, by design, make any sacrifice in regards to stereo image to keep bitrate down. Anyone who tells you this has no idea what they are talking about. I should know since I actually wrote the code and designed the presets.
4. An extremely high degree of stereo frames is not always needed to achieve good sound quality. I challenge anyone who believes that --alt-preset standard has poor stereo seperation, on a common basis (as a few unsubstantiated claims imply), to provide me with direct evidence of this.
5. Joint stereo is needed even at bitrates of 320kbps to achieve the best sound quality in some critical cases. Forcing stereo on everything up to 320kbps and then forcing joint stereo does not fix the problem (as user implies in one of those threads). I've tried this before.
6. There seems to be a misconception that all that the --alt-presets improve on are pre-echo. This is sorely mistaken. Indeed they do improve on pre-echo and impulse handling to a fairly large degree, but they also improve upon:
- joint stereo handling (serioustrouble is a prime example)
- dropout prevention (2nd_vent_clip is a prime example)
- fluttering (gekkou is a prime example)
- knocking (velvet is a prime example)
- ringing (bloodline is a prime example)
- noise pumping (piano, rach_original, etc, are examples)
- rasping (present with noise shaping 2 on some clips like fatboy, or on clean vocals sometimes. Mostly eliminated, even on the most critical samples, with --alt-presets)
And that's just the stuff I can think of off the top of my head.
Now, that's not to say the --alt-presets are perfect. I certainly know they aren't. But they also don't have some massive flaw in regards to stereo image which is present to the degree some people imply. In fact, the only case I've seen which I put any credence in is the few isolated cases which Wombat has found (and provided samples for I might add). I will eventually attempt to address these few samples, but note that these are exceptional cases, not common cases, and as far as I can tell, they are completely unrelated to the other complaints being made. This is especially so since Wombat doesn't describe the artifact as being a collapse of the stereo field (which isn't your typical joint stereo artifact in LAME anyway...).
At any rate, I'm always looking to improve things if I can, but claims must be substantiated which includes providing abx results (which are then verified by other parties) and providing test samples, preferrably multiple ones if you are implying a problem with general behavior.
Not to come across arrogant, but for the most part, I'm the only one who truly understands the workings behind the --alt-preset specific tunings. Not even the other developers have followed my work (though that's by their choice, not mine). The code is available for all to see, but so far I have not seen anyone attempt to reimplement my modifications or to discuss them with me on a technical level. So unless you see someone who is closely related to the work I've done (ie, they have participated in testing, JohnV for example) stating something, or you see me stating something directly about the presets, then chances are whoever is discussing the presets doesn't have the full picture. This is especially true when people begin discussing how the --alt-presets work internally or technically, and especially in relation to joint stereo.
If you see a discussion on another board about these issues, please point people to this thread. If you have a question, please ask me here, you'll likely get a much more correct answer in addition to helping to keep questions about this issue centralized and concise (which will help when the FAQs are created). Speculation is not only wasteful, but it also helps to propogate misinformation such as the old "joint stereo is bad" line of thinking.
Feb 13 2002, 23:00
Joined: 15-December 01
Member No.: 662
That is some hard evidence, Dibrom! It may not exactly be on topic but I would like to comment on the "youth hears more hf" statement.
Short version: young folk (rough estimate: up to 14 years) do not have trained hearing. Almost anything sounds good to them. They enjoy the music itself and not it's good or bad reproduction. Many young adults kill their ears in discos. Both do not need hf reproduction so discussion focusing on this group of people is irrelevant.
The question is, how relevant is hf reproduction for "youngsters"? From personal experience I wish to claim that it is not until a certain age that young people will start to actually listen to music. After taking that step it takes a while for them to develop a feeling for what sounds good or bad. After this it takes yet another while until they start to actually demand quality and understand what this means. Very many (young) people still take 128k fastenc quality as transparent and they experience no gain when going any higher. It takes time to get "educated" in terms of listening.
Probably most are listening on relatively low fidelity equipment ( --> flaws in hf reproduction) especially poor PC speakers when it comes to mp3 (ok, so they burn to CD too and listen through their rel. cheap stereo) and wouldn't be able to make out the difference anyway.
Another point is that a whole bunch (of older teenagers and up) visit discos/clubs almost every weekend where their ears get blasted by very high volumes on setups that are tuned by people who themselves have ruined their hearing and compensate for their hf hearing loss by boosting the treble way too much, thus resulting in even faster loss of the hf hearing of the visitors. In 10-20 years we will be facing a large mass of people with damaged hearing. I cringe whenever I enter such a freakin' loud place. (On a side note: more and more people start to wear ear plugs when they go to discos or concerts. How about turning down the volume?)
A small anecdote: on a trance music related forum some DJ said that after spinning for a while he could no longer hear the bass drum in his headphones. It turned out he had the main speakers directly behind him hammering in on his ears at close range. After some discussion about hearing loss and some "Dude! Are you mad?!" and talking about his sucky headphones he decided to go for louder headphones with better bass reproduction... (wonder how he kept the needle from skipping; probably added a lot of weight )
I guess what I'm trying to say (not so sure there myself ) is that this whole discussion about satisfying younger people with hf repro is overhyped. Claiming that a 13 year old will much rather listen to an encode with more high frequencies is simply not true (see long version). Young folk around 20 ruin their ears anyway so they don't care either. You loose more hf hearing capabilty the older you get.
Then there is the group of people who demand high fidelity and have the hearing to enjoy it (not only focused on hf of course). Those are the ones we are trying to please. Not "ignorant" children or half deaf clubbers. Discussion should focus on the needs of people who require high quality! Arguing wether or not a five year old would percieve the hf in some specific encode is just irrelevant.
What I have said is not based on research just on some thinking I've been doing, so please speak up if you know better! (Phew! Longest post I've ever done on this forum )
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