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Hey inmates,
After all these years, I'll finally admit ignorance and just ask. What are the telltale signs of compression? Must be obvious -- it gets pointed out routinely. I don't know what to listen for.
Thanks,
Aram
Follow Ups:
I get it. I think I have one or two or 980 CDs that sound like that. ;)
Aram
If you want to get an idea of the ill effects of compression then listen to Metallica - Death Magnet and/or Rush - Vapor Trails. Both cds are some of the top offenders of compression. BTW, I do not recommend shelling out a dime for either of these abominations (they can be obtained though different channels).
If you go to Youtube and do a search on Death Magnetic - CD vs. Guitar Hero Version, this will give you a first hand comparison of compression.
Also, do a search on loudness wars/dynamic range database. This database has information/rating on the dynamic range of various albums. Check out the ratings for Death Magnet and Vapor Trails! :)
-Ionman
"An ounce of perception, a pound of obscure." - Neil Peart
nt
The simplest and quickest way is to find the loudest part of a track and then adjust the volume control until the volume sounds about "right". Then take a look at the setting of the dial. The comparison will usally be valid across recordings from the same musical genre and the same instrumentation, but won't necessary be valid when comparing different genres or instrumentation. In the case of pop or rock, one needs to compare classic recordings in their original CD mastering with modern mastering of the same or similar recordings. This isn't a strictly reliable method, as the volume setting of two recordings with identical (e.g. no) compression may differ if one was "normalized" to a different peak level. But this method gives a quick 10 second "in your face" indication that something is drastically wrong with a recording. Or, if the volume control appears to be set very low because you had been playing a crappy loud recording it gives you a wake-up call that there may be hope for the new recording.
The best audiophile recordings may require over 20 dB more gain with the volume control than crappy recordings. (Often about 10 clicks with discrete volume controls.) When these recordings are played back with the volume control set too low or on a system that lacks sufficient headroom in the amplifiers and speakers they can sound anemic. Should this happen, it's not the recording's fault, it's the user's fault for not turning up the volume loud enough or not having an adequate system for the scope of music involved. (Some excellent audiophile recordings have gotten a false rap because they were not played back properly.)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
There's more than one way to do things at the production end of things.
Sometimes the whole recording is simply boosted in overall volume and anything over the maximum volume is hard clipped. These CDs can end up very in-your-face and harsh.
There is also a "compander" effect where there isn't necessarily a lot of clipping, but the soft parts are brought up in volume. This reduces they dynamic range. The result is the recording is more listenable as background music or in environments with competing noise (cars, etc.) but when listened to critically, the reduced dynamic range robs the recording of some of its life.
A lot of recordings are multi-tracked at the studio, with a separate channel for each instrument. Some instruments, such as drums, can have multiple tracks of their own. Modern studios make it pretty easy to compress or limit one track and not another, or to apply different amounts to different tracks.
Compression and limiting by a skilled engineer on a per-track basis who isn't being heavy-handed can be hard to spot.
I recall taking a look at a Lucinda Williams track a few years back and noticed the visual display indicated all of the drum strikes were all of absolutely uniform intensity. That's something that was impossible in the old analog days - one would see several dB difference between individual drum hits over the course of the passage.
Such uniformity can sound interesting at first, but it often robs the recording of its "human" qualities. Sometimes "perfect" isn't as musically interesting as "human".
In short, what to listen for depends on how they limited or compressed the recording. And it isn't necessarily bad. Rock 'n roll, for example, depends to some degree on compression. The problem is, in these days of the "loudness wars", that it is easy to go over-the-top and end up with a recording that is harsh and annoying.
I have a question:
Given the enormous dynamic range of actual live performances, the sensitivity of speakers recording microphones, and limitations of actual amplification - wouldn't compression of some kind be a necessary evil?
Isn't it a trade off?
"Knowledge is knowing that a tomato is a fruit. Wisdom is knowing not to put it in a fruit salad"
Today, recording technology can easily handle the dynamic range of uncompressed music. This hasn't been a problem for 50 years. Prior to that musicians made accommodation in their performance to the available technology. Playback technology can reproduce the full dynamic range of a symphony orchestra or other large musical ensemble, and the playback equipment need not be particularly costly unless the room is large (which probably implies an affluent consumer). A system with this capability need not cost more than a few thousand dollars. About the only technical reason for compression today is the desire for the music to be heard in specialized situations, e.g. as background music or in a noisy automobile. This is a pretty poor excuse for dumbing down music, especially since the technology exists today to inexpensively compress music during playback.
The reason for excessive compression is greed and ignorance. If one is marketing music to idiots who are unable to adjust a volume control then perhaps compression is appropriate. The present industry model for some musical genres assumes that the executives deciding on which music succeeds or fails commercially are idiots. But then most of the musicians playing in the hope of getting rich rather than out of love of music are probably idiots and their music probably deserves to be butchered.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
"The reason for excessive compression is greed and ignorance."
I remember the old "Dyna flex" LP's ... awful, awful awful. MP3's sounded better. THink it has a similar root cause.
Agree that music loses something when compressed - but the "thwack" of a drum or some peaks are loud enough that I was wondering if a little compression would be "ok"
"Knowledge is knowing that a tomato is a fruit. Wisdom is knowing not to put it in a fruit salad"
Do you mean "Dynagroove" which was a different process from Dyna Flex? I don't recall any Dyna Flex disks, but the Dynagrooves were horrible. Fortunately I only bought one with my own money.
It's OK to chop off one or two isolated peaks in a track if they are artifacts of multiple waves happening to roll in phase. (There are usually better ways of doing it than straight clipping.) If this is done with skill the result won't be audible and the rest of the track can be boosted. However, if the exact same processing is done repeatedly (e.g. on repeated drum hits) then the changes may be individually inaudible, but taking the track as a whole there will be degradation. It may manifest as a sense of unease or possibly as a conscious feeling that the recording is "unnatural".
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
nt
"Knowledge is knowing that a tomato is a fruit. Wisdom is knowing not to put it in a fruit salad"
> > wouldn't compression of some kind be a necessary evil?
That's another "depends" - who's the artist, what's the genre, what musical instruments, what's the mix of acoustic vs amplified, and so on.
A small acoustic vocal or instrumental group may be fine with no limiting or compression at all. Perhaps even a classical orchestra, depending on the work they're playing and who's in charge of the ultimate sound quality.
However, throw in a drum kit with close miking and you may need some limiting to keep the odd drum strike from overloading things. Move that to a rock group with the lead singer swallowing his mike with a bunch of amplified instruments getting banged, and you'll probably need a lot more compression and limiting to get the "sound" the producer is after.
I don't think many knowledgeable people on the recording side would claim that no compression and no limiting are the only way to record. The problem is that for some outfits, it's simply become a race to see who can make their music the loudest. Unfortunately with CDs, they have a brick wall when it comes to how loud you can make a recording. That means you have to clip severely and compress the daylights out of the music to win that prize.
I've never quite figured out who that impresses and why, but it's sure not the way I like my recordings.
Here is a video that explains it
Afterwards we discovered faith; it's all you need
Note: not "all" re-mastered cd's get this kind of treatment. But a lot sure do.
Hi all ! that video was a perfect example.
It sounds like a wide band width table radio, no excitement to the music. I think of the old Linn tap your feet to the music, except here you have no uge to tap.
You hear a loud puree of sound, with little inner detail...... The textures to the instruments are missing in action..........
In an orchestral track, the crescendos "blast". In a rock track, it's just loud, with no sense of attacks and decays in the drums and cymbals, and no sense of "tone" in the electric guitars. Female vocals tend to sound piercing.
The overall presentation is a "loud wall of sound" rather than "real musicians performing in real space"............
Big difference in Coldplay on CD and LP - the LP has a lot more musical detail, and sounds more natural.
And for me, well recorded digital sounds more "live" than LP, but is most often munged up in a misguided idea to make it sound "good on [x]" (x could be anything from a car to a tinny boombox, or "when ripped to mp3" ... I listen to LP because certain things ... such as Dark Side of the Moon ... or recent pop music just NEED to be played as an LP!)
Oh ... and after this threrad, I turned on the 'ol XM radio and about puked! No wonder I just use it for news and talk radio and feel compelled go to FM for my music when radio listening!!)
"Knowledge is knowing that a tomato is a fruit. Wisdom is knowing not to put it in a fruit salad"
.....bought the vinyl...... (What's funny is it comes with a CD of the album.) And I have to agree..... The tracks are variable, ranging from wretched to very good. The "limiting" is still very apparent, but there is some decent dynamics on the better tracks. And most importantly, the "128 kbps MP3" resolution is totally gone, and the music connected with me so much more than with the CD. The limitations aside, I now say this is a really nice album............
My only other comment is- Thank you very much!!
When people talk about the compression problem or mastering things hot, it primarily means low dynamic range with everything near the max volume (digitally). Most popular music CDs and what you hear on the radio is mastered this way on purpose, because high dynamic range runs the risk of having someone turn up the volume and then getting blasted (imagine that happening while wearing earphones), and also because quiet parts would be totally lost in noisy environments like cars and subways.
But there's also a chance that the audio data was clipped during the sound engineering process, usually as a result of the compression work. If this happens, then you will get additional distortion and messy sound, where the level of distortion will be higher with lower-quality DAC implementations (easily heard in a $30 DVD player's analog outputs, for example).
The high compression used in modern recordings tends to make all the instruments the same loudness, the music never gets quiet or has any natural dynamics. All of the detail and nuance that make music sound natural are now in your face. The bass is more prominent, giving it a punchy sound. You can often hear parts of the music pumping in relation to the vocals as the compressors try to maintain the high average level. It's just fatiguing after awhile, so consider yourself lucky if you aren't bothered by the high compression in modern recordings and masterings.
Compressed music has little depth because all of the musical components/instruments are made the same loudness or lined up in one plain across stereo image. I guess it doesn't matter much if your listing to a heavy metal quartet but for larger groups and more complex music (which has pretty much disappeared anyway) it's nice to hear that "triangle", tympani or other subtle percussive effect coming from the back of the orchestra like it's suppose to. Maybe music started to changed with the "Wall Of Sound" concept from Phil Spector :-)
With compressed music there is the false sense that there is more detail because these previously mentioned subtle distant sounds are made louder but what has been lost is the depth and authentic of the music.
Even when the one describing it intends it to be positive........
I've always perceived it as "blasting" mistaken for "incredible dynamics".
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