iTunes encoding quality

Best overall (quality v. size balanced) bit-rate is ...

  • 128kbps

  • 160kbps

  • 192kbps

  • higher than 192kbps

Results are only viewable after voting.
I agree to some extent...

I'm not an audiophile, and my stuffs (I wouldn't bother listing, unless requested) will prolly be considered mid-fi by real audiophiles...

so, can I hear the difference between CD and mp3?

actually yes, even at 256kbps... but in my opinion, that has more to do with the soundcard of my mac, the output (headphone out...) and the cable connecting mac and my preamp.

so if I'm listening to music, while doing nothing else (or little), I'd always use CD. But if I'm listening to music as some background music while I do other stuffs, I can live with iTunes. The advantage being I can just use a playlist, and don't have to change CD, etc...I can just keep working.

If I play CD or mp3 on my mac, they'd both sound shitty because the builtin speaker ain't worth a damn...

If you determine the quality of mp3 by how much difference from CD you can actually detect, then the equipment you use will have as much to do with the numbers, etc......

but...mp3 encoders are improving.. and ATRAC3 has come a long way, too... I remember the first time I heard MD... it was just shitty. My feeling was "smaller than tape, no-where near CD". I dunno when was the last time you used MD, but it's alot better than that now. I wouldn't mind using it now...as portable media.

in any case... I've always felt it's your ears that must be satisfied... and as I've said, your equipment will affect how you come to your decision. I "recommended" 256kbps stereo (ms if you're using lame), but the real solution probably is just to play around with a few of your favorite tracks...if you can hear the difference, then calculate the change in file size (total) and see if it's worth it... if you can't hear the difference, then why bother.

anyone know what encoder iTunes comes with, btw? I'd definitely encourage you to get lame encoder.

hmm.......I've always imagined it'll be easier to get that kinda stuffs in UK... after all, alot of people go there to hunt for old records... Quad 63...how long have you had that thing? have you listened to the new quads? nobody around here has one... :(
 
Does your 128kbs mp3 let you happy earing them ?
Sound is so related to your earing skill ! I have pretty good earing, compensing my deficient eyes. I noticed that 192 give me back a quite full sound with a 3 or 5 pieces sound system. But most of my friends don't ear the difference between a 128 and a 192.
I encode in 192 to preserve a good quality when a encode my mp3s in AIFF to play them on my hifi. When it's symphonic music, I try to catch 256 mp3. It's better. But it take to much place to do it systematicly.

However, does anyone ever eared the sound of a ATP 700 sound system. For a quarter price to the Harman Kardon, it's so.... waouh !
 
FYI (Fraunhofer is the inventor of mp3 technology along with Thomson RCA)

http://www.iis.fhg.de/amm/techinf/layer3/index.html

===
MPEG Audio Layer-3
History Quality Details

History  

In 1987, the Fraunhofer IIS-A started to work on perceptual audio coding in the framework of the EUREKA project EU147, Digital Audio Broadcasting (DAB). In a joint cooperation with the University of Erlangen (Prof. Dieter Seitzer), the Fraunhofer IIS-A finally devised a very powerful algorithm that is standardized as ISO-MPEG Audio Layer-3 (IS 11172-3 and IS 13818-3).
 
Without data reduction, digital audio signals typically consist of 16 bit samples recorded at a sampling rate more than twice the actual audio bandwidth (e.g. 44.1 kHz for Compact Disks). So you end up with more than 1.400 Mbit to represent just one second of stereo music in CD quality. By using MPEG audio coding, you may shrink down the original sound data from a CD by a factor of 12, without losing sound quality. Factors of 24 and even more still maintain a sound quality that is significantly better than what you get by just reducing the sampling rate and the resolution of your samples. Basically, this is realized by perceptual coding techniques addressing the perception of sound waves by the human ear.
 
Using MPEG audio, one may achieve a typical data reduction of
 
1:4 by Layer 1 (corresponds with 384 kbps for a stereo signal),
1:6...1:8 by Layer 2 (corresponds with 256..192 kbps for a stereo signal),
1:10...1:12 by Layer 3 (corresponds with 128..112 kbps for a stereo signal),
still maintaining the original CD sound quality.
 
By exploiting stereo effects and by limiting the audio bandwidth, the coding schemes may achieve an acceptable sound quality at even lower bitrates. MPEG Layer-3 is the most powerful member of the MPEG audio coding family. For a given sound quality level, it requires the lowest bitrate - or for a given bitrate, it achieves the highest sound quality.
 

Sound Quality  

Some typical performance data of MPEG Layer-3 are:
 
sound quality bandwidth mode bitrate reduction ratio
telephone sound 2.5 kHz mono 8 kbps * 96:1
better than short-wave 4.5 kHz mono 16 kbps 48:1
better than AM radio 7.5 kHz mono 32 kbps 24:1
similar to FM radio 11 kHz stereo 56...64 kbps 26...24:1
near-CD 15 kHz stereo 96 kbps 16:1
CD >15 kHz stereo 112..128kbps 14..12:1
*) Fraunhofer uses a non-ISO extension of MPEG Layer-3 for enhanced performance ("MPEG 2.5")
 

In all international listening tests, MPEG Layer-3 impressively proved its superior performance, maintaining the original sound quality at a data reduction of 1:12 (around 64 kbit/s per audio channel). If applications may tolerate a limited bandwidth of around 10 kHz, a reasonable sound quality for stereo signals can be achieved even at a reduction of 1:24.
 
For the use of low bit-rate audio coding schemes in broadcast applications at bitrates of 60 kbit/s per audio channel, the ITU-R recommends MPEG Layer-3. (ITU-R doc. BS.1115)
 

Details  

Filter bank
 
The filter bank used in MPEG Layer-3 is a hybrid filter bank which consists of a polyphase filter bank and a Modified Discrete Cosine Transform (MDCT). This hybrid form was chosen for reasons of compatibility to its predecessors, Layer-1 and Layer-2.
 
Perceptual Model
 
The perceptual model is mainly determining the quality of a given encoder implementation. It uses either a separate filter bank or combines the calculation of energy values (for the masking calculations) and the main filter bank. The output of the perceptual model consists of values for the masking threshold or the allowed noise for each coder partition. If the quantization noise can be kept below the masking threshold, then the compression results should be indistinguishable from the original signal.
 
Joint Stereo
 
Joint stereo coding takes advantage of the fact that both channels of a stereo channel pair contain far the same information. These stereophonic irrelevancies and redundancies are exploited to reduce the total bitrate. Joint stereo is used in cases where only low bitrates are available but stereo signals are desired.
 
Quantization and Coding
 
A system of two nested iteration loops is the common solution for quantization and coding in a Layer-3 encoder.
 
Quantization is done via a power-law quantizer. In this way, larger values are automatically coded with less accuracy and some noise shaping is already built into the quantization process.
 
The quantized values are coded by Huffman coding. As a specific method for entropy coding, hufman coding is lossless. Thus is called noiseless coding because no noise is added to the audio signal.
 
The process to find the optimum gain and scalefactors for a given block, bit-rate and output from the perceptual model is usually done by two nested iteration loops in an analysis-by-synthesis way:
 

* Inner iteration loop (rate loop)
 
The Huffman code tables assign shorter code words to (more frequent) smaller quantized values. If the number of bits resulting from the coding operation exceeds the number of bits available to code a given block of data, this can be corrected by adjusting the global gain to result in a larger quantization step size, leading to smaller quantized values. This operation is repeated with different quantization step sizes until the resulting bit demand for Huffman coding is small enough. The loop is called rate loop because it modifies the overall coder rate until it is small enough.

* Outer iteration loop (noise control/distortion loop)
 
To shape the quantization noise according to the masking threshold, scalefactors are applied to each scalefactor band. The systems starts with a default factor of 1.0 for each band. If the quantization noise in a given band is found to exceed the masking threshold (allowed noise) as supplied by the perceptual model, the scalefactor for this band is adjusted to reduce the quantization noise. Since achieving a smaller quantization noise requires a larger number of quantization steps and thus a higher bitrate, the rate adjustment loop has to be repeated every time new scalefactors are used. In other words, the rate loop is nested within the noise control loop. The outer (noise control) loop is executed until the actual noise (computed from the difference of the original spectral values minus the quantized spectral values) is below the masking threshold for every scalefactor band (i.e. critical band). 
 
There will be a difference in sound quality between one bit rate vs another ... and between mp3 and CD. MP3 is a lossy compression in which some of the data is always thrown out in the interest of file size. Researchers are becoming more clever about *which* data can be tossed out while keeping the *perceived* sound quality relatively high.
It's rather irksome that the marketing droids affix the label "CD quaility" to mp3 devices/software when technically, it's not true. CD "quality" is 16 bit, 44.1khz! :(

I've done some experiments and have found 160k about the lowest bit rate I can stand to listen to music with. Anything lower there's too many compression artifacts. As a rule, if the CD sounds kinda crummy to begin with, I'll encode at 160, if it's a medium quality recording I'll select 192, and if it's a jazz or classical recording of high quality I'll choose 256 or higher. I find these settings sound fine on my G3 with Boston Acoustics sat/sub 3-piece speakers that I use at work.

I also have an audio system at home comparable to some of the previous posters and I can say without a doubt that mp3 encoded audio sounds nothing like the original CD. Depending on the music you can get acceptable results (comparable to the sound of FM radio I'd say) but nothing real great. This may change in the future with more sophisticated compression algorithms that (hopefully) don't throw out any data. If anyone cares (probably not, but I'll say it anyways ;) ) LP records still sound better than CD's.

Bottom line? Go with what your ears tell you and don't worry about it. :)
 
"If anyone cares (probably not, but I'll say it anyways ) LP records still sound better than CD's. "

I couldn't agree with you more!
 
Originally posted by 2001pass-var
"If anyone cares (probably not, but I'll say it anyways ) LP records still sound better than CD's. "

I couldn't agree with you more!
Click to expand...

and tubes are better!
 
Originally posted by beef


and tubes are better!
Click to expand...

Yes, vacuum tubes DO rock. :)


Ok folks, so it looks like I'm going to re-encode ALL my CD's (that's a lot) at 192k (or 224k). Wadda ya think?
 
Beef - re your comments about the EL63's - I have heard the new Quads and I don't think they are as good. Perhaps I'd get used to them if I had them at home for long enough ...

I'm not certain but I think that Quad continues to make the EL63 - mine aren't that old.

Hardcore HiFi fans prefer the original Quad electrostatics!

Couldn't agree more about valves (as we quaint oldworlders call them!)
 
Originally posted by Myke
Beef - re your comments about the EL63's - I have heard the new Quads and I don't think they are as good. Perhaps I'd get used to them if I had them at home for long enough ...

I'm not certain but I think that Quad continues to make the EL63 - mine aren't that old.

Hardcore HiFi fans prefer the original Quad electrostatics!

Couldn't agree more about valves (as we quaint oldworlders call them!)
Click to expand...

hmm... interesting... I knew there were shops that does repair, etc, for the original EL63's... but I wasn't aware that Quad still made those...

I guess I'd give Santa a call

and... yea... I have to agree... unless you can audition things at your own home for awhile... it's really hard to see how things fit in...
 
Tubes don't actually sound better, they have more resonance, and if you prefer more resonance in your music, you're going to enjoy tubes more. It's subjective.
 
I'm not sure what Jadey means by "resonance" - but I think it's a little more complex than that!

All the same it is true there's no 'right' answer in HiFi. The distortions involved in the recording process - such as the aural signature of microphones, the ambience of the recording environment, the 'mix' and so on - mean that you never get to hear the original sound.

But - so what? Good HiFi is still a joy to listen to.

By the way, Beef, I think you may be confusing the EL63's, which came out in the 80's, with the original Quad speakers which were made in the 60's.

The EL63's were definately on sale a couple of years ago when I last looked, alongside Quad's latest speakers, the name/number of which escape me.

Incidentally, can anyone explain why my G4/733 has an analogue audio output, but no input? I find the output pretty good, apart from a low level hum problem (I mean very low level)

However, using a music card like Protools Digi001 puts the Mac up there with the most expensive of HIFI.
 
I'm definitely an audiophile, and I've had my Mac hooked up to my surround sound system since day 1 ... and something I noticed that iTunes does that I haven't seen with other encoders is that it keeps the surround channel in audio CDs. I was floored when I put on the Tool MP3s I had made from a friend's copy of Lateralus (I know I know I need to buy it but I'm broke) and heard distinctly the surround channel. These were encoded at 160, and sounded great.

I re-encoded them at 192 a little while later, bumped the file size up considerably, but I didn't get that much better quality out of it. Some of the toms stilll sounded weak to me, and the guitar/bass still bled together a little bit. But overall, it sounded just dandy, better than tape quality at any rate, and isn't that what MP3s are here to replace more than anything?

My vote is 160, especially if you are limited in HD space. I'm struggling with my 12GB drive ... i have X, 9 Classic, and 9 Main systems installed, plus all the apps?!?! And VPC with a full install of Win2K?!?! I don't have that much left to worry about the marginal difference in quality between 160 and 192.
 
uh... isn't Tool Lateralus in STEREO?

if you select surround sound mode in your preamp, anything will come out in 5.1, 7.1, or whatever it supports... but the surrond channels won't have their own discrete sound... if the surround channels seem to have their own sound... i think that has more to do with the difference between your main and surround speaker, and other setup,etc...

but...I'm not an audiophile...and you say you're... so you probably know things I don't... I'm not even sure about Tool's Lateralus encoded 2 channels only... and I own the damn thing (just never bothered to listen in surround...) I'm more of a caveman when it comes to surround music...

...I've listend to some SACD, DVDA, etc... personally, I don't get this surround music... I appreciate surround sound in Movies, etc... but I've never been to a place where I'm actually surrounded by the band. Whatever concert, etc, I've been to, the band is always in front of me... I dunno about you guys, but it'll be a while before I'll get into surround music thing... I'm not gonna listen to Stereo materials in surround either... unless somebody here tells me how it's done right.

well...I've heard a lot of arguments when it comes to tube vs transistor... and I still use Musical Fidelity A3 (pre/amp) which I still think sound good... and transistors tend to have better numbers on test bench...and they produce less tonal harmonic distortions... but afaik, that distortion is high-order/odd-order...while the tubes produce (yea.....a lot more substantial...but...what's the word...soft?) even-order harmonic distortions... which one's more natural...which one never appears in music...?

I probably am biased after reading stuffs... but yea... things come down to personal preferences... after listening to tube and transistor for awhile... I thought I preferred tubes (was I determined to believe tube sounded better...? maybe... I dunno... I was proud of my stuffs, too though...). I prefer stereo for music... etc...

...so yea... whatever you prefer...

and about mp3... I still say encode with LAME (takes a lot of time though) at 192 or better... there're links to lame's latest build and script that works with iTunes at macosx.com.
--edited
I recommended 192 or better, because I think gadgetlover mentioned he has
Creative Jukebox thing. I dunno how long he listens to music, but I personally think the battery would run out before he's done listening to everything in it... and I'm hoping he doesn't mind adding/deleting files in it occasionally.
 
The names of the encoding rate carry meaning: at 128 kbps, mp3 files take up, unsurprisingly, 128 kilobits per second of audio.

128 kb/s / 8 b/B * 60 s/min = 960 KB/min
192 kb/s / 8 b/B * 60 2/min = 1440 KB/min = 1.4 MB/min

And so on.
 
Tubes are better for listening to vintage music because:

1) The guys in the 60's were using tube amps in studios. They recorded, and listened using tube amps, so the music is almost made to be heard through tube amps.

2) Tubes are not flat-frequency. Tubes have a semi-variable compression based on frequency and volume (where as a digital compression algorithm pretty much ignores frequency - and I'm not talking about data compression, just audio compression). This compression yields a fatter warmer sound.

3) Tubes tollerate. You can easily blow out your friend's solid-state class ab amp in his boom box. No prob. But tubes can take abuse.

4) Nuclear-blast resistance. In the event of an EMP from a nuke, most anything that relies on silicon as an electrical semiconductor will become useless. So if we get nuked, I'm gona crank up the music.. because I can!

In my studio, I use a rather large mixer and some Crown, Peavey, and Mackie amps. These amps have a much higher headroom than most home stereo gear, so you don't get any compression or loss of signal dynamics.

When I want to hear my music, though, I use some custom class-a audio amps I built a while back. These use 12 6L6 tubes in class A configuration, and I use one of these amps for each of four channels (which I usually just run in stereo configuration).

Do I use LP's? You bet! Well, untill those movers bonked my lp player... time to get another one I suppose.

I don't compress most of my music. Why? Well, if you have a 60gig hard disk, and are willing to set aside 20 gigs for music, thats... 650mb/disk... about 1gig for two disks... thats forty cds. Which accounts for 90% of the music I listen to. As a rule, I never compress Pink Floyd, Hendrix, or Classical/jazz music.

Seriously, if you enjoy listening to music, go with what sounds best. I don't bother with gold connectors because I used my ossiliscope and a frequency alanizer, and I couldn't see any differnece between gold plated connectors and normal connectors... I do use balanced signal lines whenever possable, though.
 
Originally posted by thedbp
My vote is 160, especially if you are limited in HD space. I'm struggling with my 12GB drive ... i have X, 9 Classic, and 9 Main systems installed, plus all the apps?!?! And VPC with a full install of Win2K?!?! I don't have that much left to worry about the marginal difference in quality between 160 and 192.
Click to expand...
same here, except i've got 2gigs less and softwindows with win98
 
My recommendation for the re-encoding option is to only bother when/if you hear a track or album that you notice any issues with. If you're listening to your stereo passively I doubt you will have any problem with your current 128 quality. If you pop the headphones on or listen more carefully you will notice more aliasing.

I encoded all my CDs based on how much I liked the album. My favorite albums got the 192, most everything else got the 128 and the rarely listened to ones got the low end.

Audiophiles will be audiophiles, but anything beyond 192 for general listening is pointless. I've got a pretty nice set of critical listening monitors (Alesis Monitor Ones) and the 192s sounds excellent. If I need quality beyond that, I'll put the original damn CD in.
 
I encode my mp3's with stereo 160 VBR, quality high and standard stereo.

I have it all hooked up to my HiFi, a Cyrus dAD3 cd-player ($1400), Cyrus Straight Line amplifier ($670) and a Cyrus Power preamp ($800). All hooked up to my speaker's two System audio 1070 ($970).

...I LOVE my system.
 
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