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[Martin_1962]

I have listened to a lot of formats - haven't listened to DAB but their bit rates are lower then radio channels on Freeview - and you can hear the compression on that.

I am not a fan of audio compression - it screws up music - I think that if you must compress ATRAC is pretty good. Movie soundtracks with their industry compression can still sound good though

I have only MOR equipment and I would rate audio quality as such (as I have heard)

I am trying to compare compressed surround as well
DVD-A
SACD
Vinyl
DVD PCM stereo
Beta HiFi
CD
Mini DV audio
DTS and AC3 done really well*
MD and very good cassette
NICAM 728 done properly
DTS normal*
Dolby Digital normal*
FM done properly
DVB-T good bit rates
MP3 done well, ATRAC at LP modes
DVB-T poor bit rates
Poor FM (like today)
AM
Beta linear
Amstrad CD player
Poor cassette
MP3 bottom

* However with a film this is above any stereo format as the compression does not matter as much but multiple speakers do

# I am afraid I have not heard DAT live, and MP3 compression to me grates. My DVD player can play 8 of the above!!!!

@ I still do not understand why MD never took off!

~ My hearing is only average but I cannot easily listen to poor equipment, but I like a wide dynamic range, a wide frequency range flat response and little hiss.

I find CD can grate at high frequencies which is not there on records

[Kevin Wood]

I like a wide dynamic range

That's the killer. MaxV6 will come along with the wisdom on this I'm sure but it seems to me that music is now produced to be a background distraction rather than something to sit down and listen to seriously. The result is that it's compressed into about 10db of dynamic range so you don't miss bits if you're not giving it 100% of your attention. This applies to all radio and tv broadcasts but also to a lot of CDs I've bought, including remasters of stuff that was originally produced extremely well from analogue recordings.

I must admit if I'm not listening seriously I love MP3 for its' convenience. I have a squeezebox and a server full of all my CDs ripped at a decent bit rate and it's great for casually hopping between tracks but I do worry that once CDs are gone the norm will be to buy music in 128kbit MP3 like quality - not that I'd buy it. It's worthless.

Kevin

[Martin_1962]

One of the biggest stresses for audio formats is Heavy Rock, this is a complex and layered music with lots of frequencies used, I have heard CDs go mushy at high frequencies.

On my system DVD-A is just ahead of SACD but I only have two, one of them is a Doors album and it has the low noise floor of CD, the clean highs of Vinyl and sounds better than either. This is PCM with more bits and higher sampling frequency than CD

SACD uses DSD whatever that is

Note that good analogue formats still hold up well

[AndersH]

Can you get a DAB car stereo with a line in jack or usb on the front?

My one has an aux input, a Sony CDX-DAB6650.

I have no reception problems at all in my car, no worse than FM. The reason I have it is I just don't really like any of the FM stations around me and I can listen to 6 music and xfm, there's just a lot more choice and no tuning involved. It's also nice to listen to 5 live in decent quality - no matter how much it's compressed it is still better than any MW reception I can get!

[Bo Bo]

If you can select the display to show signal strength

Well yesterday I had hardly any signal & today it's excellent, no bubbling at all  :-/

[MaxV6]

I have listened to a lot of formats - haven't listened to DAB but their bit rates are lower then radio channels on Freeview - and you can hear the compression on that.

I am not a fan of audio compression - it screws up music - I think that if you must compress ATRAC is pretty good. Movie soundtracks with their industry compression can still sound good though

First of all, we need to distinguish between the different kinds of Compression involved.

Although the word compression is used, it is NOT always the same thing..

consider it like this.
4 types of compression and a rough guide definition

1) Analogue or Digital Compression of the dynamic range of the source material.
This Can be broken further into.....
 A)Dynamic control in the mix process, both as a creative tool, and a corrective tool.
and
B)Dynamic control of the overall product (Mastering)

A) has always been a feature of rock n' roll recordings...  less so with classical, but occasionally to be found almost anywhere...  it's primarily used to give a more consistent level range for a particular source...  to compensate, for example, for the sax player moving around in relation to a static Mic position, too much during an otherwise artistically perfect take....  or to get that fat throbbing, or "pumping" bass sound from a bass and amp that aren't naturally capable of it...

B) Mastering...  Can of worms.....  Big style...  Mastering styles have changed over the years, largely driven by idiot label staff,  or ignorant artiste's desire for their record to be louder than a.n.other band's record.  
In the "good old days" of vinyl being the dominant delivery medium, this was less prevalent due to the physical limitations of the medium....  you could only get "so" loud before the needle jumped out of the track... (note in case i forget later... CD et al actually have LARGER dynamic range than even the best vinyl.. for precisely this reason...  ) but as people moved away form vinyl to digital meia, the trend became endemic...  I'll dig out some links later as there are websites dealing solely with this issue....   looking at waveform graphs of typical albums from different eras gives a instant clue.....   and it was not well appreciated how the limits of digital imposed themselves by anyone other than the white coat wearing geek engineers (....  who are always largely ignored by those in control, then blamed by these same morons for the horrid sounds that result.)  this is still the case, although some people are beginning to learn and appreciate dynamic range more...   largely educated by Audio engineering based  magazines such as "Sound on Sound" , and as these people climb the ranks, maybe some order will be restored...


2) Analogue or Digital compression of the dynamic range of the delivery medium itself.

I already mentioned that Vinyl had physical limitations on it's dynamic range, what i haven't covered are the spectral limits of that medium... it is inherently less well able to convey a large dynamic range low frequency information because of the same reason, The groove size and limits of the needle's ability to stay in that groove...  and also the High frequency roll off of performance, influenced by the mass of the needle assembly, and rotational velocity of the medium.... CD actually has both a wider dynamic range, AND a wider useable frequency response range.  NO vinyl playback medium can approach 20+KHz.
This limitation is coincidentally mirrored in some digital media...  as part of the data compression system, which i'll come to later.
Analogue Tape also has limits, set by the ability of the medium to be coherently encoded and replayed, and the point at which total saturation of the magnetic elements is approached...  and the non-linearity of that system as it does so...  indeed,this is nowadays often used asa creative effect, tracking drums or bass to tape , good and hot, to get magnetic tape saturation distortion as a desired result, which is then played back into digital media for later use...
Digital Limits on dynamic range are set purely by  the media's data storage design, and in traditional PCM systems,that means  the bit depth. 16 bit audio has a maximum theoretical range of about 96dB irrespective of the frequency range or any other issues.. this is an absolute limit... and for this reason, Digital audio is metered and described with relation , not to some arbitrary reference level, as in analogue audio, but to the maximum signal level, (0dBFS , = 0db headroom to digital full scale ) there is NO room to go over this whatsoever... unlike in tape, where things would "warm up" as the harmonic distortion increased approaching full saturation...  in digital once you exceed 0dBFS, you get nothing but white noise .
24 Bit systems do not raise that limit, they work at the other end of the scale, lowering the noise floor , increasing the dynamic range by allowing quieter sounds to be recorded....  and reproduced effectively.....  also beneficial in processing....   anyhow, that gives us a maximum Dynamic range (in theory) of 144dB.
remember that dB is NOT a linear scale but logarithmic...  which in plain english means... the difference in dynamic ranges between 16 bit and 24 bit, is not the 50% or so implied by the headline numbers, but in actuality a linear factor of 10's of thousands .
useful explanations
http://www.sfu.ca/sonic-studio/handbook/Decibel.html
http://www.sss-mag.com/db.html
http://www.jimprice.com/prosound/db.htm

I'll have to come back and finish this later......  I have things I must do now.,...

[Bo Bo]

Blimey Max, War & Peace wasn't long or confusing  
Now where's that copy of Ulysses  

[Dave-C]

We went to Apollo 2000 and Currys to have a look for one for my mum, we wanted to hear the sound quality.  Guess what? Because we were efectively in a bloody big tin shed, there is no signal!  What's that about then..  To digress, I was talking to an ariel rigger on my travels, this is the guys who do the big stuff, 200 ft plus towers.  He sayeth, when they start to turn off the analogue television signal, that they will turn up the digi signals, as currently they are potentially interfering with the analogue signals....  What a load of ******s,

DC

[MaxV6]

Blimey Max, War & Peace wasn't long or confusing  
Now where's that copy of Ulysses  

I'm just getting started...

here begins part 2

okay Compression type No's 3&4. they are related but not identical

3=DATA compression of source material.
This is an ENTIRELY different process to Dynamic compression.
If desired, Data compression can actuallyhave  little or no effect on the dynamic range of the original source material.
What this is about, is reducing the amount of raw data the encoded reproduction has to deliver....
Now there are some very basic , fairly obvious ways to do this, and there are some less obvious, less harmful ways to do this.

Basic ways .
Bandwidth limitation.    Simple, Instead of providing 20Hz to 20KHz as on the CD, simply chop off the bottom 80Hz and top 5KHz.  an instant reduction of easily 30% of all data. the file size would now be 3.5MB per mono track minute , as opposed to 5MB per mono track minute.

Next step in the obvious  and brutal  options would be reduction of bit depth...  which DOES have an effect on AVAILABLE dynamic range...  but it's not always an obvious one...   if the material actually only uses the top 12 bits , then you can cut another 25% off the data size by dropping the bit resolution to 12 bit instead of 16....  but you need to do it with a process that involves noise shaping / dither of the lower scale ends to ameliorate the effects of  a horrid harmonic distortion that would result from simple truncation.
so our file size is now down to  2.6 MB per mono track minute... ....  roughly half the original.

Beyond these two primitive steps lie the realms of the tricky and clever buggers....   Psycho-acoustics and the behaviour of the human mind and ear in listening....   these clever buggers allow us to increase the effective data compression by a factor of ten..... extensions of what i've already covered, and application of techniques a bit like post-scripting
Look up Fraunhoffer if you wish to know more...


4= Audio AND DATA Compression of Broadcast Delivery Media.
Now you MIGHT think that this is the same as above... but you'd be wrong... why??

Well you can deliver the music to broadcast  in any from from SACD down to a cruddy low bit rate MP3...... what the broadcast system does to it afterwards is not related to the original media.

I have to go again.....    more anon...

[Bo Bo]

Blimey Max, War & Peace wasn't long or confusing  
Now where's that copy of Ulysses  

I'm just getting started...

more anon...

[Paul M]

I haven't (yet) read it all bt I'm finding myself in agreement with much of what Max says. I've heard a lot of people say that vinyl gives better sound than CD, but the reality is that it's not (usually) a better reproduction, rather the distortion that vinyl inevitably introduces due to physical limitations produces a more "warm" sound that some people prefer. Nonetheless it's still a distortion that wasn't present at the recording source. That said many CDs are over-produced so similarly deliberate distortions have been introduced -- not a limitation of the media but still a PITA.

Personally I generally avoid MP3 like the plague, it definitely introduces noticeable noise when listening on decent hi-fi equipment. I do have high-bitrate MP3s in the car because my head unit has a built in HD for storing them so it's far easier than having loads of CDs, however the car is a noisy environment with relatively poor speakers (factory fitted) so it's no big deal here. I store all my music in FLAC format and use a script to transcode to MP3 as necessary, including automatic conversion of tags etc.

For those of you who don't know about FLAC, it's a lossless compression so it retains 100% of the original music information while compressing to around half the original size, depending on the complexity of the music. A bit like Zip files for music. You also get the flexible tagging format of Vorbis -- much better than ID3. The beauty of lossless is that you can easily transcode to either another lossless format without losing any quality, or to a lossy format losing only the quality of that lossy format. It's totally open source and has a fair amount of support (Winamp has a plugin, Amarok plays it with Xine, hardware players like the squeezebox play it and even the iPod has a hacked firmware that supports it). http://flac.sourceforge.net/

[MaxV6]

ready for more?

Okay, broadcast delivery systems.

These days, even the analogue service is heavily heavily compressed  AUDIO wise.. even before bandwidth limiting is applied..  

an evil thing called opti-mod..

basically a technique called multi band compression is applied HEAVILY, the louder a station controller wants their output to sound (in relative terms) the more it is poured on..
Multi-band compression arguably allows you to reduce the dynamic range to a greater extent than normal full spectrum compression,  with fewer obvious artefacts spoiling the end result. it does this by dividing up the frequency spectrum, and then compressing each band of the spectrum separately, with optimised compression settings and limiting the output level, before recombining them to give one much louder sounding , heavily controlled, and brick-wall limited end result.
that is then fed to the broadcast delivery system....

In the case of Digital and online systems, various further processes happen dependent on the end use to then shove this homogenised mush down the relevant pipeline...
it's partly these processes, that go some way to accounting for delay times in various broadcast mediums....  that and transmission route...  (to a satellite and back takes longer than going direct....  by wire or broadcast.   you can hear the difference yourselves by tuning in to the same program on Sky Satellite, NTL cable, DAB and Analogue FM , and hearing the different delay times... the Lag to DAB from analogue is about the conversion from analogue to digital, and the processing to squeeze the bandwidth, all of which done at broadcast source... the lags from analogue  to Sky and NTL, are about transmission routes AND processing.

going back for a minute to the data compression techniques... there' an important one i missed out... Stereo field width.

listen to any of the broadcast mediums and then immediately to a CD  ( NOT an MP3) , and one of the most immediate things you'll notice is the increased sense of space and depth the CD has....  this is because it's Stereo imaging is as the creators intended it to be, not squashed down to a pale shadow of itself.. by part mixing the Left and right channels together, reducing the differences between them, so the image appears smaller and less well defined.

the Compressed reproduction delivery media like MP3 and ATRAC (MD)  do this to some extent also....   it's linked in to that whole psycho-acoutics thing..


Right..  

Confused yet?

Basically what this boils down to saying is that There are things you can lay at the door of a delivery broadcast method, and things that are to do with the original recording and mastering at source, and things that are to do with the playback media....  all these things contribute to the end result, and to be able to conclude that A is better than B , you really need to know whether they are actually both equally valid  letters in the first place...   and appreciate the different approaches to emphasis that typing in Bold, or underlining have... and whether they're comparable, or actually Apples Vs Oranges.

To go back to Martin's List..

DVD-A
SACD
Vinyl
DVD PCM stereo
Beta HiFi
CD
Mini DV audio
DTS and AC3 done really well*
MD and very good cassette
NICAM 728 done properly
DTS normal*
Dolby Digital normal*
FM done properly
DVB-T good bit rates
MP3 done well, ATRAC at LP modes
DVB-T poor bit rates
Poor FM (like today)
AM
Beta linear
Amstrad CD player
Poor cassette
MP3 bottom

This really needs to be split up

there are mixed distribution media types AND broadcast types , as well as analogue and digital media types... which as we've seen, even in the limited overview  so far...  have different issues. So, in one sense,  we're comparing Apples to Citrus fruit and Bananas

Not only that but we have a mix of pure audio and Video+audio formats....

In addition to all this...  the majority of people will not have  the means to listen critically to all these formats through the same replay system.,
or indeed, a "decent" replay system at all...

a moment's explanation..
Digital audio replay  largely relies on two things for a decent, accurate sound, leaving aside for a moment the question of amps and speakers... and room acoustics..

1) Clock accuracy.
2) Quality AD & DA converters..referenced to 1.

Essentially what this is about is the ability for the listener's replay system to reproduce the best out of what data it is actually given in the first place..
Clock??  why??

Well, the majority of systems rely on playing back recorded samples of audio both in the same order, AND importantly at the same regular time intervals as the encoding requires....

the consistent accuracy of the clock signal determining playback timing is essential for a good performance, it relates to phase and frequency information inherently... ... and these determine the solidity and depth of the stereo field image

AND  good quality digital to Analogue (DA) converters supported by good quality analogue audio output circuits...  

these things come to several hundred pounds or more..  ON THEIR OWN..

a £47 DVD player, covering 8 formats...   is NEVER going to approach a sound quality "level" of even what the media it's playing is capable of, never mind the source material prior to distribution.,..
Frankly very few playback devices on the market for the consumer have any of the above...  and no two bits of such consumer hardware sound exactly alike either......

and as for those god-awful Set top boxes from NTL, Sky and others, ....  YEUCCHH

Earlier "harsh" sounding complaints about CD were usually a combination of piss poor conversion, piss poor clocks, and pretty shoody reconstruction filter design....  
CD quality Audio only really came in to it's own in the mid to late 90's.. sadly this coincides with the rapid advancement of the loudness wars arms race..

More Anon... this IS the simple version !

[MaxV6]

I haven't (yet) read it all bt I'm finding myself in agreement with much of what Max says. I've heard a lot of people say that vinyl gives better sound than CD, but the reality is that it's not (usually) a better reproduction, rather the distortion that vinyl inevitably introduces due to physical limitations produces a more "warm" sound that some people prefer. Nonetheless it's still a distortion that wasn't present at the recording source. That said many CDs are over-produced so similarly deliberate distortions have been introduced -- not a limitation of the media but still a PITA.

Personally I generally avoid MP3 like the plague, it definitely introduces noticeable noise when listening on decent hi-fi equipment. I do have high-bitrate MP3s in the car because my head unit has a built in HD for storing them so it's far easier than having loads of CDs, however the car is a noisy environment with relatively poor speakers (factory fitted) so it's no big deal here. I store all my music in FLAC format and use a script to transcode to MP3 as necessary, including automatic conversion of tags etc.

For those of you who don't know about FLAC, it's a lossless compression so it retains 100% of the original music information while compressing to around half the original size, depending on the complexity of the music. A bit like Zip files for music. You also get the flexible tagging format of Vorbis -- much better than ID3. The beauty of lossless is that you can easily transcode to either another lossless format without losing any quality, or to a lossy format losing only the quality of that lossy format. It's totally open source and has a fair amount of support (Winamp has a plugin, Amarok plays it with Xine, hardware players like the squeezebox play it and even the iPod has a hacked firmware that supports it). http://flac.sourceforge.net/

There are a few "lossless" compression formats....   some of them even work tolerably well


With regards to "over produced"
this has bugger all to do with the delivery media... there were massively over produced albums made LONG before CD was invented... (See ELP, YES, Supertramp and prog-anything in general for a mere glimpse )

Production is about part of the creative process in writing and recording and mixing the artistic content, NOT about technical delivery of it...

As it happens , a massive jump in the abilities of the studio, available track counts, and the beginnings of MIDI and digital editing coincided with the arrival of the CD medium... so production values were all over the shop during the Media's infancy...

so it mistakenly gets blamed for something it had nothing to do with.,...

Example...   Why would the invention of CD, a delivery media, influence  a certain band choose to add several horn sections, layered synthesisers ,  and a choir of children to a track

answer : not related.... other than happening in the late 70's /early 80's

 
for the record , if i MUST have a data compression format to use, I choose Apple's implementation of MPEG layer4 as used with the iPod.,

it sounds significantly better for any given bit rate than an MP3 of the same bit rate. No matter which MP3 encoder you use.

I'm not extolling the virtues of the iPod, I hate the damn things...   But, they DO sound undeniably better than the competition (thanks not to the hardware but the Encoding of the compressed audio) , and given that Mac use is a fact of life as far as i'm concerned, ( for work and at home, although i DO own PC's as well... )  they do rather have a fully integrated user experience....


If I get time tomorrow, i'll start talking about the various formats and their relative audio quality, and strengths or weaknesses.

someone might want to implement a longer character count limit....  6000 is a bit small

[Martin_1962]

When I bought a portable what it came down to was

1) I have a lot of MDs

2) Price

3) My sort of use

Now I have to swap out if I want more than 1GB but TBH I don't really care. If I wanted I can fit an uncompressed CD on a HiMD.

As to play back - the DVD player I bought was noted as being good at what it does, it is a Pioneer DV575.

A bargain for £110 in a sale, my first player was £500 and I wore it out.

My setup is biased towards multi channel but I do use HiFi speakers except for the centre which is the same brands centre. Castle

The receiver was one of the better mid priced ones when released and still fetches more than its successors on Ebay - Sony STR-DB930.

Now this is not expensive kit but works quite well, it also handles multi channel audio very well as it is not sub/sat.

I know it is a moderately good DVD-A player, an average SACD player and a quite good CD player. It also does well as a DVD player and also does mp3s and MPEG4.

Now my equipment is modest by audiophile standards but is a hell of a lot better than basic music systems and base HiFi components. DVD players can be good audio playback devices, and mid range AV receivers can be made to work well.

The DVD player was a high point one, same as receiver. But I can tell the AV receiver is not as good as it could be - but then I would be looking at around £1000 - which I do not have!

MaxV6 - your posts have been very interesting, and yes a lot of modern CDs are terribly produced.

My local FM station sounds like it is playing low bit rate mp3s sometimes, so I tend to play CDs on the way home but have TA set.

I don't know what it is but a lot of music tends to sound squelchy, I think this is over compression.

Back to TV audio, NICAM 728 was a high point, a very good sounding compressed audio format BBC invented as well!!!! The replacement mpeg2 sound can be very murky, it is OK but is lifeless in comparison - unless high bit rates are used, like 256 or up, some stations are down to 192, some 128, but they should all be aiming for 384.

BTW mp3 is more efficient than MPEG2 audio.

As usual BBC use better rates than other broadcasters.

I have confirmed this my VCR is NICAM converted (yes I fitted an external decoder and modified the VCR) and my PVR has a TOSLink digital out.

I could chat about this all day but I need to get some work done!

[Martin_1962]

There are a few "lossless" compression formats....   some of them even work tolerably well

MDLP?

for the record , if i MUST have a data compression format to use, I choose Apple's implementation of MPEG layer4 as used with the iPod.,

it sounds significantly better for any given bit rate than an MP3 of the same bit rate. No matter which MP3 encoder you use.

I'm not extolling the virtues of the iPod, I hate the damn things...   But, they DO sound undeniably better than the competition (thanks not to the hardware but the Encoding of the compressed audio) , and given that Mac use is a fact of life as far as i'm concerned, ( for work and at home, although i DO own PC's as well... )  they do rather have a fully integrated user experience....

Have you compared with the newer Sony players - basicaly HD5 and newer?

If I get time tomorrow, i'll start talking about the various formats and their relative audio quality, and strengths or weaknesses.

We will be waiting, and will you mention the PCMF1?