Hmm, the problem I think is that in this thread lots of new folks appear, and some start to claim something which is not very well justified at all.

Garf tried to bring some "order to the house". I suggest you first check a bit the forums and get to know the procedures which are used here.

Also you may notice that very knowledgeable people (codec developers etc.) post here, and there are very knowledgeable people in these forums (this may sound elitist) who are closely contacted to the development and testing of the codecs covered in HA or who have many years of expertise about audio coding or audio in general. Now suddenly in the last couple of days there's been lots of new people posting (which is just fine), but the old-timers want the same kind of proofs and procedures from everybody.

Here you can't just claim wild things without proper proofs. You have to be ready to prove your not so well defined claims, and if you don't quite know what you are talking about (and you have only heard something from somewhere), try not to present your issues as a fact...rather ask if it is so. This will help.

JohnV:

It was never my intent to post my experience as facts. Only as an experience. Neither did I know which level this forum held. I had no clue that there is codec developers writing here.

But now I know. Hopefully I will be able to get some usefull answers here from people who know how the CD-ROM player really works in comparison to ordinary cd players.

Q 1: How does the computer/codec know it's getting the exact information from the CD-ROM player? Is there a kind of checksum or other way?

Q 2: Is it possible to make an exact copy of a track reading the CD in 40X speed?

Q 3: Is there a way to burn this exact copy in an exact way to a CD-R disc?

Yes. There are checksums in every sector of an Audio CD that can be tested for correctness of the audio data that has been read.
(the difference between the checksums used in Data CDs and the checksums used in Audio CDs are that Data CDs have some error recovery capabilities, where Audio CDs have only error detection checksums - correct me if I'm wrong, of course)

That said, the codec doesn't do the job of verifying this. The Audio Extraction software does (i.e. the "ripper"). That's why it's important you use Exact Audio Copy or CDex with cdParanoia mode, which both happen to be freeware but both offer superb quality, better than many commercial programs.



Yes in theory. But it won't happen very frequently that you run across a CD-Rom drive that can read audio at this speed with EAC because of the way EAC works, using statistical methods and checksum verifies to ensure 100% bit-by-bit exact rips



Yes. There is some adjustment to be done regarding offsets to guarantee that you will put the data exactly where it was, but this usually just means that the music will start some milliseconds earlier or later compared to the original. I think almost anyone can live with that...

I hope I didn't say anything too blatantly wrong...

Kblood:

Thanks for the answers! So if I understood this correctly, it is possible to both rip and burn an exact copy. I will do a test at home and see if it sounds the same as the original disc. I will burn it on special audio CD-r discs too.

This is most interesting for me who is an audiophile

I have downloaded EAC for ripping. Is there anything else I should consider before testing?

Muppfarmor: Please also choose the right forum for your questions. There's a ripping/CD-r etc. forum in this board.

I'm not an expert of CD-r issues, but if I'm not mistaken, if you burn with not so good burner (even the CD-r disc brand may have effect), you will definitely increase the chance of jitter in the playback phase, especially depending on the clock-circuit and buffering of the CD-r drive.

Check out: http://www.digido.com/jitteressay.html

JohnV:

Sorry, will do

Special audio CD-r discs: not worth it. Honest. This is digital, 0s and 1s, it's either correct or not. "Special" "audio" CD-r discs only have "special" a digital flag that standalone CD-r burners (the ones you plug as a module to a Home stereo system) check for before using them. So if this flag exists, they will happily burn them. If it doesn't, they will reject them. So it's just a hoax to make standalone CD-r burner owners pay double price (usually) for the same thing "standard" CD-r's are made of.

I'd say just be careful to buy nice quality CD-r's, mostly pay attention to the covering on the side where you write the titles (with a soft tip pen!) since it's the layer that protects the reflective layer from damage. And scratches on the reflective layer are the MOST harmful to your CDs!! (original, burned, whatever!)

Of course, before testing, try as hard as you can to get a nice couple of headphones attached to your soundcard. Also, DISABLE right away the WinAmp's equalizer, widely known for introducing very audible errors. Better yet, use ABX and use the wavs decoded from your mp3pro and mp3 ripped tracks for comparison, as this will get rid of (most of) external influences. And, needless to say, get a LAME 3.92 binary!

Then, if you want to compare MP3Pro at 64kbps with MP3 at 128kbps... try using this switch for your MP3 LAME encoded file: --alt-preset 128 (or --alt-preset cbr 128 if you so desire to test also CBR mp3 files...)

Then, test further on: --alt-preset standard, --alt-preset extreme, and --alt-preset insane

Report your feelings afterwards! Have fun! You WILL be impressed.

Oh, by the way, if you want to try a different approach, it will not be scientific, but maybe enough to get you convinced: have a friend play for you the different songs in Winamp without you seeing which one he chooses. Make sure you DON'T use Thompson's mp3pro WinAmp plugin for playback of the standard mp3 files... (there's an option for that in WinAmp plugin's properties to enable/disable mp3pro plugin)

Ooops! Yep, we have gone terribly off-topic...
So: Test also Ogg Vorbis 1.0 at 64kbps!!! (-q=0 should give you that)

Kblood:

The test I want to perform is not between MP3 codecs and so on. I want to test if I can here any difference between a copy and the original disc. Therefor I want to make sure I rip the right way and then burn it the right way.

I'm now taking my following questions to the right forum But thanks again for your info!