No Disc Posted January 11, 2003 Share Posted January 11, 2003 rf3iicrazy - The only thing I can think of that would cause a CD duplicate to sound any different from the orginal would be if your workflow is somehow flawed. Are you making a CD exact bit-for-bit copy or ripping the audio tracks to somthing other than AIFF format? AIFF is the format that is on CD and is not compressed. Your burning software may have settings to determine how you want Audio data to be treated. Treat an Audio CD as any DATA CD... Make a bit-for-bit copy and you should not notice a difference. Check the preference settings of your copying software. - tb Quote Link to comment Share on other sites More sharing options...
No Disc Posted January 11, 2003 Share Posted January 11, 2003 justin_tx_16 The new compressed format to beat is mp4.. or AAC Advanced Audio Coding. snip -------------- AAC was developed by the MPEG group that includes Dolby, Fraunhofer (FhG), AT&T, Sony, and Nokiacompanies that have also been involved in the development of audio codecs such as MP3 and AC3 (also known as Dolby Digital). When compared side-by-side, AAC proves itself worthy of replacing MP3 as the new Internet audio standard. Take a look at these AAC advantages over MP3: Improved compression provides higher-quality results with smaller file sizes Support for multichannel audio, providing up to 48 full frequency channels Higher resolution audio, yielding sampling rates up to 96 kHz Improved decoding efficiency, requiring less processing power for decode The Data Speaks for Itself In numerous comparison tests, AAC comes out on top. Check out these impressive results: AAC compressed audio at 128 kbps (stereo) has been judged by expert listeners to be indistinguishable from the original uncompressed audio source.* AAC compressed audio at 96 kbps generally exceeded the quality of MP3 compressed audio at 128 kbps. AAC at 128 kbps provides significantly superior performance than does MP3 at 128 kbps.* AAC was the only Internet audio codec evaluated in the range Excellent at 64 kbps for all of the audio items tested in EBU listening tests.* For more info and an Audio Gallery .... http://www.apple.com/mpeg4/aac/ http://www.apple.com/quicktime/gallery/aac.html http://www.vialicensing.com/products/mpeg4aac/standard.html Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted January 11, 2003 Share Posted January 11, 2003 Suprised you are saying this, Tim. I have found a difference most of the time. And I am a stickler about getting settings right. If you came down here, I could point them out to you. kh Quote Link to comment Share on other sites More sharing options...
lynnm Posted January 11, 2003 Share Posted January 11, 2003 Frankly speaking GIGO is a true statement but logically the obverse is not true. In other words the fact that a recording system is presented with high quality input does not guarantee a high quality copy. This is true regardless of the recording technology. MP3 IS by definition a "lossy" compression scheme because it is a compression scheme. Lossy or Non-Lossy as applied to compression schemes is merely a matter of definition. There is no way to somehow squish 1's and 0's ,( a bit is either an on state or an off state) into smaller 1's or 0's . What can be done however is create an algorithm that states that every bit (ie every 1 or 0 ) shall be evaluated in relation to the 1's and 0's around it and handled accordingly. Therefore algorithims may be constructed in such a manner as to selectively drop bits according to the context within which they occur. The algorithim is of course created by programmers who are typically working within a number of constraints imposed by musical/mathematical rules/laws + existing standards + employer requirements + typical equipment capabilities etc. The fact that a custom built $500,000.00 DAC exists somewhere that can provide superior processing to anything currently available in the consumer market is essentially useless if in addition to its outrageous cost it requires a total redesign of existing technology and furthermore is not backward compatible to previously available technology. It is therefore reasonable to state that there is no such animal as a perfect copy and further to suggest that given that every copy is imperfect that some listeners will be able to detect the admittedly small differences between the original and the copy. Those differences when percieved will be percieved as very large even if laboratory tests would seem to indicate that they are of no significance. Quote Link to comment Share on other sites More sharing options...
No Disc Posted January 11, 2003 Share Posted January 11, 2003 I'm surprised that your experiencing a difference knowing your exacting nature... Perhaps you can go into more detail as to your CD copy workflow... i.e. Do you make a burn image first on disk, and then burn to CD or do you burn disc-to-disc with a read drive and a write drive? Do you perform a verify and checksum on the original vs the copy? This topic has been discussed extensively in the AA Digital forums and I've always sided with the bits are bits crowd. There are error correcting buffers on players, so assuming the copy is written without errors or flaws, it should play identical to the original. - tb Quote Link to comment Share on other sites More sharing options...
cornwaller Posted January 11, 2003 Share Posted January 11, 2003 Lynnm, You are exactly correct and I tried to point out this algo deficient regime in my first post on this topic and it seemed that everybody was so intent on disagreement they couldn't see the logic! Oh well, let them wallow in their own complacency. I guess this copying-burning will ultimately seperate the audiophile from the computer-whizz-bang- I-have-to-copy-this-fast-frenzy. A true musical copy can only be made from a good original CD by the use of an equally good bit-for-bit burner. Period. That's my story and I'm stickin' to it! Cornwaller Quote Link to comment Share on other sites More sharing options...
mkl Posted January 11, 2003 Share Posted January 11, 2003 Maybe I'm reading this post wrong and I just don't understand what you're saying. Let me go through it point by point. (Disclaimer: I am a professional computer programmer who has worked on/with several compression programs/algorithms) "MP3 IS by definition a "lossy" compression scheme because it is a compression scheme. Lossy or Non-Lossy as applied to compression schemes is merely a matter of definition." I'm not clear what this is saying. All compression schemes are NOT lossy. It seems like you are saying all compression schemes are lossy and lose data. This just isn't the case. Some schemes when you uncompress the data you get the exact same data that you had before compression, others you can never get the original data back after compression. MP3 is one of the ones where you never get the original data back. "What can be done however is create an algorithm that states that every bit (ie every 1 or 0 ) shall be evaluated in relation to the 1's and 0's around it and handled accordingly. Therefore algorithims may be constructed in such a manner as to selectively drop bits according to the context within which they occur." Bits are not "dropped" in the way they can not be recovered in a non-lossy compression scheme. In a non-lossy compression scheme patterns are typically found and shorter strings are used to represent these strings throughout the data. For a general idea of how this works...imagine I was trying to compress a file that had "mklmklmklmklmklmklmkl" in it. Instead I wrote "mkl*7" to the file, and in my decompression program, it knew that anything with a *7 after it, meant the previous string 7 times in a row. I have just used 5 characters to represent 21. When my decompression program runs on "mkl*7" it produces "mklmklmklmklmklmklmkl", the exact same data in the original with no loss of data. This is an oversimplified example, but hopefully it will allow you to see how nonlossy compression works. In a lossy compression scheme, bits are dropped and they can never be recovered. This is usually used for things that dont need the exact bits reproduced (like mp3 copies of music, where they arent expected to be perfect, they throw away the high and low tones in the music. Or jpegs, where they do a sort of average of the colors around a pixel to decide what information to store.) "It is therefore reasonable to state that there is no such animal as a perfect copy " This simply isnt true. Perfect digital copies,are perfect digital copies. This happens all the time. When something digital is copied, the same thing comes out the end. If this were not true, it would be like an analog copy, where every time you make a copy of a copy more and more errors propogate through the bits. If you take an mp3 file on your harddrive, make a copy and send it to a friend, who makes a copy of that copy and sends it to a friend...the 4000th person to get acopy of a copy has the EXACT same bits as the original mp3. If this were not true, burning/compying computer programs would not be possible. If even 1 bit on a binary computer file (like an executable program) is changed it would not be the same program. This is easy to see : Lets say you have just one binary number and that binary number is 2. (10 in binary) If the error could be introduced as the program was copied you could end up with 01 which is 1, or 11 which is 3 or 00 which is 0. These kind of changes in a binary file would leave it unreadable in most cases. Every bit is important. That is why if you are transfering a file over a modem or network and somehow even one bit gets changed incorrectly in transmitting, you can have a curropted file. So it is true that there are PERFECT copies. I can copy an audio cd, onto a blank cdr, and run a "diff" utility, which displays ANY difference in even a single bit, and both copies will be EXACTLY the same. Unless ofcourse you have a faulty cd burner, but that is simply an exception, and you'd know it, because if you tried to copy a file it would come out changed or corrupted. Lets sum it up: 1. Compression schemes do not all by definition LOSE any data. A. Lossy compression (like mp3,jpeg etc) lose bits that you can NEVER get back. b. Non-lossy compression (like .zip etc) compress the data , but you can get the original data back at any time. 2. True digital copies are perfect by definition. Every digital copy of a digital file/media is going to be exactly the same as it was going in. (unless intentional errors are introduced, but thats a whole different story) Wow, that was entirely too long of a post. I hope it explains things however:) -mkl Quote Link to comment Share on other sites More sharing options...
No Disc Posted January 11, 2003 Share Posted January 11, 2003 Tom - The problem you and Kelly are experiencing is related to Jitter. Jitter would cause a CD copy to sound inferior due to timing errors. If someone copying a Audio CD does not follow correct steps in copying a CD, or uses poor equipment (Software / Burner) it can induce jitter. All the ones and zeros are the same, but there timing is off. The timing information or clocking is critical when copying CDs correctly. It's boils down to the workflow involved in copying the CD. A few guidelines I always follow... Allways make a Hard Disk image, do not copy from original to copy in one step. Take two steps. Make a copy onto the hard disk first, then after you have made a "cd image" on the hard disc, then produce the copy. Burn at a slow speed 1x 2x 4x - use good media Don't do anyting else with the computer when you are doing the copying. See the tips below that were posted to AA. They include good advice. where the problem is... http://db.AudioAsylum.com/cgi/m.pl?forum=digital&n=13656&highlight=cd+copy+jitter&r=&session= a cd copying procedure http://db.AudioAsylum.com/cgi/m.pl?forum=digital&n=37190&highlight=cd+copy+procedure&r=&session= suggested software http://db.AudioAsylum.com/cgi/m.pl?forum=digital&n=44116&highlight=jitter+cd+copy&session= FWIW - There are many who feel copying a CD can IMPROVE the sound quality if jitter is present duing the glass mastering of a CD. It's a HUGE problem in the industry and a reason some CDs sound like crap. Read this... you'll understand why... http://www.rogernichols.com/EQ/EQ_2000_02.html Note that this guy discovered the problem by making a CD copy which removed the Jitter from the test master. - tb Quote Link to comment Share on other sites More sharing options...
jonjacques Posted January 11, 2003 Share Posted January 11, 2003 I used Sonic Forge to record albums to my hard drive in wave format. I then burn cd's using Nero. Santa brought me a palm pilot for christmas so I intend to convert some of the wave files to MP3 for listening on the road. I haven't done a side by side with commercial records or MP3 format. Should they all sound the same or different? jonjacques Quote Link to comment Share on other sites More sharing options...
AndyKubicki Posted January 11, 2003 Share Posted January 11, 2003 I copied a redbook CD and when played, the copy has pops, which I assume are corrupt data. When I mentioned this problem to a friend who has burned a lot of music, he told me there is a program which compares the info as you burn, but I don't remember the name...it was exact copy or something to that effect. Anyone hear of this program? I will try and find out from him again too and will post if I get the name. Quote Link to comment Share on other sites More sharing options...
No Disc Posted January 11, 2003 Share Posted January 11, 2003 jonjacques, First off, CDs at 16bit / 44.1 Khz sampling will never equal the quality that is in the grooves of Vinyl records. It's a trade off. More portability for less quality. Going to mp3 will reduce the quality even further because it's a lossy format. Will they sound the same... no. Will you notice it on the road when driving 75 mph with the windows open... probably not. - tb Quote Link to comment Share on other sites More sharing options...
No Disc Posted January 11, 2003 Share Posted January 11, 2003 Andy, You are correct. Those pops are indications that the sound data is getting corrupted between the reading and writing phase. If the original didn't have the pops of course. There are many programs out there, not all of them created equal! See this link... http://db.AudioAsylum.com/cgi/m.pl?forum=digital&n=44030&highlight=exact+copy&r=&session= - tb Quote Link to comment Share on other sites More sharing options...
Jolly Roger Posted January 11, 2003 Share Posted January 11, 2003 Yea, I have agree with lynnm. Why would simple things like jitter not come into play here that is inherent to all pcm cds? Quote Link to comment Share on other sites More sharing options...
AnalOg Posted January 17, 2003 Author Share Posted January 17, 2003 All, I believe I have resolved my concerns regarding cd burning. Taking the advice of some of the feedback I received here, I now copy cd to cd at 1x. I did A/B comparisons and to my deaf ears I can not decifer the difference. Thankz for all your inputs, much appreciated. Tom Quote Link to comment Share on other sites More sharing options...
Audible Nectar Posted January 17, 2003 Share Posted January 17, 2003 I have much info to share with you, but no time to do so. See if a search for "exact audio copy" gives any results on this forum (those posts were made by me). It will explain that much of the problem is in the rip. Sorry I can't get more specific right now, but I don't have time to get into it, but I have discussed this on the forum before. When I have time, I'll get back to this - but it may be a while. Quote Link to comment Share on other sites More sharing options...
AnalOg Posted January 17, 2003 Author Share Posted January 17, 2003 Cool, Thankz again for the feed back Tom Quote Link to comment Share on other sites More sharing options...
artto Posted January 18, 2003 Share Posted January 18, 2003 Heres what Ive experienced, & let me also say that I agree whole heartedly with tbabbs post. There are any number of factors that can affect the quality of CD-R burning, & therefore its playback. Windows is not exactly what one would call the most stable operating system in the world. Theres always lots of stuff floating around in there, and, unfortunately, you cannot turn everything off. To avoid as many conflicts as possible; 1. Close down all programs except explorer & systray from the close program dialog box. 2. Run only the software you need to copy or burn. 3. DO NOT have any other programs/equipment running. 4. Stay off the internet. Disconnect your broadband connection if you have one. 5. Machine maintenance: hard disk defrag, windows system check (with something like Norton Utilities), check hard disc for errors, shutdown machine & reboot before burning, etc. In my experience, the best results are obtained by first ripping the file from the original CD and then burn the copy. Whether or not you are going to be able to do a direct copy to burn is highly dependent on the software & computer you are using, CD playback drive & the CD burning drive. Even if the playback drive is a faster (say 24x or more) speed drive, does not guarantee that actual the transfer rate (through-put) from drive to drive is good enough. Other factors that Ive found affect the burning process are (some obvious) the speed of the machine, the amount of memory, the kind of memory, how the memory in your machine is allocated (ie: some machines share memory for various things like video while other have additional dedicated memory & processors), the kind & speed of the hard disk, and the original CD or file you are trying to burn. For instance, if you have a file that has a lot of tracks on it (ie: 27), and the disc is being burned edge to edge taking up nearly all the available recording time on the disc, these discs seem to be prone to more errors and/or burn failures, especially if you are burning multiple CDs (either many CDs with different files, or just multiple copies of the same file). Contrary to popular belief, SCSI drives are typically not the best choice of hard drive for this application. SCSI drives tend to eat up a lot of system resources which can affect the burning process because of the aforementioned considerations. They are not recommended by the software manufacturer I use (Sonic Foundry). In my experience, Roxio Easy CD Creator is one of the worst pieces of Windows software ever made. I use it for data backup, but thats it. Nothing with music. Ive mastered dozens of recordings and burned literally thousands of CDs. Some for bands that Ive played in, some for other bands (rock, blues, jazz and American classical banjo). I also record, master & produce live-in-concert performances for a local Chorale 2 or 3 times a year in which Ive had the honor of recording some of their guest artists some from the likes of the Elgin, or Chicago Symphony Orchestra. Main CD burning equipment: Dell Precision Workstation, dual 866 PIII, 1GB dual channel 600Mhz Rambus RAM, dual Maxtor 10,000rpm 60GB hard disks, Lite-On (what ever that is) LTN483S 48x CD drive, Sony CRX140E CD-RW drive, Windows 2000, software; Sonic Foundrys Sound Forge & CD Architect. Ive also heard good things about the Plextor CD-RW drives. I burn at 4x on this machine. 2x on my slower one. Sonic Foundry told me the software is actually optimized to burn at 2x. And, it was not intended as a mass production product. For the Chorale I usually have burn runs totaling 85-150 discs. I can usually burn about 20-25 discs in one session that have 20 or more tracks that nearly fill the entire CD. The fewer the number of tracks and/or the amount of recording time, the more CDs I can burn without failure. And just because the software, at the end of the burning session says all 20 discs completed without failure, does not guarantee all of them are actually defect free. I shut down the machine for a few minutes & reboot after doing a 20-25 disc burn. There also seems to be differences as to how tolerant a CD player will be to these disks. And from what I can tell, it seems to be primarily related to error correction. I had one recording I mastered that would not play (skipped & jitter) on my old Revox CD player (circa 1984?). It played fine on everything else, even a cheap BrandX Walkman from WalMart. The old Revox basically doesnt have much in the way of error correction other than the traditional CIRC computer technique of interleaving. As for MP3, I dont use it. Great convenience (which I dont need), but inferior sound quality. IMO, somewhere between a good tape cassette being played back on a top notch machine, and CD, but definitely falls short of CD, SACD or vinyl. Oops, I take that back. I do have a ton of bootlegged live performances of favorite artists in MP3 downloaded from Napster before they went under. But these are obviously for the merit of collecting music that in all likely hood will never be commercially released. Eventually Ill transfer them to CD. Quote Link to comment Share on other sites More sharing options...
AnalOg Posted January 18, 2003 Author Share Posted January 18, 2003 Thankx for the extensive post, and sharing your knowledge in this matter. I will definetly get a look into some knew software & equipment wise I'm o.k.. Thankx again Tom Quote Link to comment Share on other sites More sharing options...
prodj101 Posted January 18, 2003 Share Posted January 18, 2003 you could try using differen't discs. like more high quality ones. I use microboards, and so does this guy who works in a studio I know and they sound pretty nice. but they're like 1.10 each, so alot more spendy than other stuff. but still better than spending 15 bucks on the original cd. Quote Link to comment Share on other sites More sharing options...
artto Posted January 18, 2003 Share Posted January 18, 2003 I've used many kinds of discs. And after burning thousands of CDs I can't honestly say that nowadays one brand works better than another. Most of these discs are coming out of the same OEM manufacturing plants with different brand names (or no name bulk packaged stuff). 5 years ago or so, certain discs seemed to prefer certain CD-RW drives. This no longer appears to be as critical as it was then, or I'd be seeing increased defect rates in certain brands of discs which would definitely show up in the number of returns I get from the sales of these CDs. I currently get 1 to 3 returns per 100. And that number hasn't changed for several years now regardless of which brand I use. I've purchased Microboards discs on sale at Guitar Center for as little as 20 cents (50 disc pack) with rebate. Quote Link to comment Share on other sites More sharing options...
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