Media FAQ's
Here are some of the common questions asked about media. This will be updated over time. If you do not see your question listed here, try reading the answers anyway, you might find your answer there. Posts regarding the content of the FAQ are welcome, but OT posts will be removed to avoid clutter.
1) Why should I test my discs?
2) Do discs wear out?
3) What's a "good burn"?
4) What are errors?
5) How do I test for errors?
6) What if I see read errors on my burned discs?
7) What makes media "good" or "bad"?
8) How do I know if I'm buying "good" media?
9) What media works best with my drive?
10) What's all this about dye?
11) How do I know who made my discs?
12) How fast can I burn these discs?
13) Can I write on my discs?
14) What's the difference between "audio" (music) discs and "data" discs.
15) How fast can I burn this CDRW disc?
16) What kind of media will work in my old audio/car player?
17) Is it better to burn at a lower speed?
18) What is a DVD Media code (MID) ?
1) Q: Why should I test my discs?
A: There are no guarantees that your combination of drive, media and software will produce a "good burn" every time. Even if you always use the same media, variations between batches and changes in the brand's supplier can affect the performance of that media. In some cases, even discs from the same spindle have been known to produce widely varying results with identical burn scenarios. Another good analogy is this: most of us know that we should regularly check our hard drive for bad sectors, as time and use can cause degradation. The same is true of optical discs.
2) Q: Do discs wear out?
A: Of course, rough handling, dirt and poor storage techniques will physically damage a disc, and eventually render it unreadable. There is also another type of "wear" that discs go through that is related to temperature, moisture and ultraviolet light. These are the stresses that disc makers often use to test media's ability to withstand aging. If you believe the marketers of media, discs will last for "100 years" and "thousands of uses". The truth is somewhat less definite. One factor that has been demonstrated by many users, is that discs that do not burn well and show higher error-rates tend to degrade much faster. In worst cases, they can fail in as little as a few weeks, but months or years is more likely an accurate prediction for the less reliable of the media that's out there. The media should last for many years with careful storage and use. Remember that all media is "burned" with a laser, heat is the process that makes the dye change characteristics and heat will make it unreadable again. "Re-writable" media is well known for being less stable than "write-once" media. In spite of the seller's claims to the contrary, re-writable discs may have a real-world life of only a few dozen write-erase cycles, or less, before they start to have problems with read-errors.
3) Q: What's a "good burn"?
A: When a disc responds correctly to the application of heat, the laser creates what is called "pits" and "lands" on the disc. These are what gets read by a drive when you are using the disc. What makes the disc more or less "read-able" is the accuracy in the creation of these, (more precisely the edges of them). If the media cannot properly respond to the laser, or if the laser is not properly calibrated, the edges become blurred or jagged, and reading becomes more difficult. A "good burn" results in a disc that can be read by a wide variety of drives at varying speeds. A marginal burn results in a disc that can be read by only some drives (the "better readers"). A marginal burn may also result in a disc that can be read, but will have many read-errors that cause slow reading problems and even corrupted data. Of course, a bad burn results in a "coaster" that no drives, or very few drives, can read.
4) Q: What are errors?
A: Errors, for the purposes of this discussion, refers to "read errors". They occur as a result of a problem in the process of reading those pits and lands. In one sense, the errors do not exist on the disc, but occur in the reading process. How a drive responds to those errors can vary a bit, and the result is that some drives are better at reading than others. Thus, a disc that causes read errors on one drive may not on another. Or the amount of errors may vary from one drive to another with the same disc. There are different types of errors, the most common of which are referred to as C1 and C2. A discussion of what these really are, how they are measured, etc. is not relevant here. In very general terms, C1 errors are the most common, and all discs cause them. They are corrected by the drive and do not generally cause any trouble. One measurement of a disc's quality can be the level of C1 errors that are occurring, less is better. However, even relatively high C1 rates are not usually the cause of any problems.
C2 errors can best be described as the next level of error. With these, a drive may have to re-read that sector to correct the error, slow down to read it, etc. Again, drives may differ in how they respond to this level of errors. If the drive slows, it may read a section with no C2 errors where it would report many C2 errors at full speed. So with some marginal discs, one drive may slow down and show no errors, another drive may read it at full speed with some errors, or another may read it at full speed with LOTS of errors. And again, here we are looking at a disc that may be unreadable in some drives. Most of us here feel that there is no acceptable amount of C2 errors on a disc, and the drive should be able to read a disc at full speed. It's also important to note that these are also corrected errors, and you should not see data corruption or failures in the reading process.
There is another level of error , (uncorrectable), that results in an unreadable sector. This produces corrupted data, possible read failures and maybe even a "coaster" that cannot be read at all. These are bad, and the worst part is that if you aren't testing your burns, you may not even know it's a bad disc or data has been corrupted. Again, there are many different designations and classifications of errors, but for our purposes, these 3 types are more than adequate to describe the situation and provide a means of comparing one disc to another.
5) Q: How do I test for errors?
A: There are several programs available for checking discs for read-errors. The most common right now is CDSpeed, which is now included with Nero, and can also be downloaded for free at CDSpeed . At this time, CDSpeed only checks C2 errors on most drives. In case you haven't noticed, there are a lot of LiteOn drives out there, and LiteOn users here. There is an oft-referred to program out there called WSES that also, (among other things), scans discs for read-errors. You can read about WSES in the local LiteOn Forum . Because this program is not officially released, and because it also has the ability to kill your drive, it will not be provided or discussed here. A newer entry into the field is called CD Doctor. Thanks to the most excellent work by Ian and cfitz at CDRLabs, this Japanese adaptation of a another testing program is now available to the public and in English. To get it, please visit the CDRLabs Forum and read the entire thread about this program. A download link is provided there. The zip file that the program is delivered in is password protected, but the password is provided in the "read me" file. The object is to get you to read the "read me" file. This program displays both C1 and C2 type errors, but is somewhat limited in a couple ways. If a disc has high error rates, the display will not work very well. It only works with Sanyo and LiteOn drives for the most part. You must also have ASPI installed for this program to function, version 4.60 is recommended, and can be downloaded at Adaptec
A newer entry into the testing arena, Kprobe, is available for download and discussion in the media forum . This nifty program is for LiteOn drives only, and also requires the ASPI driver (included in the install version). It combines many of the best features from WSES, CD Doctor and CDSpeed, and has the advantage of being designed to test DVD media and DVD burners as well.
For most purposes, CDSpeed is adequate for checking read errors, and does not require installing any other drivers. However, your drive must be capable of reporting errors, many are not. Again, LiteOn rules in this area.
Simply start CDSpeed, insert a burned disc in the drive and select that drive from the drop-down list of drives. Then go to "extra" and "Quality Test". You can also use the "Scandisc" test which will provide a more graphical display of those problem sectors. I prefer Quality Test because it gives a display of read speed and actual error rates. Both functions are reporting the same errors. With Quality Check, it's best not to use your system while the test is running, as multitasking can cause blips in the speed (green) line that make the graph a bit confusing to look at. Just visit the media test threads to see how the graphs look.
The main purpose here is to be able to check for obvious error problems and also to compare the results of burning with different media and at different speeds. no 2 tests will look exactly alike, except for those that show "0" errors. Due to the nature of what is being reported, even 2 tests of the same disc may not look the same, and this is normal. You can also use these tools to compare one drive to another with the same disc, to see which reports fewer errors.
Again I wish to stress that you are not just checking the "quality" of a disc, but also the ability of the drive to read the disc, and the ability of the drive to report those errors. All the variables discussed above will come together to produce what you see on the graph.
There are also a variety of file-checking utilities available, one is included in CDSpeed's "Scandisc" test. There is another file checker in Nero, it's the "verify" option in the burn window. The Nero verify test will compare the files on the burned disc with the files on the hard drive. The Scandisc file checker is just reading the files on the disc and reporting that they are/are not readable. Various other programs are available for checking file integrity. My feeling about all of these is that they have limited value. You will see a considerable number of C2 errors being reported long before any data corruption occurs in most cases, So just because the files test OK, that doesn't mean you have a good burn or a reliable disc.
The subject of error checking is involved and hotly debated, but for the purposes of doing some simple comparisons, this information should be adequate to get you started. Don't be afraid to waste a few discs in the name of testing. It's less of a waste than not testing. The most expensive disc is the one that fails.
6) Q: What if I see read errors on my burned discs?
A: Well, there's nothing you can do to change those reported errors, unless it's a RW disc and you can erase it and start over. My feeling is that there is no acceptable level of C2 errors, and the read must be completed at full speed for the disc to pass. These errors are the result of any one, or several, of the variable factors discussed here, so changing any of those variables can make a difference. The obvious solution is to change media and/or slow the burn speed. I suggest that if you see a few C2 errors, that you should lower your burn speed on that media by one "notch" and try again. (i.e. drop from 40x to 32x burn speed.) Getting higher quality media is not always easy in all parts of the world, so lowering your burn speed may be your only solution. If your drive is consistently producing errors on a wide variety of media and at most speeds, you may have a bad drive. Errors may not always be seen in the same area of the disc either. Sometimes they will be near the end of the disc, where relative speeds are highest. But, due to the way the drive changes the laser calibration during the burn, errors can also be seen only in the first part or middle part of the burn.
Many drives will only produce consistently error-free discs on a narrow range of media brands, this is what is known as being "picky". But it's important to keep stating here that it's the combination of media, drive, and burn speed that creates a good disc.
7) Q: What makes media "good" or "bad"?
A: This can become a long and fiery debate. Everyone has a preference for a certain brand, certain dye type, etc., etc. There is no such thing as a list of "good" or "bad" media. There is no good or bad dye type. It's the combination of drive, media and burn speed that makes or breaks a disc. The manufacturer of the discs can take a good dye and make it bad, and vice versa. The plastic disc that the media is constructed on must be perfectly flat in order to proved a smooth reflective surface for the dye, and the list of things that go into a "good disc" continues. As burn speeds increase, we are rapidly reaching the end of the possibilities for media, at least at it's current prices. So, a good disc is one that works for you in a reliable way. You have to test the media in your own drive to know.
8) Q: How do I know if I'm buying "good" media?
A: You don't. You can buy the brand that has consistently worked for you, or others, but never assume that it will perform exactly like that last spindle did. Price is no indicator either, as often the best media can be had at bargain prices, (or high prices), under a variety of labels. Poor media is also sold with well-known names on the label.
9) Q: What media works best with my drive?
A: I refer you to the above discussions, there is no generalized answer to this question. Even "identical" drives can show different error rates on the same media at the same burn speed. Sorry, you gotta buy some and test it. Consult the media tests and get what is working well for others, then test it. Then test it some more. There is also a very extensive media thread at CDRLabs HERE
10) Q: What's all this about dye?
A: Phthalocyanine and Cyanine are the 2 major types. You will see other references to Azo and a range of things like gold, silver, etc. Another hotly debated topic, and my own opinion is that it makes no difference what dye type is used. The various disc makers use differing formulations of each type, some work and some don't in a given drive. It's the quality control and care that the manufacturer uses that makes a good disc. If you're buying discs based on the dye type, you may be missing out on some good discs. If your drive only "likes" one type, maybe you should consider a new drive.
11) Q: How do I know who made my discs?
A: There is a code written on every disc, called the ATIP(ADIP). This contains information about dye type, possible maker of the disc, length of the disc (size) and type of disc. (R, RW, audio, video, etc.) Many programs can read this information. Nero, Nero InfoTool, and the LiteOn utility: SmartBurn Media Checker are all widely used. DVDIdentifier is a popular tool for checking information on DVD media and drives. Many of the other burning programs are also now reporting the ATIP/ADIP information on media. The SmartBurn utility also reports the max speed that the disc can be burned at, on a LiteOn drive with SmartBurn enabled. Some of these "readers" of ATIP information may report different disc makers, on the same disc. The codes are not always reliable, and are sometimes "faked" by unscrupulous media sellers. But with well-known media sellers and brand names, the codes are usually reliable.
12) Q: How fast can I burn these discs?
A: One of the most often asked questions. If your drive is equipped with SmartBurn, BurnProof or one of the similar features, the decision may be made for you as far as the maximum allowed speed is concerned. This "maximum" speed is just that. It is not necessarily the BEST speed for burning that disc. Your drive's maximum burn speed may not be available in the software with many discs. Similarly, the "rated" or "certified" speed on the label is not necessarily the best speed for that media. Even though the rated speed may be 48x, your drive may not offer that speed in the software. Your drive uses a database of media ATIP codes to determine what is the best speed for the disc. Updating your firmware is one way to be sure the drive has the latest information about media. The only good answer to this question is that you have to try it and see. If your drive and software allow you to turn off the speed restriction, you can try burning the media faster, but the results may not be good. Test for errors and make your own judgment as to how fast you can burn that media. There are examples of 16x rated media that can be safely burned at 48x, and examples of 48x rated media that cannot be safely burned at 24x. It all depends on the golden triangle of "drive - media - burn speed" and how they work together.
In the case of DVD media, the decisions on burn speed are taken away from you. Available burn speeds ar set in the drive firmware, and only a firmware change can alter those speeds.
13) Q: Can I write on my discs?
A: (See this thread) As long as you are careful, yes. Many people use the tried and trusty "Sharpie" permanent markers. There are also a number of "CD Markers" being sold, but they amount to the same thing. Please note: you should only mark on the BACK of the disc! Some people have reported that markers have caused erosion of the lacquer coating on the back of their discs, but this should not be a problem with good quality media. I've got some discs that were marked on several years ago that are still fine. There are also discs available that have a plain white coating on the back that is suitable for inkjet printing, these can be written on with most anything, if you're carefull. 14) Q: What's the difference between "audio" (music) discs and "data" discs?
A: Audio discs cost more because they pay a royalty to the poor starving recording companies. They carry a coding on the disc that identifies them as "audio" discs. Stand-alone audio recorders will only use this type of disc. Your computer drives can use either kind equally well. Physically, the 2 types of disc are identical. You may find that your computer's drive will identify audio type discs as being burnable at no more than 12x, even though they may be rated for 32x or more. This is due to the SmartBurn/BurnProof type features, and can be circumvented by turning this feature off in your software. (if this option is available). Unless you use a stand-alone audio recorder, there is no reason to buy audio-type discs.
15) Q: How fast can I burn this CDRW disc?
A: That depends on the type of CDRW it is. Currently, there are 3 types, "1x4x", "4x10x-12x" (AKA High Speed), and "12x24x", (AKA Ultra Speed). Each type requires a drive that is specifically built to write on that type of disc, and each type can ONLY be burned at the rated speeds. So, if you buy "High Speed" or "Ultra Speed" discs, you can't use them in your 4x CDRW drive. However, the faster drives are backwards-compatable, so you can use 4X media in a 12x CDRW drive and in a 24x CDRW drive.
16) Q: What kind of media will work in my old audio/car player?
A: This is a tough issue, many older players are not designed to read CDR's, and can be very picky about what media they will read. Some people report that using very slow burn speeds will increase compatability, but in fact the type of media you use may be more critical than the burn speed. As a last resort, you can try slow burn speeds, but I suggest keeping it above 16x unless you have some older media that is rated below 16x speed. The most common media that is compatable with older drives is the darker Cyanine-type such as TY (Fuji made in Japan), or Verbatim DataLifePlus. It all depends on the type of laser in that old drive, so if the darker Cyanin-type discs don't work, try the lighter Pthalo-type discs like Ritek. Some audio players will not track anything past 74 min, so be sure to limit your recordings to 74 min. Some players will not accept 80min CDR's, even with only 74 min burned on them. So as another last resort, try some 74min (650MB) discs if you can find them.
17) Q: Is it better to burn at a lower speed?
A: Have a look at THIS thread for some test results. The answer is that it's a question of degrees. Very slow burn speeds are not good when using high speed media in a high speed drive. It's also true that you can almost always improve the quality of your burn by lowering the burn speed a "little bit". For example, my 52x drive can produce very acceptable quality discs at 48x on the right media, but quality improves even more if I burn at 40x. I see very little, if any, improvement in quality by lowering the burn speed to 32x, and decreasing quality below 24x. With older, low-speed rated media you might see better quality at very slow burn speeds, but again the best thing is to try it and test it.
09-01-2003
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