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DVD知识库/.2401087，
http://www.dvdfaq.com.cn原文地址：http://www.cdfreaks.com/article/202/1
一直都想做这方面的对比，可是时机没有了，以前还有机会可以用用des，可惜没有利用好做一个这方面的对比测试，让老外先做了，后悔呀。只有看看老外的了，不过在碟片检测领域，cats要比des nb些，听说而已。
关于该文的翻译摘要，稍后补上。
The idea of this article is to compare disc quality scans obtained using professional tools (AudioDev’s CATS) with the ones obtained from standard PC drives. We will also discuss about the correctness, accuracy and usefulness of these tools when it comes to disc quality measurement. Note that the comments and conclusions of this article reflect the views of CDFreaks and not the ones of AudioDev.
Company information: （可以不用看，介绍生产cats的公司AudioDev）
Before we continue with this article let us take a look at the company information and what AudioDev offers at: www.AudioDev.com
AudioDev in brief
AudioDev is a world-leading manufacturer of test equipment for quality control of optical media such as CDs and DVDs. The head office is based in Malmö, Sweden. AudioDev has been listed on the Stockholm Stock Exchange since September 2000. AudioDev’s products are sold under the brands CATS and Go!. The products in the CATS series are high precision analyzers for quality testing for all formats on the market. The Go! series is optimised for production control. AudioDev also offers an extensive service network as well as customised training and independent test analyses through AudioDev’s TestCenters.
The industry and our customers
AudioDev’s operations are focused on the market for optical media. This market consists of:
- Manufacturers of optical media (CD and DVD).
- Manufacturers of optical media players/drive units.
- Content owners who use CDs and DVDs to distribute their products.
- Manufacturers of production equipment (test equipment, line manufacturing etc).
- Consumers of optical media.
AudioDev’s client list includes all of the above groups with the exception of end-consumers. Their main customers are manufacturers of optical media, such as Technicolor, Ritek Global Media, Sonopress and MBI. Other important clients are Microsoft, EMI, Samsung, Warner, Infodisc, Cinram, Panasonic, MBI, DAI Nippon Printing, and CMC.
AudioDev’s clients can be found all over the world. The main markets being in Europe, USA and Asia. USA is the main market for pre-recorded DVDs. This is explained by the closeness to the manufacturers’ customers i.e. the music, film and gaming industries. Demands for CDs are declining since DVDs are expected to replace the importance of CDs in Europe and the USA. Test equipment for recordable and re-writable formats is mainly sold in Asia, the main market for manufacturing these discs (CD-R/RW and DVD-R/RW, DVD+R/RW).
It should be noted that AudioDev does not only develop and sell test machines, but also offers test services for companies who do not own test equipment yet who are concerned with disc manufacturing quality.
What’s driving the market?
The market for production equipment and, consequently, test equipment is driven by the fact that new optical formats are introduced at an increasingly rapid rate at the same time as the overall demand for optical media increases. Each new format increases the level of complexity, a fact that also applies to the development of existing formats. New, more complex formats mean that demand for advanced testing is growing.
Why testing?
Manufacturers of optical media and drives (the most important component in a CD or DVD player) are the two main groups using test equipment.
Manufacturers of optical media invest in test equipment to assure the stability of their production process and to make sure that their products meet a consistent level of quality.
Drive manufacturers invest in testing equipment to verify the compatibility between the disc and the drive. This is done to make sure that a disc can be put into any player worldwide and play or record without errors.
So what do we test?
A number of parameters are specified to ensure that the quality requirements for each CD and DVD format are satisfied. These parameters are monitored using test equipment.
There are various methods for testing optical media. AudioDev’s equipment performs signal tests, i.e. checks playability using a laser to follow the track. The signal test is the largest test segment, as this actually confirms playability.
The other two ways of testing are: scanning the surface to check whether the surface layer has any visual defects, and testing whether the right information has been transferred from the master disc to the replica.
To sum up: Testing equipment is used to make sure that any consumer can expect their newly bought disc to play in any player – it ensures playability. It is also used to give the manufacturers a verification of a stable production process. Finally, testing equipment is used to make sure that the discs meet industry standard – the closer to the industry standard, the better the quality. AudioDev’s products are the number one product on the market as they measure closest to the industry standard.
Test machine:
For this review we will be using a computer with the following configuration:
Hardware:
- Motherboard: ECS Elitegroup N2U400-A with Nvidia nForce 2 Ultra-400 and nForce MCP chipset.
- Processor: AMD Athlon XP 2800+ (Barton) 333 MHz FSB.
- RAM: 1 GB Infineon PC2700 DDR
- GFX: ATI Radeon 9600 XT
- Sound: SoundBlaster Audigy
- Hard disk: Samsung SP1614N 160 GB.
System set-up:
DMA (Direct Memory Access) and autorun was enabled for all the test drives:
- LITE-ON DVDRW SHOW-1633S
- Philips DVDR1640P
- PLEXTOR DVDR PX-712A
Software:
Windows XP professional is installed on the computer along with Service Pack 2. We will be using the following software in this article:
CATS limitations:
When testing disc or drive quality it is first important to realize that such tests do not deliver absolute values : a PI/PO plot always results from a combination of factors, which are a given media, a given drive and a set of operating conditions. Indeed, PI and PO errors are not values read from a disc like the book type or a logical sector number, but the result of a calculation performed by a DVD drive during a standard reading of the disc; for instance, CATS tools use either a Pulstec SDP1000 for the SA300 DVD Tester or a Philips CDM4 for the SA3 CD tester. This means that the errors reported by a CATS’ drive (or a PC drive) can not only differ from the ones reported by another consumer drive, but also from the ones reported by the same drive with another firmware, or by the exact same consumer drive at another time. Obviously, severe physical defects will always cause errors, but all errors are not caused by physical defects, and the same physical defect can cause different amounts of errors on different consumer drives. This is why you should never compare PI/PO plots obtained with different PC drives.
So what is the point of using a CATS device instead of a PC drive if the PI/PO errors it reports are not absolute values? First of all, CATS use well defined calibrated drives, which ensure that all the results obtained with a given model will be much more consistent: this makes comparisons much easier for big companies where tests are done on multiple sites. Multiple tests on the same disc are not only more consistent than with consumer drives, but also more accurate, since CATS architectures are specifically designed for disc scanning. Nowadays AudioDev is a recognized and well accepted reference in the optical storage world and CATS are used by about all drive manufacturers. But the main advantage of a CATS is that it reports many more information than an end user drive: on top of the usual PI/PO and jitter plots, a CATS measures about 50 other parameters like reflectivity, asymmetry, signal amplitude, etc. All these physical information are probably meaningless to end users, but they give good insight about the media and can be very useful for professionals to investigate the root causes of burning or playback problems.
We present in the following pages the results of a few discs we tested with both CATS (SA300 family with Pulstec SDP1000 drive) and various popular PC drives. When needed, the results of software measurement tools were scaled to match PI SUM8 and PIF SUM1. Values in between parenthesis denote partial results, which means that the disc could not be played until the end by the drive. The goal here is not to find out which media or drive is best (this would require many more tests), but just to compare the results we get.
Test Disc #1:
The first test disc is a Samsung DVD+R 4x media from Taiyo Yuden:
--------------------------------------------------------------------------
Unique Disc Identifier : [DVD+R:YUDEN000-T01-000]
--------------------------------------------------------------------------
Disc & Book Type : [DVD+R] - [DVD-ROM]
Manufacturer Name : [Taiyo Yuden Co. Ltd.]
Manufacturer ID : [YUDEN000]
Media Type ID : [T01]
Product Revision : [Not Specified]
Disc Application Code : [General Purpose]
Recording Speeds : [1x , 2.4x , 4x]
Blank Disc Capacity : [2,295,104 Sectors = 4,482.6MB = 4.38GB (4.70GB)]
--------------------------------------------------------------------------
** INFO : Hex Dump Of 'Media Code'-Block Listed Below
** INFO : 4-Byte Header Preceding 'Media Code'-Block Discarded
** INFO : Format 11h (Method 1) - ADIP Information
0000 : a1 0f 02 00 00 03 00 00 00 26 05 3f 00 00 00 00 .........&.?....
0010 : 00 00 01 59 55 44 45 4e 30 30 30 54 30 31 00 38 ...YUDEN000T01.8
0020 : 23 54 37 10 02 4e 72 02 9c 63 16 16 0b 0b 0a 0a #T7..Nr..c......
0030 : 01 19 1b 0b 0b 0e 0f 01 00 00 00 00 00 00 00 00 ................
0040 : 01 00 38 38 02 2c 63 20 08 30 22 10 00 20 20 01 ..88.,c .0".. .
0050 : 00 00 02 2c 63 20 08 30 22 10 00 20 20 01 00 00 ...,c .0".. ...
--------------------------------------------------------------------------
[ DVD Identifier - http://DVD.Identifier.CDfreaks.com ]
--------------------------------------------------------------------------
AudioDev CATS test results:
Disc id: DVD+R SAMSUNG
Disc Manufacturer ID: YUDEN000
Analysis of CATS results:
Most of the essential parameters are within the specification limit. The Reflectivity (R14H) is slightly lower than the minimum required value (45%) on the complete disc. The DC Jitter (time variations of Data versus the recovered Clock) and Bottom Jitter (Data to Clock Jitter tilt compensated in 3 points) show some peaks above the limit (9% for a DVD+R), but in average is still ok. Overall a good disc, which should not cause any problem.
Our home-made test results:
Scanned with KProbe and Lite-On SHOW-1633S
Scanned with CD-speed and Philips DVDR1640P
|
Drive Info |
|
ID:1 PLEXTOR DVDR PX-712A V1.05 (#101824) |
|
Test Settings |
|
Read Speed: |
2X CLV |
| |
|
Test Interval Length: |
High Accuracy |
|
Test Result |
|
Disc Info: |
CD_SPEED_DATA_TEST_B DVD-ROM, 4482 MB (CD_SPEED_DATA_TEST_B) |
| |
|
| |
Avg |
Max |
Total |
|
|
PIE |
0.03 |
6 |
3992 |
|
|
POF |
- |
- |
0 |
|
| | |
|
Test Duration |
|
0:28:19 |
|
Drive Info |
|
ID:1 PLEXTOR DVDR PX-712A V1.05 (#101824) |
|
Test Settings |
|
Read Speed: |
2X CLV |
|
Test Result |
|
Disc Info: |
CD_SPEED_DATA_TEST_B DVD-ROM, 4482 MB (CD_SPEED_DATA_TEST_B) |
| |
|
|
|
|
Test Duration |
|
0:28:38 |
|
Summary:
|
Comparison
Results |
Average
PIE
sum 8 |
Max
PIE
sum 8 |
Average
PIF
sum 1 |
Max
PIF
sum 1 |
POF |
|
AudioDev
CATS |
2.1 |
30 |
0 |
3 |
0 |
|
Lite-On
K-Probe |
0.19 |
6 |
0 |
1 |
- |
|
Philips
CD-Speed |
0.94 |
7 |
0 |
- |
0 |
|
Plextor
Plextools |
0.03 |
6 |
- |
- |
0 |
CATS vs. drives results:
The results obtained by the drives and the CATS are remarkably consistent, as seen in the summary table. The only difference is that the CATS showed a few spikes at the beginning of the disc (bump of PI errors which follows a peak of DC jitter), while the PI errors plots from the drives are all flat. Note also that although the jitter plots from the CATS and the Plextor drive match, the one from the Philips drive is remarkably flat (and slightly higher than the two others). This suggests that the CATS could be more sensitive to jitter variations (which can be caused by a bad precision of pits or lands) than the Plextor drive, but we will need to get a confirmation from other discs. Apart from this, PI/PO plots are low, which confirms that this is a very good disc.
关于2-6碟片测试放在另一篇文章中，放在一起实在是太长，不方便阅读。不过，总结还是要在这里贴出来的。
。。。。。。此处省略 第2至6组碟片测试。
如有兴趣，请访问该链接：/kb/KB265-200573.html
Conclusion:
As demonstrated by these few tests, anything can happen: sometimes the CATS and the drives agree and sometimes they disagree, sometimes the CATS can read a disc while the drives fail and sometimes it’s the other way around. And the worse the quality of a disc is, the more differences you will likely see between all test results.
But as explained before, this is perfectly normal, since PI/PO plots not only show media quality but also the efforts of a drive to play a given disc: for instance, if a drive has very good mechanical and optical parts you will get fewer errors but if it uses cheap parts you will get more errors, all this with the same disc.
To summarize the differences we saw between CATS and drive measures, let’s define 3 terms:
- Consistency illustrates the deviation obtained by multiple tests on the same disc with a given testing device. CATS are more consistent than drives because the results are repeatable, and several CATS machines will also give more consistent results than several drives of the same brand/model.
- Accuracy corresponds to the precision of the measurement system. For instance, on disc 6 KProbe reports a PIF of 209 (which should actually be 208) and on disc 4 CDSpeed reports a PIE SUM8 of 2360. The measurement accuracy of CATS is higher than the one of drives, because they are specifically designed to be measurement tools, while the alternative are software tools and consumer drives running on a PC architecture. For instance sampling errors, bus lags, driver conflicts are not problems which will disturb CATS measurements. Furthermore, the hardware parts of the CATS are precisely calibrated to match the measuring requirements defined in the DVD-ROM specification, which also contributes to its higher accuracy.
- Correctness is something absurd, which corresponds to a popular idea that each ECC block of a disc contains a precise number of PI/PO errors, and that measurement tools try to find out this absolute value. Let’s repeat it one more time: PI/PO errors are not on a disc. PI/PO errors are the result of a calculation and they depend not only on the disc but also on the drive and on many other physical parameters, thus no PI/PO value is more correct than another. Just like PC drives, CATS will show slightly different results each time you run a test on the same disc, and none of them is wrong : they just correspond to what the error correction block calculated at that particular time.
CATS machines are definitely very useful for professionals, because they give a lot of technical information and can perform more accurate and consistent measures than consumer drives. On the other hand, CATS machines still use drives and limits defined in the original 1996 DVD-ROM specification, thus as time passes its reports differ more and more from the performances that modern drives can achieve, as illustrated by disc #4. Therefore what should matter to an end user are the tests he does by himself, with his own drives and his own media, in the recording and playback conditions he plans to use. And if you choose carefully the media and recording speeds which are best for your burner, you have a good chance to increase the compatibility and lifetime of your discs, which are the final goal of testing.
//转载请注明出处，
DVD知识库/.2401087，
http://www.dvdfaq.com.cn
