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DVD-9 Compatibility

Creating a Suitable Master for Replication By Craig Elliott Hanna

With the advent of inexpensive desktop DVD authoring applications, it's now possible for almost anyone to make a DVD on their MAC or PC. And with replication facilities accepting recordable DVDs as masters, the workflow has become even easier and more streamlined than in the past. But just because you can make a DVD that plays on your computer or set top DVD player at home, doesn't mean when you replicate and distribute your DVD it will work correctly or play on most or a majority of DVD players. No DVD is 100% compatible, but there are certain things you can do to help increase the compatibility of your final DVD.

There are many types of DVDs, the most popular being the DVD-5 and the DVD-9. These two types of DVDs would encompass the majority of Standard Definition DVDs you buy and rent. The main difference between the two is the amount of data or information each can contain. A DVD-5 can hold up to 4.7 GB (Gigabytes) of data as compared to a DVD-9, which can hold up to 8.4GB. This roughly translates into 2 hours and 4 hours of video respectively. The second difference between the two is the physical makeup of the disc.

The DVD-5 is a single layer disc (one layer of data) vs. the DVD-9, which is a dual layer disc. The bottom layer of the DVD-9 is referred to as Layer 0 and is read first. The top layer is referred to as layer 1 and is read last. Layer 0 is a semi-transparent layer, which allows the DVD laser to read through it and acquire the data on layer 1.

Region coding and copy protection on recordable DVDs
Region code information and copy protection information is contained within the lead-in of the DVD disc. With recordable DVDs and DLs, this lead-in is prewritten and cannot be changed. Therefore, any copy protection flags you turn on or region codes you assign in your authoring software will not be recorded to disc. To retain this information, you must submit your master on DLT or DDP on Disc. Talk to your manufacturer about submission guidelines for DLTs and DDPs on disc as master requirements vary. Note: by default recordable DVDs and DLs play in all regions. If you want to make your DVD region specific, again, you must supply DLTs or DDP on disc.
When reading a DVD-5, the DVD player's laser always starts at the inside (center) of the disc and reads outward. On a DVD-9, as with the 5, the laser will always read inside out for layer 0 (the bottom layer). But since there are 2 layers on the 9, when finished reading layer 0 the laser must readjust its depth to read layer 1 (referred to as the layer break). Unlike with layer 0, the DVD author, or programmer, can control which direction the laser will read layer 1. OTP (Opposite Track Path) the laser acquires layer 1 and reads from the outside edge of the disc towards the inside. PTP (Parallel Track Path) reads layer 1 in the same direction as, or parallel to, layer 0 from the inside out. The former is more preferable because it results in a shorter pause at the layer break. The pause is shorter because with PTP the laser has to retrace back to the center of the disc in order to start reading layer1. With OTP, the laser is already at the outside edge of the disc and can then adjust depth and begin reading layer 1 relatively quickly. Most likely you have seen the layer break and not known it. The next time you rent a DVD from Blockbuster or Netflix, watch for a point during the movie where the video pauses for a second or two and them resumes playing. This will usually occur at the beginning or end of a scene to make it less noticeable for the viewer.

Creating a DVD with maximum compatibility involves more than just building your DVD and burning it to a DVD-(+)R. This is especially true when creating a DVD-9 master. The outside edge of a DVD disc is the most difficult part for the DVD player to read. For this reason the DVD Specification, which outlines rigorous standards for Data on and the physical makeup of DVD discs, specifies how far towards the outer edge of the disc data can be written. The exact specification is 58mm from the inside of the disc (or a 58mm radius). Any data written outside the 58mm radius may cause the DVD to skip, stutter, or not play beyond that point. When supplying a DLT tape or DDP on DVD master, this is not an issue, because you can control where the layer break occurs. However, supplying your master on a DVD-+(-)DL can be problematic. Originally the DVD-DL conformed to the 58mm radius specification. However, in an attempt to put more data on a DVD-DL, manufacturers have pushed beyond the 58mm restrictions and allow data to be written further towards the edge of the disc. This may result in a disc that fails due to the aforementioned issues.

So how do you ensure this won't happen? The absolute best method for supplying a DVD-9 master to your replicator is on 2 DLT tapes (1 tape per layer) or DDPs on 2 DVD-R 5s. DLT tapes contain DDP (Data Description Protocol) files, a file format utilized by disc manufacturers to make a glass master. The DDP contains all the assets and information about the DVD including *region codes, copy protection, and layer break information something a DVD-DL will not contain. *(Read the above sidebar on Region codes and copy protection on recordable DVDs). DVD authoring applications may have the ability to write to DLT tapes but requires purchasing a DLT machine. There are limitations to the type of machine and tape a replicator will accept. Best practice is to always call and find out their specific requirements. If you do not want to go the route of a DLT, with DVD Studio Pro you can write DDP files to DVD+(-) R discs. These DDPs are the same files you would write to a DLT. As with a DLT, a DVD-9 will require 2 DDPs on Discs one for each layer. Check with your replicator to see if they accept DDPs on disc and for their specific submission requirements.

Another but somewhat less reliable way to supply your DVD-9 master is on a DVD+(-)DL. Previously the only way to submit a DVD-9 master to a replication facility was on a DLT (Digital Linear Tape). But within the past few years, facilities have been accepting Dual layer recordable DVDs. These discs may or may not produce a suitable master. It's important to understand that layer break information formatted in programs such as DVD Studio Pro do not carry over when burned to a DVD-DL (unlike with DDPs). The layer break is controlled by whatever disc burning software you use. Some programs will let you set the layer break and others will simply write to layer 0 until it is filled, then writes the remaining data to layer 1. This may result in data being written outside of the 58mm radius limitation leading to disc failure. If you have burning software that will let you set the layer break, you will need to calculate where the break will happen. For OTP DVDs layer 0 needs to be filled. This translates to 2,085,472 sectors or approx 4.07 GB. Placing the layer break beyond this point will result in violating the 58mm radius limitation.

If you cannot supply DLTs or DDPs on Disc, or don t have software that will let you control the layer break, the only other way is to supply your DVD-9 master is on a DVD+R DL disc (not a DVD "R DL). Through testing, we have discovered that some DVD-DL discs allow data to be written outside the 58mm radius. However, at the time of this writing, we have found that DVD+R DL discs are more reliable than DVD-Rs and keep data within 58mm radius limitation. *(manufacturer s product is subject to change and may in the future no be reliable as a DVD-9 master format. Testing on your part is required and Disc Makers holds no responsibility for any manufacturers recordable media, masters submitted on DVD-DL media, and Layer Break placement.) So, if you have no other option, try submitting your master on a DVD+R DL. You won t have control over where the layer break falls, but you may be able to keep data within the 58mm radius limitation.

If you want to ensure your DVD-9 will be within the DVD specification and want precise control over the layer break, the only sure-fire way to do this is with DDPs on DLTs or DDPs on DVDs. If you must submit your master on a DVD+(-)R, follow the guidelines presented in this article and you will increase your odds that your project will be a success. As always, before sending your master in, test it on as many DVD players as possible to make sure it performs the way you expect it to.

For more information visit the Authoring House at Disc Makers at http://www.discmakers.com/authoring/

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Related Keywords:DVD authoring, DVD-9, DVD-5, DVD authoring applications, Region coding and copy protection on recordable DVDs

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