Optical Platform Changes in Windows 8
This article describes the new features and changes in the Optical Platform for Windows 8.
The Optical Platform in Windows 8 continues comprehensive support for optical disc media types and includes two important new features. The Zero Power Optical Disc Drive (ZPODD) feature is added as well as support for optical disc drive asynchronous notification. Also included, are improvements in image mastering and device request handling.
For changes in Windows 8 related to playing digital media, please refer to Making Windows Media Center available in Windows 8 and FAQ - DVD playback and Windows Media Center in Windows 8.
Media Types in Windows 8
Writing to the common optical disc formats is supported in Windows 8. As in Windows 7, users can continue to choose between Mastered and Live File System (Live FS) modes for optical disc burning. The various scenarios for choosing which mode to use, Mastered or Live FS, are described in Which CD or DVD format should I use?
All of the media types supported in Windows 7 are available in Windows 8. The following media types are supported.
- DVD-R Dual Layer
- DVD+R Dual Layer
Note: Windows RT only supports reading from optical discs, not writing.
Zero Power Optical Disk Drive
Zero Power Optical Disk Drive (Zero Power ODD or ZPODD) is one of many new Windows 8 features introduced for power efficiency. On a system enabled with ZPODD, when Windows 8 detects that there is no media in an optical drive, power to the optical drive is cut off. As soon as the user attempts to use the optical drive, power to the optical drive automatically resumes and the user will be able to use the optical drive immediately, unaware that the power to the device was ever turned off. Everything happens in the background and normal user interaction is not affected. ZPODD applies only to optical drives that use the slimline SATA connector and is typically found on laptops. Some servers and desktops also use a slimline SATA connector for optical drives.
In order for ZPODD to work, the ZPODD feature must be supported by the optical drive, the motherboard, and the BIOS. The ZPODD Platform and Driver Design Guidelines for Windows 8 whitepaper lists all the requirements necessary to enable ZPODD on Windows 8.
Support for Asynchronous Notification
In Windows 7, the CD-ROM driver polls the optical drive every second to check if media status has changed (a disc was inserted or removed). This has a negative impact on power efficiency. So, in Windows 8, the CD-ROM driver receives notification of media status, using the Asynchronous Notification feature, from the optical drive. The CD-ROM driver no longer polls the device if both the port/miniport driver and the optical drive support Asynchronous Notification. Instead, the optical drive will fire an interrupt when media status changes, and only at that time will the CD-ROM driver query for media status. This makes the media detection logic far more efficient. A Virtual Optical Drive created by Windows when an ISO is mounted also supports Asynchronous Notification.
Improvements in the Optical Platform for Windows 8
Important changes and bug fixes for the Image Mastering API and the CD-ROM class driver appear in Windows 8. Improvements were made in Image Mastering API (IMAPI) 2.0 to stage and burn images to optical media, and in the CD-ROM class driver. These improvements are highlighted here.
- IMAPI 2.0 changes in Windows 8
- IMAPI 2.0 now correctly calculates the size of writable area on BD-R media and uses correct command to detect available writable blocks on BD-R.
- Data over flow during BD media write verification is fixed.
- CD-ROM Class Driver (Cdrom.sys) changes in Windows 8
- In Windows 8, if a request is taking a long time, requests backlogged in the queue can be successfully cancelled if the owner thread exits.
- Command execution timeout value is reduced from 260 seconds to 20 seconds for the following commands: TEST UNIT READY, GET PERFORMANCE, and READ CAPACITY. This change will reduce 0x9F bug check on faulty ODDs that don’t respond to these commands within a reasonable time.