Apple gives QuickTime new version number
Promises speed, security
Updated Apple has released an upgrade to both the Mac and PC versions of its QuickTime media software, promising better performance and tighter security.
Regarding performance , Apple says that the upgrade to version 7.6 improves single-pass H.264 encoding quality and AAC encoding fidelity, increases the playback reliability of Motion JPEG media, fixes problems with the consistency of exporting audio tracks of MPEG videos, and improves compatibility with Apple's iChat and Photo Booth applications.
The Windows-only security improvement covers Vista, XP SP2, and XP SP3, and it updates the QuickTime MPEG-2 Playback Component for Windows to fix a vuln in which "a maliciously crafted movie file may lead to an unexpected application termination or arbitrary code execution." Details of the update and how to determine if your system needs it can be found here .
The security improvements that add Macs to the mix extend coverage to Mac OS 10.4.9-11 and 10.5.x and cover a broad range of maliciousness. Details can be found here .
Mac users can install the upgrade through Software Update (be prepared for a reboot). Alternatively, the 63MB Mac OS 10.4 download can be found here  and the 72MB 10.5 download here . The 20MB Windows download can be found here .
You might want to hold off on updating to QuickTime 7.6. Although we experienced no problems after updating to 7.6 on a small number of Macs, we may have been lucky.
According to a report  today on MacFixIt, "Users are experiencing a few issues with the new update, including problems with third-party codecs and more." The "more" includes problems with the Finder, games, and audio export.
The good folks at MacFixIt offer solutions to some of the problems, such as disabling third-party codecs.
We'll follow this latest cock-up as it develops. ®