13 jun. 2005

HDV@Work#1 New codec from APPLE

HDV@Work#1: "HDV@Work

Jun 13, 2005 3:45 PM

What is H.264 Encoding?
Steve Mullen

Those shooting HDV are desperately looking for solutions that allow them to distribute HD productions. We have months to wait for Blu-ray, so folks have been using D-VHS and Windows Media 9. The other formats one that has been waiting in the wings is MPEG-4.
Until Apple introduced H.264 in QuickTime Pro and FCP 5, most of us did not need to understand MPEG-4. MPEG-4 H.264 (AVC) is MPEG-2 on steroids. Like WM9, it is a very bit-efficient codec. There are many new concepts that enable H.264 to be more bit-efficient.
H.264 benefits from increased precision in motion estimation, which is the key process of reducing redundant data across a series of frames. By expressing information to 1/4-pixel resolution as opposed to 1/2-pixel resolution as do most other codecs, H.264 represents both fast- and slow-moving scenes more precisely. Thus, objects in motion are more crisply reconstructed during decode, providing a better representation of the source material.
During motion estimation, other codecs process frames at the macroblock level (16 pixels by 16 pixels). H.264 can process segments within a macroblock that can range in size from 16x16 to 4x4, which helps encode complex motion in areas of high detail. "