AGrin
Advanced Member | Редактировать | Профиль | Сообщение | Цитировать | Сообщить модератору
While we praised the Matrox G400 for its DVDMax function, going from Matrox's
software DVD to ATI's hardware accelerated MPEG2/DVD decoding, we noticed a
world of difference not only in performance but in image quality, as well.
Like the Rage 128, the Rage 128 Pro provides for hardware motion compensation,
an industry "buzzwords," -- what does it mean? The amount of CPU power required
to decode a scene varies from one scene to the next. While a one system
configuration will have no problems decoding a few scenes once the complexity of
the decoding increases (ATI gave the example of an interlaced music video at 60
fields per second versus 24 fps for film) that same system may exhibit a
significant drop in frame rate during these complex decoding processes and will
thus produce jerky playback.
Hardware motion compensation takes this into account and helps provide playback
at 100% speed without resorting to dropping frames or reducing quality in order
to reduce CPU load. While hardware accelerated motion compensation does not take
the place of a hardware MPEG2/DVD decoder it does aid systems in the playback of
MPEG2/DVD video sources.
The hardware accelerated motion compensation of the Rage 128 Pro does aid
quality considerably. It helped produce a very smooth picture that is superior
to any software-only solution and was closer to the level of our own set top DVD
solution.
The second point of hardware supplemented DVD decoding the Rage 128 Pro brings
to the table is its support for Inverse Discrete Cosine Transform (ICDT) in
hardware. ICDT is just a part of the MPEG2 decoding process and by offloading it
onto the graphics card from the CPU, your CPU is freed up to perform other
tasks. Not only does this help users with slower CPUs but it also makes
multitasking more of a reality while playing a DVD on your computer.
While we're still not at the point where you can run a primarily software
decoded MPEG2/DVD stream and play a game of Quake 3 in the background,
offloading ICDT onto your graphics chip does help keep the frame rate up during
the decoding process even while you surf the net or launch Word.
The third and final point on the Rage 128 Pro's DVD decoding capabilities is its
ability to perform the DVD subpicture feature in hardware. DVD subpicture is a
very commonly used feature that allows you to display graphics over video such
as subtitles or menu features, both of which are commonly used in DVD movies.
In order to place a subpicture over a DVD stream, the subpicture (a compressed
bitmap) is decompressed and outputted to the screen on the fly. While this isn't
the most CPU intensive part of playing back a DVD, it does contribute to some of
the CPU load associated with DVD playback where there is excessive use of the
subpicture feature. Performing this in hardware allows for the decompression of
the subpicture on the fly as it sends it to the DAC for output. This only
reduces memory bandwidth and CPU utilization by a small percentage but it does
help.
Although this sounds great on paper, the fact of the matter is that this feature
won't really be used all that much since subpictures are not commonly used in
most DVD playback situations. However, it is a nice feature to have and that
tops off the trio of hardware DVD acceleration features the Rage 128 Pro
supports.
|
Всего записей: 775 | Зарегистр. 14-09-2006 | Отправлено: 19:00 29-11-2014 | Исправлено: AGrin, 19:01 29-11-2014 |
|
