Philips PCA635VC D e o P l ay b a c k O p t i m i z a t i o n, Parallel Port Recommendations

Parallel Port Recommendations

The parallel port is the first contact a computer system has with the video information using the Philips PCA635VC. You can have the fastest hard drive, hard drive controller, computer processor and RAM and still not see an improvement in video capture if the video originated at a slow Parallel Port. We strongly recommend that you use a fast parallel port con- nection when optimizing a system for video capture.

At the time this manual was created, there are 3 common types of parallel ports available in systems- Uni-directional, Bi- directional and the one we strongly recommend, ECP. Some systems have the ability to offer multiple parallel port options through the system’s Bios Setup. Here an advanced computer user can tell the system that the on-board (built into mother- board) parallel port to utilize the ECP standard instead of Uni-directional or Bi-directional. It should also be noted that some systems do not have an on-board parallel port, rather they have a separate card that occupies a slot in the system. In which case, it may be advantageous to upgrade the system to one with an ECP parallel port. This could be done with a stand-alone card (preferably PCI based) or new motherboard.

Processor, Hard Disk & Controller Recommendations

After the video passes through the parallel port it is handled by the system processor and forwarded to the hard disk and controller. All of today’s multimedia applications require fast processors. We recommend using at least a Pentium 75 when working with video or any multimedia applications. The hard disk and hard disk controller will provide for additional frame rate capture ability over just using an ECP parallel port (described earlier). Before you buy your next “Video” hard drive, contact the prospective hard drive manufacturers and tell them to give you the SUSTAINED DATA TRANSFER RATE for the hard drive. The higher the value in megabytes, the better your video and audio capture performance will be.

Most of today’s hard disks and controllers are compatible with ATA mode 3 or 4. ATA mode 3 implies a transfer rate of 11MB/second and ATA mode 4 implies a transfer rate of 16MB/second. HOWEVER, THIS ONLY REFLECTS THE TRANSFER RATE TO AND FROM THE HARD DISK BUFFER (AKA: CACHE) AND DOES NOT INDICATE THE ACTUAL SUSTAINED DATA TRANSFER RATE. Simply stated, the sustained data transfer rate is what informa- tion transfer is maintained 100 % of the time. Very few hard drive manufactures even list the sustained data transfer rate in their specifications. This is probably because it’s more impressive to say that they have a 16MB/second transfer rate instead of less than 1MB/second sustained.

Disable the system’s WRITE CACHE. This will improve the capture performance. In addition, your system’s WRITE CACHE settings may need to be adjusted if you are using a fast system with a fast hard drive and hard drive controller. More specifically, you may try disabling the write cache altogether in the operating system bios and hard drive controller setup. In most other situations write cache is desirable, however, when capturing video this buffer is not large enough and only inhibits video transfer to the hard drive by writing information later and then trying to catch up later.

De-fragment your hard drive often to optimize video/sound capture performance. Do you already have a fast hard drive and controller? There is a way to further optimize your hard drive performance. It’s called de-fragmenting your hard drive. There is a hard disk de-fragment utility built into Windows 95 and a number of system “first aid” software packages con- tain this as well. De-fragmenting your hard drive will keep all the video in one location, this way the hard drive doesn’t spend all of its time looking for a place to put video during capture.

V i d e o P l ay b a c k O p t i m i z a t i o n

Video files, in general, play better on newer multimedia computer systems and Videograms run better than standard video files, thanks to the compression. Our first recommendation when playing back video is to make sure you’re playing back Videograms which can be self-running (.EXE) or (.VGM). For further optimization we’ll need to look at the computer system again. As with video capture, playing video requires the video information to flow through the computer system (shown below).

When Playing Back Video

The following is an outline of the video playback process

1Computer’s Processor Requests Video from Hard Drive Controller

2Hard Drive Controller Requests Video from Hard Drive

3Hard Drive Sends Video to Hard Drive Controller

4Hard Drive Controller Sends Video through System Bus to the video card

40