CompuServe Thread

A visitor (he is making a similar board but has not success yet) came to our company, while chatting, he told us that this board is in that pre-release status for some months. So, figure it out by yourself. BTW, a fast capture board only solve less than half of the problem of capturing (digitizing) video to your hard disk. The hardware bandwidth of the storage device, disk controller, and the bus connecting them determine the rest. I know you must know this, however, it may help the others in the forum to understand the problem and solution better. So, I write them down at the following. To achieve non-dropping frame capturing with best quality, you need a perfect match (and compromise) of all of them. A capture board can easily capture faster than the storage device can take. For the cards for lower speed buses, like miro DC1 is on ISA bus, this is more severe. That is because even the hard disk can do more, the bus itself has a practical bandwidth up to around 1M bytes per second. EISA or PCI bus with Fast SCSI-II hard drive has a higher but not so high practical limitation, too. Basically, there are two ways to work around this. Either it will compress more (in turn, lower the quality of the video captured) to use standard storage device (and bus) or it will use proprietary fast storage device to preserve the video quality. Boards just as miro DC1 choose the former approach (up to 1:35 compression rate), so that it can be plug-and-play into almost any PC that you can find. When I work with it on a Pentium/90 machine with a PCI Fast SCSI-II AV drive and host adapter, I got VHS to sub-VHS class video result and play it on TV in real time. I'm quite happy with it. If I remember them correctly, some use boards like Targa 2000 (around 1:2 to 1:5 compression) to compress and controll the hard disk directly while others use a similar board (around 1:3 to 1:8 compression) with two Fast/Wide SCSI-II disks link in parallel. If work right, they can give you VHS or semi S-VHS output, but either you need to buy the whole set from them or use a certified hard disk and card that they approved. You will need an AV class hard disk which can maintain a suitable transferring rate even there are fragments in the disk clusters. Adding disk cache may even slow the capturing process down. This is because you need to put the data into the physical disk surface as fast as it can, disk cache will not help. If you have many many RAM, capture video directly to RAM or use that as a RAM disk and capture video to that disk will help you to capture small clips better. Of couse, some systems offer you another option, online editing, which will use computer only to controll the analog devices connected and do the editing just like using traditional equipments.