Thanks to Jan and Cameron for their detailed responses to my questions so far.
At 12:49 -0400 2002/07/12, Jan E. Schotsman wrote: >A faster processor will not get you better better video capture. The bottleneck is >hard disk (speed and size) and ultimately the PCI bus. If you want to digitize >uncompressed VHS (I would suggest 480x320) you need to capture 9.2 MB per second. >That is only possible with a fast hard disk (UltraSCSI or better or a new ATA disk). I don't want to save videos in uncompressed form. I would quickly run out of disk space if I did. I do want to save them in a compressed form that can be uncompressed without significant loss of quality. (The original tapes, where important, would be saved for later use if needed.) I'm presuming that a fast hard disk would not be necessary if the video were reasonably compressed. >I am not sure about the Quadra (what hard disk did it come with?). I was referring to a generic 840av, not a particular instance of same. >The PowerMac 7500-8600 are unmatched as far as uncompressed video capture is >concerned (all the way up to 576x768!). Does that mean that their A/V modules can transmit full NTSC (or even PAL) video to the CPU? If so, couldn't a fast-enough CPU compress the signal and write it to disk? At 06:27 -0700 2002/07/11, Cameron Kaiser wrote: >At least in my experience, the bottleneck seems not to be the CPU. Even with a G3/500 >in my 7300 and a ProTV capture device, not even 320x240 could be captured reliably at >full NTSC frame rates. I don't believe the 7500-7600 AV inputs have hardware >compression either, so the same applies. > >Even if you could capture 320x240 at full frame rate (29.97fps for NTSC), the problem >is that 320x240 video is typically not interlaced. Again, I don't know for sure if >the 75-7600 AV inputs spit out an interlaced signal, but neither my Fuse nor my ProTV >emitted interlaced video at 320x240. Instead they put out single-frame video which >compressed fine and played okay in QuickTime but when encoded into MPEG-1 stuttered >and artifacted on both the VCD units I tried it on. > >To force interlacing, you need to boost up to 640x480 resolution @ 29.97fps, and I >know the 75-7600 AV isn't up to this task, no matter how fast the CPU. Apparently, Cameron's opinion of the A/V modules is lower than Jan's. Are there specs on what these A/V modules can do? >You'll need something that can do realtime compression, which the Aurora Fuse and >related products feature (it supports on-the-fly Motion JPEG A), which means the CPU >can devote full attention to storing the video and capture at full rates in real-time. > > > 2) Can't one 'embed' a low-resolution, low-rate, source in a > > higher-resolution, higher-rate format? Of course, the quality would be low, > > but maybe it wouldn't matter if the source were just 'talking heads'. > >This depends on the player. My Toshiba DVD/VCD will balk at anything that isn't NTSC >frame rate interlaced video. If you're making a disc designed to play anywhere you >go, best not take chances on the capabilities of the playback unit. QuickTime Player >and MacVCD (which is based on QT's MPEG-1 playback code) seem to accept weird frame >rates, but I can't guarantee that the Apple DVD player will since I haven't tried >making DVDs yet. What I meant by 'embed' is convert to the better format in the same way that one can convert VHS to NTSC. (If that hadn't been possible, we never would have seen the Rodney King video on TV!) Of course, the visual quality would be, at best, that of the low-rate, low-resolution original. >The bottom line is, I wouldn't trust it if this video will ever be for more >than personal use. As I said above, the originals would be saved. Right now, I'm mainly interested in (1) learning and (2) putting some video on the internet. - Aaron P.S. I also have -- somewhere (;-<) -- an ixTV card from, IIRC, Orange Micro. Aside from handling composite and broadcast input, can it do anything that the A/V modules can't do? -- PCI-PowerMacs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | -- Sonnet & PowerLogix Upgrades - start at $169 | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> PCI-PowerMacs list info: <http://lowendmac.com/lists/pci-powermacs.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive:<http://www.mail-archive.com/pci-powermacs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
