Date: Mon, 17 Apr 1995 10:04:48 -0800 From: "Zavatone, Alex*" <azavatone@MACROMEDIA.COM> Subject: Fastest playback of QTRoy Pardi and Marvyn wrote that a QT plays back fastest the second time. Yup sure does since it has been loaded into memory. Soo to make it playback fast on the first time, enable the preload to ram checkbox and preload the movie. You may also want to set the preloadRamSize for the QT (read the docs).
What Preload to ram does on the mac and on the pc are rather different. On the mac, the QT header is preloaded and as much of the moov is loaded into ram as set by the preloadRamSize. The head of the cd drive is also positioned at the start of the movie so there is no gap in loading any info that comes next. In cast you only loaded the first half of the moov and the rest will be streamed from disk.
On the pc, the code in the QT dll and in the Video for winders dll to preload DOES NOT EXIST. Taint our fault, it just isn't there. So all that is done on a preload is to position the drive's head at the start of the movie so there is no pause when the movie starts.
You must also take in to consideration, the amount of throughput you can get. Are you trying to load a 300Kps movie off cd? HAH! You're kidding yourself. The best throughput I've seen is off a mac 7100 cd with 263 kps. You probably will need to experiment to get the max throughput allowed. NOTE that different cd drives and drivers have different throughputs. If you want to get the actual throughput you can use my memmon tool to preload a series of cast members of a known size and use the timing feature in memmon to tell you the K per second. Memmon is available on Terry's Mediabook CD, on the Interactive buttons and controls CD and probably on Marvyn's site.
The summary is that there is a lot to consider when getting video to play as fast as possible off any media. Hope this helps.
Alex Zavatone
MacroMedia
AZavatone@MacroMedia.com