Why does my PowerBook hard drive spin-down while recording a movie?
We recently isolated the problem of the premature spin-down on PowerBook hard drives when running QuickMovie to Apple's Built-In microphone driver. The problem does not occur in QuickPICT, and won't occur in QuickMovie if the QuickCam microphone is selected. It will also happen in Apple's MovieRecorder (so long as the Built-In mic is selected) and so is definitely not caused in any way by the QuickMovie application.
Apple's ROM code spins down the hard drive when recording sound from the Built-In microphone in order to minimize noise in the recording (the microphone is very close to the hard disk on many PowerBooks) - this works fine for recording short sounds directly into RAM (like when recording an alert sound), but not so well when recording long files to the hard drive (like with QuickTime movies).
Why am I having problems with QuickTime audio playback?
We've been tracking a bug in QuickTime which causes some problems when recording audio using the Built-In microphone driver. Basically, whenever the Built-In mic is the selected sound input device, sound output doesn't work. The way to check for this problem is as follows:
1) Record a movie using the Built-In mic as the sound input device.
2) Before playing back the movie, switch the sound input device to
QuickCam mic.
3) Switch to playback mode, and play the movie.
If the sound works correctly, you are experiencing the QuickTime bug. Unfortunately, this problem is not specific to Connectix software (it can happen with any QuickTime software) so it's unclear whether we can address the problem at all. The real fix will have to come from Apple, but, in the meantime, you can use the work-around outlined above to get sound playback to work.
Why doesn't QuickCam work on my PowerBook 5xx?
QuickCam draws its power from the serial port. The 100-series and Duo 200-series PowerBooks power QuickCam without problem. Most 500-series PowerBooks deliver enough power for QuickCam, as well. Unfortunately, some PowerBook/QuickCam combinations do not work. This is due to variations in parts tolerances on the PowerBooks and, to a lesser extent, QuickCam. Typical symptoms of power deficiency are either an entirely black display in QuickMovie or QuickPICT, or pictures that appear only intermittently. There is a way to supply enough power to make QuickCam work, even on PowerBooks with marginal power. Connectix manufactures a jumper cable that uses power from the ADB port to power QuickCam - the ADB port has much more power than the serial port, and was designed to power multiple devices. Registered owners of QuickCam with PowerBooks that do not supply enough power may obtain this cable for the nominal shipping and handling charge of $9.95. To order, contact Connectix Technical Support:
Phone: 800/950-5880 (North America)
415/571-5100 (International)
Fax: 415/571-5195
Electronic:
75300,1546 (CompuServe)
Connectix (America Online)
Connectix.TS (AppleLink)
RAM Doubler (eWorld)
support@connectix.com (Internet)
When you contact Connectix Technical Support, please provide the following information:
• Your name and phone number
• QuickCam registration number (for shipping address and confirmation of
registration)
• Credit card number and expiration date.
Currently, our fulfillment time on these cables is around 10 days.
Why doesn't QuickCam work on my Quadra 605/Performa 475/LC 475/Performa 575/Performa 578?
The QuickCam software "clocks" the serial port of your Macintosh externally. The software also determines the maximum throughput the serial port can handle and sets the communications speed between computer and camera to this maximum. On some Quadra 605-based machines, the Mac's serial port does not behave the way our software expects. This behavior appears to be due to part variations in the serial port oscillator crystal on the motherboard of these Macs, which handles the external clocking of the port. The end result is that QuickCam does not work on machines with these oscillators. (Note: we have only seen this problem on Quadra 605, Performa/LC 475, and a few Performa/LC 575 motherboards - no other Macintosh model exhibits this problem.) Typical symptoms of this problem are a few lines of video at the top of a QuickMovie or QuickPICT window, but an otherwise empty display. We finally managed to obtain several of 605 and 475 variants that exhibit the problem (our initial testing on over a dozen of these machines did not reveal the problem, as they had a different oscillator chip in them). We now have a solution for owners of these machines. The new QuickCam software on this disk contains this fix; when the new drivers detect that the port is not capable of handling our typical ~2 Mbit/sec maximum transfer rate, they drop communications speed to a lower rate that the port can handle.
What are the Requirements for an A/B Switchbox?
Using an A/B switch box will not damage QuickCam (we use them quite a bit at Connectix). However, the switch box needs to meet certain specifications:
1) It must be a mechanical, not electronic, switch (because QuickCam is
powered by the serial port).
2) It must switch all 8 pins.
3) It must use pass-through, rather than modem, cabling (modem cables
switch pins 1 & 2 with pins 7 & 8).
4) The total cable length, including the 5' QuickCam cable, should not
exceed 12' (once again, since QuickCam is powered by the serial port).
Why Isn't QuickMovie native on Power Macs?
QuickMovie is not the bottleneck; it's just "glue" between QuickTime and the movie file. There is actually very little processing going on in QuickMovie, and the processing that does occur is highly optimized - it spends most of its time waiting for data. The real speed limitations are
• brightness setting
• serial port throughput
• storage volume speed
• QuickTime (especially if you are compressing during recording)
• other factors (like whether virtual memory is on).
Adjusting the brightness changes the virtual "shutter speed" of QuickCam (the delay before it finishes integrating the image); more light will allow a lower brightness setting and therefore a higher frame rate. Since the bandwidth of the serial port is fixed, using the Mac's built-in microphone will increase the frame rate of the video (since, in that case, they're sent over different buses). On a PowerMac, it's important to use the "QuickTime PowerPlug" (which makes QuickTime mostly native), since that's a big bottleneck. Also, post-compression (as opposed to compression while recording) will allow a higher frame rate, as will recording to a RAM disk. Virtual memory can cause the audio and video portions to be out of sync, because of dropped frames during swapping.
QuickTime software that does more actual processing (like Adobe Premiere, for example) can benefit from being native - that extra horsepower will really help when applying a filter or process on every frame of a movie.
People have been doing CD-quality sound input and output on Mac IIci's (with special NuBus cards) for years: 2 channels x 16 bits/channel x 44100 Hz = 1.35 MBits/sec or so. QuickCam is not so different: 4 bits/pixel x 160x120 pixels/frame x 15 frames/sec = 1.1 MBits/sec (average).
David Ramsey wrote a column about how to open up a QuickCam. Should I?
We do not support disassembling the QuickCam for any reason because:
1. It invalidates the warranty immediately. Please read page 38 of your
QuickCam manual - opening your QuickCam falls under the category of
"Unauthorized modification."
2. The camera mechanism is very sensitive, and any non-Connectix adjustments
will most likely lead to a damaged camera.
3. Many of the components on the QuickCam electronics board are surface
mount components that are close to the edge of the board and easily
damaged if the case is not removed or put together properly. And the case
was not designed to be field opened. So, unless you
have the jig to properly align the board and shell halves, it is very
likely that you will break one of these components.
We understand your desire to test the limits of this great little tool, but the risks involved in opening the camera far outweigh the possible gains (a closer minimum focused distance). We are exploring different optical configurations and accessories for the camera, but for now, we recommend working with the camera as it is.
