Mac Daddy World

The iApps like iChat and Photo Booth only request a 640×480 or smaller image from the iSight. Therefore it can be troublesome to find a way to test the full capabilities of the new 1.3 MP iSight. That’s why we wrote our own little test program.

Today we cleaned it up and are posting it here so new-MacBook-Pro-having visitors can try it out see the new and improved image for themselves.

The app requests and displays a video stream from the camera at 1280×1024. If you’re on an older iSight it will still stretch the VGA image out to be this size but it won’t look very good. The app will report the frame actual size from the ImageDescription at the top.

There’s also a snapshot button so you can take your own picture and make your friends jealous of your fancy new laptop. Sorry: no Photo Booth effects yet!

If you get to try it, leave a comment and let me know how it works for you.
The Test App (68 k)

Tech Talk Follows:

The app does Hi-Lite™ a potential reason why Apple might not be yelling from the rooftops about the new camera: You can see right away how slow it is to stream the full sized video. Why? It’s more than four times more data than VGA. The Sequence Grabber was designed decades ago and wasn’t designed to handle more than NTSC/PAL sizes. Until the Sequence Grabber is revamped, it’s a little too slow to run such a large stream.

1,280 x 1,024 = 1,310,720 pixels
It’s 4:2:2 compressed YUV data, so that’s 2 bytes per pixel or 2,621,440, or 2.5 megabytes per raw frame.
So for full 30 fps video, this translates to about 75 megabytes per second or 600 Mbps.
Now keep in mind the camera controller allows for a compressed MJPEG mode which cuts the required USB bandwidth signifcantly. (You’d never fit that over USB 2.0 without compression.)

But even if it is being compressed on-camera, it’s then being decompressed in the driver and passed to QuickTime in YUV. That’s a lot of data to push through the poor Sequence Grabber pipes. Technically, you should be able to request MJPEG data from the sequence grabber, but the default seems to be YUV. I haven’t tried requesting other compression types as I don’t actually have one of these new machines in front of me.*

More details about the new camera:

The original iSight didn’t advertise itself as a UVC device (It was Vendor Specific).
The new one does advertise as UVC, so you can easily use USB Prober to decode the device descriptor:
According to the descriptor the camera supports the following frame formats:

MJPEG 640×480 @ up to 60fps
MJPEG 720×480 @ up to 60fps
MJPEG 800×600 @ up to 30fps
MJPEG 1024×576 @ up to 30fps
MJPEG 1024×768 @ up to 30fps
MJPEG 1280×960 @ up to 30fps
MJPEG 1280×1024 @ up to 30fps
Uncompressed 640×480 @ up to 30 fps
Uncompressed 352×288 @ up to 30 fps
Uncompressed 160×120 @ up to 30 fps
Uncompressed 704×576 @ up to 25 fps
Uncompressed 720×480 @ up to 25 fps

Maybe another SequenceGrabber savvy engineer out there with the new MBP could experiment and see what you get back from VDGetCompressionTypes. Can we request MJPEG data through the pipes?

*Another thanks to Dave for running some tests for me on his MBP. Dave is a web designer and has a website that I’ll plug.

or… Built-in iSight The Next Generation 

At WWDC, Glen had the unenviable task of hitting the compatibility lab and testing the upcoming release of iGlasses on as many computers as he could.  When checking out the new 2.2 and 2.4 GHz MacBook Pros, he noticed something interesting about the built-in iSight:

It’s a whole new camera.  Really!

First, looking at System Profiler:

It has a new USB PID.  What I’ll henceforth have to refer to as the original built-in iSight, had the USB Product ID: 0×8501 and reports its manufacturer as Micron. The new built-in iSight has the Product ID of 0×8502 and reports manufacturer of Apple Inc.   

Now the cool part:  It’s a 1.3 megapixel sensor!  I wrote a simple test application to capture a frame of video using an SGDataProc and save it to the Desktop.  On my older 2.33 GHz MB Pro with the original built-in iSight, what I get is a VGA (640×480) image.  This is the maximum size of the original camera, which I know for sure uses a VGA sensor.

Then, braving the 95 degree the heat, we got on our bikes and cruised down to the Cambridge Apple Store.  After fighting our way through the crowds of people asking if they can pre-order an iPhone, we commandeered some MB Pros.  The same test program produced a nice, big 1.3 MP (1280×1024) image. 

UPDATE: Test app available here.

Other differences:

The new camera supports all of the VDSetBrightness, VDSetContrast, etc. calls. The old camera only supported Saturation and Sharpness.  This causes an odd bug in iGlasses which we’ll have to fix very soon.

Whereas the original camera was uyvy (’2vuy’ in QuickTime), the new camera’s data is yuyv compressed. (that’s YUY2 for you Windows users or ‘yuvs’ in QuickTime parlance.) It’s the same as the previous 4:2:2 format except the 16-bit words are byte swapped. This doesn’t cause a problem for iGlasses which knows how to deal with both data types as this is the YUV format used by our iMage USB Webcam.

Interesting:

- I haven’t verified this yet, but I’m going to guess that 10.4.10 (which includes a new 2.0 version of the UVC driver) is required to get the larger sized image.  This would explain why nobody noticed this last month when they were first released.

- I’m guessing they’re still using a Micron sensor.  A few sources have indicated that the iPhone will also use a Micron sensor for its camera.  The phone is supposed to have a 2 MP camera. 

- iChat and other iApps don’t take advantage of the larger image size.  If we stretched our iChat preview window up to around 1280 wide (the aspect ratio is not 4:3 in iChat 3), it was clear that we were looking at a VGA image scaled up.  iChat and other such apps are probably calling SGSetChannelBounds with 320×240 or 640×480 because that’s the size they use for conferences, whereas I’m specifying a really large size (1600×1200).

- Thanks to Dave for letting me mess around with his new laptop this afternoon.