MICROSOFT_PRESS_EBOOK_PROGRAMMING_WINDOWS_8_APPS_WITH_HTML_CSS_AND_JAVASCRIPT_PDF

FIGURE 10-9 Previewing and recording video with the default device in the Media capture sample, Scenario 1. (The
output is cropped because I needed to run the app using the Local Machine option in Visual Studio, and I didn’t
think you needed to see a 1920x1200 screenshot with lots of whitespace!).
Notice the Contrast and Brightness controls in Figure 10-9. Changing these will change the preview
video, along with the recorded video. The sample does this through the MediaCapture.video-
DeviceController object’s contrast and brightness properties, showing that these (and any others in
the controller) can be adjusted dynamically. Refer to the getCameraSettings function in
js/BasicCapture.js that basically wires the slider change events into a generic anonymous function to
update the desired property.
Selecting a Media Capture Device
Looking now at Scenario 2 (js/AdvancedCapture.js), it’s more or less like Scenario 1 but it allows you to
select the specific input device. Until now, everything we’ve done has simply used the default device,
but you’re not limited to that, of course. You can use the Windows.Devices.Enumeration API to retrieve
a list of devices within a particular device interface class; the sample uses the predefined videoCapture
class:
function enumerateCameras() {
var cameraSelect = id("cameraSelect");
deviceList = null;
deviceList = new Array();
while (cameraSelect.length > 0) {
cameraSelect.remove(0);
}
//Enumerate webcams and add them to the list
var deviceInfo = Windows.Devices.Enumeration.DeviceInformation;
deviceInfo.findAllAsync(Windows.Devices.Enumeration.DeviceClass.videoCapture)
.done(function (devices) {
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