这里是捕获视频并保存视频的代码。然而，它并没有保存视频内容，而是返回了错误信息：JavaScript运行时错误：类型不匹配。问题出现在saveVideo函数的copyAsync方法中。
function captureVideo() {
var cam = Windows.Media.Capture.CameraCaptureUI();
cam.videoSettings.allowTrimming = true;
cam.videoSettings.format = Windows.Media.Capture.CameraCaptureUIVideoFormat.mp4;
cam.videoSettings.maxResolution = Windows.Media.Capture.CameraCaptureUIMaxVideoResolution.standardDefinition;
cam.captureFileAsync(Windows.Media.Capture.CameraCaptureUIMode.video).then(function (file) {
if (file) {
photoBlobUrl = URL.createObjectURL(file, { oneTimeOnly: true });
var myVideo = document.getElementById("videoId");
myVideo.src = photoBlobUrl;
myVideo.play();
}
else {
}
});
}
function saveVideo() {
var output;
var input;
var outputStream;
var picturesLib = Windows.Storage.KnownFolders.picturesLibrary;
picturesLib.createFileAsync("v1.mp4",
Windows.Storage.CreationCollisionOption.replaceExisting).
then(function(file) {
return file.openAsync(Windows.Storage.FileAccessMode.readWrite);
}).then(function (stream) {
outputStream = stream;
output = stream.getOutputStreamAt(0);
input = photoBlobUrl;
return Windows.Storage.Streams.RandomAccessStream.copyAsync(input, output);
}).then(function() {
return output.flushAsync();
}).done(function() {
input.close();
output.close();
outputStream.close();
});
}