hnical functionality that can’t be replicated on the native iOS SDK can work through a third party’s system. So just to share with you some of the results, I was attempting to play four transparent videos, all slightly overlapping with a png image in the background. The playback was unacceptably slow with this many streams. I then tried, two transparent videos with a PNG background and the playback was fine, I didn’t notice any frame grabbing or glitches, and one full screen iPhone video with transparency and a PNG image in the back ground ran fine!

Again, I’d like to express my amazement at being able to play an .flv with transparency on the iPhone. I have no idea how Adobe are able to do it, but I really hope Apple step up their game and include a video codec with alpha channel sometime soon. The only down side to using ARI 2.7 is the lack of support for native UIKit components, meaning you have to build everything in Flash/Flex.

If you want to play around with transparent video on the iPhone with Flash you’ll need to download the trial version of Flash Builder 4.5 from here, and check out this post on setting up your system to export from Flash Builder to your iPhone. You do need to be registered as an Apple dev, as to my knowledge there is no simulator in the Adobe set up, but it was all pretty straight forward (no less painful than having to do it through Apple and XCode).

Here’s the AS3 code, I just created a new Mobile ActionScript Project, as I’ve heard Flex Mobile Projects add unwanted overhead to your app (but don’t quote me on that). You’ll also need to make sure that the info in the project’s XML file (application descriptor file) matches all of your code signing identity info ie com.mycompany.myAppID
One thing to note is that I didn’t use the StageWebView object to place my video. According to Adobe’s docs StageWebView’s shouldn’t overlap with each other, so this wasn’t suitable for this project. The only piece of AIR specific code is the

Not a full fledge player like whats a

H.264 only

Christopher Blizzard, Mozilla's open source evangelist, also defends the decision saying that h264 has unpredictable licensing costs and refers back to the GIF and MP3 situations where a widely used, apparently royalty free format turned out to have patents and licence costs which emerged later, after the formats were ubiquitous on the web.

One important thing about playing an H.264 video file as progressive download is that the moov atom needs to be located at the beginning of the file, or else the entire file will have to be downloaded before it begins playing. The moov atom is a part of the file that holds index information for the whole file. Unfortunately, tools such as Adobe Premiere and After Effects place this information at the end of the file, but Adobe is working to fix this in a future update to the CS3 video production tools. This isn't an issue for streaming the H.264 video files, however, so Flash Media Server users can breathe easy.