UPDATE (06/03/2012): I've posted a full article on optimizing Display Recorder on the iPad 3 HERE. The article can also be useful for owners of other models as it explains, among other things, how your videos can easily be rotated, how to achieve the best possible performance etc.
Original article follows:
I've long (since last June) been planning to publish a huge article on Ryan Petrich's excellent “Display Recorder” application, which makes it possible to record your screen content right on your iDevice.
Up until now, I've waited because the developer has been promising great upgrades like seamless video recording and, what is more, audio recording. Just a while ago, all these new functionality has been added to the just-released 1.3.0 version.
First of all, there are cases when you will NOT want to use screen recorders running on an iDevice. An example of this is showing what, say, a high-FPS (frame per second) game is capable of. If you're a dev, then, just run it in the emulator and record it with a decent OS X screen recorder – there are quite a few of them. On the other hand, if you don't have access to the sources of the title, you will want to use an external camera in a lot of other cases when the rendering speed is of extreme importance. (Just make sure you use a camera capable of at least 30 fps video recording; preferable 60 fps non-interlaced. Let me know if you need more information on taking videos with cameras – if you're active on DPReview, you may have noticed I'm pretty much interested in cameras and shooting and post a lot of comments / forum posts.)
However, in cases like recording Skype video calls, particularly when you don't have an external camera for doing the recording (because you're, say, outdoors e.g. travelling), an app running right on your iPhone is essential. (Note that FaceTime calls are a different matter – more on them later.)
So far, there was no way you could record Skype calls properly; that is, with audio. Actually, there was no way you could record audio during Skype calls at all – the system stopped any kind of (standard) audio recording activities as soon as you started (or received) a Skype call, just as with normal phone calls.
What will you need to do?
First, jailbreak your iDevice. Currently, ALL iDevice models, assuming they're on the most current iOS version (2007 models (iPhone 1, iPod touch (iPt) 1): 3.1.3; 2008 models (iPt2, iPhone 3G): 4.2.1; 2009+ models (iPt3+, iPhone 3GS+, iPad1+)) can be jailbroken. For A5-based models running 5.0.1 (iPad 2, iPhone 4S), you'll need Absinthe; for other models running on any iOS version (including 5.0.1), Redsn0w. There are tons of decent tutorials (even video ones) on jailbreaking; please do a Google search if you're unsure about them. Generally, as the 5.0.1 jailbreak is untethered (as is 3.1.3 / 4.2.1 for first- and second-generation devices), you can safely jailbreak. Just keep in mind you'll want to fully restore the factory settings (under Settings > General > Reset > Erase All Content and Settings) if you, for some reason, need to have it serviced - it'll completely remove all tracks of the previous jailbreak.
Then, in Cydia, search for and download “Display Recorder”. After this, go to Settings > Display Recorder > Video Format and select H.264/MOV with Mic. Audio. Generally, this will be sufficient. (You might also want to reconfigure the app to use some other activation method instead of the 1sec Power button-press. I haven't done so; this is why I use the Power button in the demo video below for activation.)
After this, by short (about for a second)-pressing the Power button, a “Start recording display?” dialog will appear. Upon answering “Yes”, recording will start. You can stop it by either short-pressing the Power button again (which stops the recording) and just selecting either OK to keep the recording or Delete if you want to delete it. You can also check out the recordings you've made by tapping the “Display Recorder” icon on SpringBoard. Upon tapping anything in the video list, a context menu will be presented. There, you can play back (“Play Video”) the video and also add to the camera roll so that you can easily access it with desktop camera tools (and from the built-in Photos app). All these (excluding adding to the camera roll) is shown in the demo video below.
On the iPad, upon playback, you'll want to rotate the iPad and lock the rotation to get the video correctly rotated. (Of course, the controls will still remain in Portrait orientation.) On the iPhone, playback will have the right orientation. This is also shown in the video below.
Skype call recording
While you can record most apps not using either OpenGL ES or hardware-accelerated video playback / capture (Skype, while it does use the camera, doesn't use acceleration so it doesn't belong to this category), one of the most useful ways you can make use of it (assuming you're a Skype user) is recording Skype calls.
You'll need to do this the following: start the recording (short-press Power and select “OK”) after you've established the connection – NOT before! This is very important. This also means you won't want to quickly leave Skype and, then, return to it while calling (and recording). Otherwise, recording will stop with a “Recording errored” (sic!) error message and the file saved to the Display Recorder will be invalid, meaning not a single second of it will be usable.
In the video demo below, I present Skype recording on both the iPad 2 and the iPod touch 4. I record (and, then, play back) video on both iDevices, also demonstrating audio recording (and playback) on both. Also note that, as emphasized above, I only start recording after the connection is established.
1. the developer will not add automatic video recording of, say, Skype calls because of legal reasons. Interestingly, on the desktop, there are Skype call recorders (for example, Ecamm's one at http://www.ecamm.com/mac/callrecorder/ ) that do record automatically.
2. the new Display Recorder may be able to record ordinary phone (non-Skype) calls as well. I'll report on this as soon as possible. (Have left my iPhones at work so I can't test it right now. Will do it ASAP.)
3. on slower hardware (anything pre-A5; that is, everything except the latest iPad 2 / iPhone 4S) recording Skype video calls will drastically slow down the camera speed to about 1 FPS or even less (this is also visible on the demo above – as soon as I enabled video recording on the iPod touch 4, the video delivered to the other participant greatly slowed down). The audio may also be transferred incorrectly and with problems. If the other side encounters major problems because of this, you'll want to stop recording (or upgrade to more up-to-date hardware). On the latest-generation (A5) devices, the performance hit is much smaller and there aren't problems at all.
4. FaceTime recording isn't supported. If you do start recording FaceTime calls, you won't be able to stop recording.
UPDATE (02/13): I've tested phone call recording on the iPhone 4S. Unfortunately, it doesn't work. If you start recording before starting / answering the call, silence will be recorded; if you start it when already in conversation (as needs to be done with Skype calls), you won't be able to stop recording at all (without resetting the phone) – as is the case with FaceTime calls. I REALLY hope the dev looks into enabling call recording.
Skype video recording worked just fine on the 4S. Unlike previous-generation devices (for example, the A4-based iPt4 also shown in the demo video), the performance hit wasn't too big on the 4S.