I'm building an iOS app which requires me to allow the users to record a 15sec clip (with UIImagePickerController for example) and then convert it into an animated GIF. How could I achieve this? Is there any library/framework available for such task?
Thanks!
This gist code piece may help you.
https://gist.github.com/mayoff/4969104
It shows how to export frames into a gif image.
I don't believe there is any existing library that would do a straight conversion for you. There's a lot of libraries for displaying animated GIFs - far fewer native Objective-C libraries for creating them.
Fortunately, iOS does have support for saving as GIFs. There's an existing StackOverflow answer that covers how to create animated GIFs in-depth here:
Create and and export an animated gif via iOS?
...there's also a library on GitHub that abstracts the lower-level stuff away, although it's not been maintained for a while (link here).
All you'll need to do is create an array of the frames you want to convert into your GIF. I strongly recommend you don't try and convert every single frame in your 15 second video, if only because you'll end up with a very large GIF at a frame-rate that's too high. You would be better off picking every other, or even every 3/4 frames from your video sample. Capturing images from video is also pretty well documented on iOS.
I recently created a library called Regift for converting videos to gifs on iOS. Hopefully it will help anyone coming to this in the future :)
Related
I wrote a basic animation framework using Core Animation on iPhone. It has the functionality for pause and resume of animations and also can run animations at specified time. My basic problem is that I cannot find a way to export my animations to a video file (.mov, .avi etc). I have read about AVAssetWriter and AVComposition but cannot understand how to make them work in my case.
By searching the internet the closest I was able to get was it by doing frame by frame reading of my animations. Even for it I could not find a way to make it work and could not find that whether iPhone SDK have something to do that for this kind of frame by frame reading in my case. I also came close to this question on stackoverflow and still could not figure out (sorry if I feel that I am beginner in those things, but I am not, just could not understand some things)
If anyone know how to make it work or even how to something similar to it please share. And if there is no way then if you know any other way to do i.e using OpenGL ES instead of CoreAnimation please share it too.
Check this presentation: http://www.slideshare.net/invalidname/advanced-media-manipulation-with-av-foundation
Around page 84 he talks about adding animation to video compositions. I believe this will help you get what you need.
EDIT: Specifically you need to look at the animationTool of your video composition. This is a AVVideoCompositionCoreAnimationTool object that allows you to add a core animation layer to your output video. See also this question:
Recording custom overlay on iPhone
I am sorry I do not have the time to get you a full code snippet, but basically you set this animation tool of your video composition, and then create an AVAssetExportSession and set its videoComposition to the one you made.
I am looking to replicate the image gallery view that shows thumbnails, like in the photos app on the iPhone.
Is there a view controller or any examples that anyone can provide to replicate this?
There isn't one provided by Apple. I would recommend looking at Three20. It has a few things with look a lot like the Photos app.
Another option is AQGridView.
Take a look at the video of Session 104 from the WWDC 2010. It's basically a 40 minute tutorial on how to do the photo app.
Bear in mind that allowing users to zoom will greatly increase the space required. If you use CATiledLayers, that is, which, depending on your desired zoom level, you should consider doing.
Oh, and there is source code ;)
What they don't tell you is how they did their tiling. I found that you can
a) download ready-made tiles from the server with the app or with a content update (you can use ImageMagick's crop tileWidthXtileHeight - e.g. crop 100x100 - to do the tiling). This has the disadvantage of large downloads.
b) download ready-made tiles from the server as needed (may lead to lags in your app, but then MKMapView does it quite nicely, doesn't it?)
c) tile on the phone as needed (here you can also consider caching the results, although that will likely mean you have to check space left on the device)
I've recently given enormego's PhotoViewer a try. It's easy to use, and it's much more focused than the Three20 project. (Which I also use and like a lot.)
I have to figure out the best way to transition from one video to the next
BASIC IDEA: An example would be that there is a video of a person walking.....the user taps the video and a seamless transition occurs to a video of a person running (over simplified example)
My first thought was to create 2 movie players and use transitions between the 2 view elements. But movie-player doesn't support that.
stopping the current video, loading new content, and then starting it is a solution but not very elegant. We are making a interactive sales tool for our reps and we want this to look as professional as possible.
CURRENT THOUGHT: If there was some sample code for AVPlayer, it would seem I could use AVVideoComposition to switch between videos? But details on how that might happen don't seem to be currently available.
POSSIBLE CLUE: I figured this would be easy as I bought an app called Live Cams HD that shows 16 different video feeds at once.
Any ideas? Thanks in advance!
Steve, the short answer is that you are not going to be able to get the kind of results you want using AVPlayer. The h.264 video logic included in iOS is really great at playing video and video/audio together, but it really sucks at starting/stopping and switching from one clip to another. The reason is that there is a lot of buffering that needs to happen to load up and start playing a h.264 video in hardware. Basically, you need to roll your own code that sets UIImage/CGImageRef for your views in a way that makes it easy to switch from one clip to another by simply switching from one array of UIImage objects to another. Of course, that is easy to say yet not so easy to implement.
What I would suggest is that you evaluate existing code that already implements this logic instead of rolling your own. For example, have a look at this StreetFighter demo app. It shows how a very simple game like iPhone UI can be constructed using a series of clips that show a character doing a kick, a punch, or throwing a fireball. The results looks like this:
I also wrote up a blog post about seamless-video-looping-on-ios. You can of course roll your own code to do all this, but I would suggest reading more about my library at the linked website as it will save you a lot of time.
After the first video has played every frame except the last one, you quickly swap to a view with an image of the last frame (basically the last frame) and then you transition into a view with the an image of the first frame of the next video and start up that one.
Or you could create a animation with all your frames (programming your videos), that will make it customizable, but the quality will probably not be as good and the cpu usage can spike, so you will have to make a call on that one.
Does anyone know how to do this?
Is anyone able to provide an example? I believe this is out of NDA now as was available in version 4.0 ?
Take a look to AVFoundation framework , specially to avcapture avsession avinputdevice, etc. You can find some listings in the iPhone dev center forums: search "avcapture"
AVFoundation is the framework you want to use to record, modify raw frames, show them, an offcourse add some overlay
If you want to do only overlay then, UIImagePickerController should b enough.
If i understand, what you are trying to do corectly, you have set up video capture someting like suggested by Apple in this Q&A:http://developer.apple.com/iphone/library/qa/qa2010/qa1702.html
From there it shouldn't be much of a Problem to use the method described in this answer:blend two uiimages based on alpha/transparency of top image to blend the preview with your overlay, provided you draw it in a UIImage first. Feed the resulting images to a buffer and save it accordingly.
Though, this method most certainly wouldn't give you a lot of frames per second.
From what I have gathered from internets the MPMoviePlayerController class doesn't support small video playback. So, in an effort to beat a dead horse I was wondering what kind of methods could be used to get a small video playing in a corner of the screen without interrupting the rest of the screen.
So far we've come across two solutions that may work: using a UIImageView and flopping images through it like a madman and using a large fullscreen video with all the animations we need already on it and skipping around as needed.
Am I wrong about the MPMoviePlayerController not supporting non-fullscreen video? Is their an easier solution than making UIImageView flip-books? Is cutting around a video a performance hazard?
I think you're stuck with flip books. Pretty sure the fullscreen video issue is a limitation of the hardware video decoder.
After researching for about 1 hour, I didn't find anything. It appears impossible to play video non-fullscreen on the iPhone. I didn't check for openGL ES though.
well.. i have been looking for and haven't found the alternate yet!
But there are some applications already does it!
check TVUlite from TVUNetworks
As I mentioned in another reply, this blog post http://www.nightirion.com/2010/01/scaling-a-movie-on-the-iphone/ mentions a method that will allow you to play non-fullscreen video. However, I'm not sure if this method will be approved by the app store verification process.