I am building an app for iOS (iPhone and iPad) where the user is able to watch video clips of therapeutic exercises. However, I want to overlay some dynamically generated information (the amount of reps and sets assigned to them by their physio) either "over" or next to the video playing. The amount of reps and sets will be like a counter counting down the amount of work they have left before the next exercise will start playing.
Here is a mock-up of what I would like to achieve if possible Video with dynamic information overlay
So while the video is playing the "Hold" will count for a specified number of seconds. When the time limit is reached, "Sets" is increased by 1 and Hold starts from 0 again. When the Sets are all completed, "Reps" increase by 1 and Hold and Reps start back at 0. Etc.
Can the video playing and all this information be displayed simultaneously on the iPhone/iPad?
I have looked at a number of video hosting solutions that might have this feature built into it, but couldnt find anything that would suit my needs.
Is this possible at all as I have never seen anything like this done before?
Could a solution be to use a iFrame to display the video and then have all the other information that I want on the screen separate to this? Just a thought...
Yes, this is possible, have a look at this example project:
http://www.musicalgeometry.com/?p=1273
This is for a camera overlay, but it also works for existing videos.
Related
Desired output (pun intended)
Capture video (and audio) and then directly apply time stamp and GPS coordinates as a layer on top of the video to instantly/directly embed them in the recording. (e.g. via subview/layer or CIFilter). The text layer is dynamic, e.g. timestamp keeps changing as film is rolling.
How To Add Text to Video in Swift and AVFoundation Tutorial: Adding Overlays and Animations to Videos both describes how to do it in post production (i.e. when the file is already saved). But this adds considerable time to UX, e.g if you record a 1 min video, this would take another 30 seconds to embed after, not desired UX.
Is there a way to embed the text/CIfilter directly before saving the video?
The approach of editing each frame "manually" in capture output is slow (5-10 frames per second only).
Adding AVVideoCompositing seem like the right approach, but I don't know where to "hook it up". In the AVCaptureOutput? Or is it possible directly in the AVCaptureMovieFileOutput?
Does anyone have a GitHub repo or sample code of how to approach?
Any help appreciated. Thank you!
I have some related question re: video processing on iOS.
1) Is it possible to pause, then resume, an AVVideoComposition processing session? I ask this because I've run into problems merging large 1080p video files together when my app is running in the background (i.e., the 10-minute background processing limit for apps). My experience so far has been that the video processing session fails if the app is in the background when the 10-minute limit is hit and the app gets stalled by iOS. If I were able to pause the video processing session, I could detect the approach of the 10-minute limit, then pause the video processing until the user brings the app back to the forefront, then resume it, etc., etc.
2) In lieu of the above capability, is there a way to "extend" background processing for longer than 10 minutes? My app does not fit under any of the categories of apps that are permitted to run continuously in the background. But my need to do so for my app is legitimate and genuine - the reason being that videos on the iphone are huge - 1080p with the newer iphones - and processing them takes a while. In a way, it's not fair to users to limit an app's ability to process video taken on their behalf on the device the video was captured with. Bottom line: an app should be allowed to either continue it to it's completions, or pause and resume at a later time, as long as it's in the middle of an AVComposition video processing session.
3) If neither of the above options is available, could you please recommend a strategy for dealing with this issue. I want to make my app rock-solid in terms of reliability and letting the user know exactly what is going on.
4) Is it possible to up-convert a lower quality video to a higher (albeit fuzzier) quality? For example: say I want to merge two video clips, one a lower quality and one a higher quality. Currently, if I merge these two together, the resulting video plays at the resolution of the higher-quality video; the portion containing the lower-quality video plays in a smaller video frame in the upper-left corner of the larger video frame, with the rest of the frame blacked out. What I'd prefer is to have the lower-quality video fill the larger frame, even if it gets fuzzy as a result. (NOTE: I do want to maintain the aspect ratio of the lower quality video, however, so black bands across top/bottom or left/right are OK.)
Thanks!
I'm a new developer and I want to know if it is possible to record a video and process it so that specific text is displayed above/below or inside the video.
Specifically, my educational app displays random words in a text label at a regular interval, and I want my user to be able to record himself saying those words with the front facing camera. Then I'd like to save that video with the words added to it-- that means that during video playback the user would see all of the words come up as he saw them during recording.
I'm wondering if this text display (and synchronization) are possible.
Does anyone have any suggestions or pointers in the right direction (if this is even possible)?
Apple has a ton of documentation on Core Media Time.
Create a list of times at which you want each word to appear and disappear, then compare those times against the running time of the recording in a timer or frame rate callback, to decide what word to (re)draw onto a view or layer.
As long as the videos are in full (there are no stops at all) and they are recorded at the same frame rate then you just need to find one point that you can find the sync point and the rest will be in sync. Another option is to record the timestamp of when the text you want to appear. That way you can subtract between two texts to get the duration of the text.
There are a few SO questions regarding frame by frame animation (such as frame by frame animation and other similar questions), however I feel mine is different so here goes.
This is partially a design question from someone with very little ios experience.
I'm not sure "frame by frame" is the correct description of what I want to do so let me describe that. Basically, I have a "script" of an animated movie and I'd like to play this script.
This script is a json file which describes a set of scenes. In each scene there are a few elements such as a background image, a list of actors with their positions and a background sound clip. Further, for each actor and background there's an image file that represents it. (it's a bit more complex - each actor has a "behavior" such as how it blinks, how he talks etc). So my job is to follow the given script referencing actors and background and with every frame, place the actors in their designated position, draw the correct background and play the sound file.
The movie may be paused, scrubbed forward or backward similar to youtube's movie player functionality.
Most of the questions I've seen which refer to frame-by-frame animation have different requirements than I do (I'll list some more requirements later). They usually suggest to use animationImages property of a UIImageView. This is fine for animating a button or a checkbox but they all assume there's a short and predefined set of images that need to be played.
If I were to go with animationImages I'd have to pre-create all the images up front and my pure guess is that it won't scale (think about 30fps for one minute, you get 60*30=1800 images. Plus the scrub and pause/play abilities seem challenging in this case).
So I'm looking for the right way to do this. My instinct, and I'm learning more as I go, is that there are probably three or four main ways to achieve this.
By using Core Animations and defining "keypoints" and animated transitions b/w those keypoints. For example if an actor needs to be at point A at time t1 and point B at time t2 then all I need to do it animate what's in between. I've done something similar in ActionScript in the past and it was nice but was particularly challenging to implement the scrub action and keep everytyhing in sync so I'm not a big fan of the approach. Imagine that you have to implement a pause in the middle of an animation or scrub to a middle of an animation. It's doable but not pleasant.
Set a timer for, say 30 times a second and on every tick consult the model (the model is the script json file along with the description of the actors and the backgrounds) and draw what needs to be drawn at this time. Use Quartz 2D's API and drawRect. This is probably the simple approach and but I don't have enough experience to tell how well it's going to work on different devices, probably CPU wise, it all depends on the amount of calculations I need to make on each tick and the amount of effort it takes ios to draw everything. I don't have a hunch.
Similar to 2, but use OpenGL to draw. I prefer 2 b/c the API is easier but perhaps resource wise OpenGL is more suitable.
Use a game framework such as cocos2d which I'd never used before but seems to be solving more or less similar problems. They seem to have a nice API so I'd be happy if I could find all my requirements answered by them.
Atop of the requirements I'd just described (play a movie given it's "script" file and a description of the actors, backgrounds and sounds), there's another set of requirements -
The movie needs to be played in full screen mode or partial screen mode (where the rest of the screen is dedicated to other controls)
I'm starting with the iphone by naturally an ipad should follow.
I'd like to be able to create a thumbnail of this movie for local phone use (display it in a gallery in my application). The thumbnail may just be the first frame of the movie.
I want to be able to "export" the result as a movie, something that could be easily uploaded to youtube or facebook.
So the big question here is whether any of the suggested 1-4 implementations I have in mind (or others you might suggest) can somehow export such a movie.
If all four fail on the movie export task then I have an alternative in mind. The alternative is to use a server which runs ffmpeg and which accept a bundle of all the movie images (I'd have to draw them in the phone and upload them to the sever by their sequence) and then the server would compile all the images with their soundtrack to a single movie.
Obviously to keep things simple I'd prefer to do this server-less, i.e. be able to export the movie from the iphone but if that's too much to ask then the last requirement would be to at least be able to export the set of all images (keyframes in the movie) so I can bundle them and upload to a server.
The length of the movie is supposed to be a one or two minutes. I hope the question wasn't too long and that it's clear...
Thanks!
well written question. for your video export needs check out AVFoundation (available as of iOS 4). If I were going to implement this, I'd try #1 or #4. I think #1 might be the quickest to just try out, but that's probably because I don't have any experience with cocos2d. I think you will be able to pause and scrub CoreAnimation: check out the CAMediaTiming protocol it adopts.
Ran, you do have a number of options. You are not going to find a "complete solution" but it will be possible to make use of existing libraries in order to skip a bunch of implementation and performance issues. You can of course try to build this whole thing in OpenGL, but my advice is that you go with another approach. What I suggest is that you render the entire "video" frame by frame on the device based on your json settings. That basically comes down to setting up your scene elements and then determining the positions of each element for times [0, 1, 2] where each number indicates a frame at some framerate (15, 20, or 24 FPS would be more than enough). First off, please have a look at my library for non-trivial iOS animations, in it you will find a class named AVOfflineComposition that does the "comp items and save to a file on disk" step. Obviously, this class does not do everything you need, but it is a good starting point for the basic logic of creating a comp of N elements and writing the results out to a video file. The point of creating a comp is that all of your code that reads settings and places objects at a specific spot in the comp can be run in an offline mode and the result you get at the end is a video file. Compare this to all the details involved with maintaining all theses elements in memory and then going forward more quickly or slowly depending on how quickly everything is running.
The next step will be to create 1 audio file that is the length that the "movie" of all the comped frames and have it include any sounds at specific times. This basically means mixing the audio at runtime and saving the results to an output file so that the results are easy to play with AVAudioPlayer. You can have a look at some very simple PCM mixer code that I wrote for this type of thing. But, you might want to consider a more complete audio engine like theamazingaudioengine.
Once you have an audio file and a movie file, these can be played together and kept in sync quite easily using the AVAnimatorMedia class. Take a look at this AVSync example for source code that shows a tightly synced example of playing a video and showing a movie.
Your last requirement can be implemented with the AVAssetWriterConvertFromMaxvid class, it implements logic that will read a .mvid movie file and write it as a h.264 encoded video using the h.264 encoder hardware on the iPhone or iPad. With this code, you will not need to write a ffmpeg based server module. Also, that would not work anyway because it would take too long to upload all the uncompressed video to your server. You need to compress the video to h.264 before it can be uploaded or emailed from the app.
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.