Stream video while downloading iOS

Question

I am using iOS 7 and I have a .mp4 video that I need to download in my app. The video is large (~ 1 GB) which is why it is not included as part of the app. I want the user to be

Answer 1

I figured out how to do this, and it is much simpler than my original idea.

First, since my video is in .mp4, the MPMoviePlayerViewController or AVPlayer class can play it directly from a web server - I don't need to implement anything special and they can still seek to any point in the video. This must be part of how the .mp4 encoding works with the movie players. So, I just have the raw file available on the server - no special headers required.

Next, when the user decides to play the video I immediately start playing the video from the server URL:

NSURL *url=[NSURL fileURLWithPath:serverVidelFileURLString];
controller = [[MPMoviePlayerViewController alloc] initWithContentURL:url];
controller.moviePlayer.scalingMode = MPMovieScalingModeAspectFit;
[self presentMoviePlayerViewControllerAnimated:controller];

This makes it so the user can watch the video and seek to any location they want. Then, I start downloading the file manually using NSURLConnection like I had been doing above, except now I am not streaming the file, I just download it directly. This way I don't need the custom header since the file size is included in the HTTP response.

When my background download completes, I switch the playing item from the server URL to the local file. This is important for network performance because the movie players only download a few seconds ahead of what the user is watching. Being able to switch to the local file as soon as possible is key to avoid downloading too much duplicate data:

NSTimeInterval currentPlaybackTime = videoController.moviePlayer.currentPlaybackTime;

[controller.moviePlayer setContentURL:url];
[controller.moviePlayer setCurrentPlaybackTime:currentPlaybackTime];
[controller.moviePlayer play];

This method does have the user downloading two video files at the same time initially, but initial testing on the network speeds my users will be using shows it only increases the download time by a few seconds. Works for me!

Answer 2

I can only assume that the MPMoviePlayerViewController caches the file length of the file when you started it.

The way to fix (just) this issue is to first determine how large the file is. Then create a file of that length. Keeping an offset pointer, as the file downloads, you can overwrite the "null" values in the file with the real data.

So you get to a specific point in the download, start the MPMoviePlayerViewController, and let it run. I'd also suggest you use the "F_NOCACHE" flag (with fcntl()) so you bypass the file block cache (which means you will lower your memory footprint).

The downside to this architecture is that if you get stalled, and the movie player gets ahead of you, well, the user is going to have a pretty bad experience. Not sure if there is any way for you to monitor and take preemptive action.

EDIT: its quite possible that the video is not read sequentially, but certain information requires the player to essentially look ahead for something. If so, then this is doomed to fail. The only other possible solution is to use some software tool to sequentially order the file (I'm no video expert so cannot comment from experience on any of the above).

To test this out, you can construct a "damaged" video of varying lengths, and test that to see what works and what does not. For instance, suppose you have a 100Meg file. Write a little utility program, and over write the last 50Megs of data with zeros. Now play this video. Its should fail 1/2 through. If it fails right away, well, you now know that its seeking in the file.

If non sequential, its possible that its looking at the last 1000 bytes or so, in which case if you don't overwrite that things work as you want. If you get lucky and this is the case, you would eventually download the last 1000 bytes, then then start from the front of the file.

It really gets down to finding some way before introducing real networking into the picture, to play a partial file. You will surely find it easier to artificially introduce the networking conditions without really doing it real time.

Answer 3

You gotta create an internal webserver that acts like a proxy! Then set your player to play the movie from the localhost.

When using HTTP protocol to play a video with MPMoviePlayerViewController, the first thing the player does is to ask for the byte-range 0-1 (first 2 bytes) just to obtain the file length. Then, the player asks for "chunks" of the video using the "byte-range" HTTP command (the purpose is to save some battery).

What you have to do is to implement this internal server that delivers the video to the player, but your "proxy" must consider the length of your video as the full length of the file, even if the actual file hasn't been completely downloaded from the internet.

Then you you set your player to play a movie from " http:// localhost : someport "

I've done this before... it works perfectly!

Good luck!