#Hls Streaming How To Create And#
#Hls Streaming Offline HLS Starts#
#Hls Streaming Download HLS Back#

Hls Streaming Download HLS Back

Over the years we have added new functionality and in this talk we'll cover everything you need to know. We introduced the ability to download HLS back in 2016. If you are looking to let your users download and play your HLS content while off line, you've tuned in to the right session. As of 2019, an annual video industry survey has consistently found it to be the most popular streaming format.My name is Nishant and I am a Streaming Media Engineer at Apple. Support for the protocol is widespread in media players, web browsers, mobile devices, and streaming media servers. HTTP Live Streaming (also known as HLS) is an HTTP-based adaptive bitrate streaming communications protocol developed by Apple Inc.

They may want to download say when they're about to get on an airplane, or they may be on some expensive cellular data dataplan and they may want to download on Wi-Fi, in all these cases. Use it when your user explicitly requests media downloads. So first question first, should I use offline HLS? Yes. And finally offline HLS allows your users to download the content in the background. Along with that you can use FairPlay streaming content protection. You can use the same for downloads.

Hls Streaming Offline HLS Starts

Later on, you need to monitor the download task and update any progress in your app. The download task represents the entire lifecycle of a media download such as a movie. Offline HLS starts with the creation of a download task. Let's see how we can get you started.

If the index is detected, the action button will become active and therefore the direct download - possible.Download tasks are defined on URLSession. For the general HLS (HTTP Live Streaming), downloading the video directly is possible only if the video index can be detected. But also supports adaptive streaming formats such as HLS and DASH.Stream Recorder has two main operation modes - Normal and Capture. So let's take a look at the download task.It supports HTML5 video and modern streaming formats, as well as YouTube, Vimeo.

The first one we're going to look at is AVAssetDownloadTask. Coming to download tasks, there are two variants. Before we dig in, let's take a look at typical HLS asset we all are a familiar with.This particular asset has a bunch of video, audio and subtitle renditions.We will be using this as an example going forward. For example, if you hit network timeouts, AVFoundation retries the download for you. Another important thing to remember is that downloads are automatically retried.

And then once you have the URLSession you can call makeAssetDownloadTask. You create it with the session configuration using an identifier. To create one of these download tasks, you need to set up a URLSession specifically AVAssetDownloadURLSession.

For example if the device region is set as France, French audio and French subtitle renditions will be downloaded. What does that mean? Automatic media selection chooses renditions based on device region and localization preferences. When you create AVAssetDownloadTask automatic media selection will be used.

I wouldn't go into detail but it's here for your reference. Here is an example on how you can do it. We also have didCompleteWithError, which informs you when the download is complete.You can use these interfaces to build a progress UI in your app. It provides you that with the time ranges that have been downloaded rather than bytes, so as to correlate better with media interfaces. I would like to highlight two of the interfaces we have here.The first one can be used to monitor the progress of your download. To do this you need to use AVAssetDownloadDelegate protocol.

Going back to our earlier example using AggregateDownloadTask, You can download English audio and English subtitles followed by Spanish audio and Spanish subtitles and French subtitle renditions.This API is appropriate when you want to let your users choose which audio and subtitle renditions they want to download. Using AVAggregateAssetDownloadTask, you choose what renditions you want to download. We have another API called AVAggregateAssetDownloadTask.

The first thing to do is split the download progress between your various media selections. Since AggregateAssetDownloadTask involves multiple media selections, monitoring it is a bit different compared to AVAssetDownloadTask. Later, you call aggregate AggregateAssetDownloadTask with the media selections you wanted to download. Once you have your media selections you create AVAssetDownloadURLSession as we did before. You can create a media selection by opening a mutableMediaSelection from your asset and choosing appropriate media selection option.

You can assign 70 percent of the download time to the video rendition, 10 percent of the time to each of the audio renditions. Keep in mind that downloading audio takes more time compared to downloading subtitle tracks.Going back to our earlier example. Then you split the remaining weight between your other media selections. We have observed that this accounts for approximately 70 percent of the download time, but this may vary depending on how your content is authored. The first media selection will typically involve downloading video and hence will take a longer time.

Another interface to look at as didCompleteForMediaSelection. But here, in addition to loadedTimeRanges you will be informed about the media selection for which the time range was loaded. Similarly to AVAssetDownloadTask. To monitor progress, you still use the loadedTimeRanges callback. In order to get you started, let's look at some of the downloadDelegate interfaces. Finally we can assign the remaining time to the subtitle renditions.

Download tasks still run when your app is in background. Another thing that might happen during their download is your app may get backgrounded. In case of audio rendition, expect the calls twice: once for studio representation, followed by once far multi-channel representation.

Hls Streaming How To Create And

So now you know how to create and monitor the download task. Then you can restore your existing task and then query the task to get the latest status of your downloads.You can also get the original AVAsset from the downloadTkask and you use it. You can do this by creating a URLSession with the same configuration identifier you used previously.

We'll see that reason in a bit. And in case of aggregateDownloadTask, you get the location via willDownloadTo delegate callback.We may want to store this location. In case of AVAssetDownloadTask, you get the location once the download is complete. First let's take a look at where your download is deposited on the disk.

Now you know how to download and play media content while offline. And also what media selections are playable offline. It tells you what can we play it offline. We can obtain the AVAssetCache object from your AVAsset. Some of you may be wondering, Alright, I have an asset here probably with a bunch of audio and subtitled renditions, How can I find out what can be played offline? We have an interface called AVAssetCache.

If you're new to FairPlay streaming I would recommend you check out our earlier talk 'AVContentKeySession Best Practices' from WWDC 2018. You can do the same for offline HLS as well. FairPlay streaming for offline HLS was introduced back in 2016.Some of you may already be using FairPlay Streaming for protecting your streaming content.

Let's see how we can get to this offline key. Instead you create something called as offline key during the download and store it for later use. You may not be able to reach your key server.

And provide the CKC to AVContentKeySession. You call your key server and get back the key in the form of Content Key Context. Then you create a server playback context, SPC for short, by providing your FairPlay streaming application certificate. When you create the downloadTask you will also receive a key request from AVContentKeySession, If the key is already not loaded. Then, initiate key loading as you normally do for the streaming case.If you do not know the key required for the download, don't worry.

We store there offline key for subsequent use.