Question 69140 in IOS Swift Question posted in
The official documentation can be found here.

How can I stream MP4 videos from S3 without AVPlayer downloading the files before playing them? – Ios swift

I have a lot of long (45 mins – 90 mins) MP4 videos in a public S3 bucket and I want to play them in my iOS app using AVPlayer.

I am using AVPlayerViewController to play them but I need to wait several minutes before they start playing as it downloads the whole video rather than streaming it.

I am caching it locally so this is only happening the first time but I would love to stream the video so the user doesn’t have to wait for the entire video to download.

Some people are pointing out that I need Cloudfront to stream videos but in the documentation, I’ve read that this is only necessary when you have many people streaming the same file. I’m building a MVP so I only need a simple solution.

Is there any way to stream an MP4 video from an S3 bucket with AVPlayerViewController without it fully downloading the file before playing it to the user?

Tags:

2

Answers


  1. 0

    TLDR

    AVPlayer does not support ‘streaming’ (HTTP range requests) as you would define it, so either use an alternative video player that does or use a real media streaming protocol like HLS which is supported by AVPlayer & would start the video before downloading it all.

    CloudFront is great for delivery in general but is not truly needed – you may have seen it mentioned due to CloudFront RTMP distributions but they now have been discontinued.

    Detailed Answer

    S3 supports a concept called byte-range fetches using HTTP range requests – you can verify this by doing a HEAD request to your video file & seeing that the Accept-Ranges header exists with a value set to bytes (or not ‘none’).

    Load your MP4 file in the browser & notice that it can start as soon as you click play. You’re also able to move to the end of the video file and yet, you haven’t really downloaded the entire video file. HTTP range requests are what allow this mechanism to work. Small chunks of the video can be downloaded as & when the user gets to that part of the video. This saves the file server & the user bandwidth while providing a much better user experience than the client downloading the entire file.

    The server would need to support byte-range fetches in the first instance before the client can then decide to make range requests (or not to). The key is that, once the server supports it, it is up to the HTTP client to decide whether it wants to fetch the data in chunks or all in one go.

    This isn’t really ‘streaming’ as you know it & are referring to in your question but it is more ‘downloading the video from the server in chunks and playing it back’ using HTTP 206 Partial Content responses.

    You can see this in the Network tab of your browser as a series of multiple 206 responses when seeking in the video. The entire video is not downloaded but the video is streamed from whichever position that you skip to.

    image showing multiple HTTP 206 Partial Content responses in the network tab of Google Chrome when loading a video in browser and moving to random points in the video; highlights HTTP range requests

    The problem with AVPlayer

    Unfortunately, AVPlayer does not support ‘streaming’ using HTTP range requests & HTTP 206 Partial Content responses. I’ve verified this manually by creating a demo iOS app in Xcode.

    This has nothing to do with S3 – if you stored these files on any other cloud provider or file server, you’d see that the file is still fully loaded before playing.

    The possible solutions

    Now that the problem is clear, there are 2 solutions.

    Using an alternative video player

    The easiest solution is to use an alternative video player which does support byte-range fetches. I’m not an expert in iOS development so I sadly can’t help in recommending an alternative but I’m sure there’ll be a popular library that the industry prefers over the in-built AVPlayer. This would provide you with your (extremely common) definition of ‘streaming’.

    Using a video streaming protocol

    However, if you must use AVPlayer, the solution is to implement true media streaming with a video streaming protocol – true streaming also allows you to leverage features like adaptive bitrate switching, live audio switching, licensing etc.

    There are quite a few of these protocols available like DASH (Dynamic Adaptive Streaming over HTTP), SRT (Secure Reliable Transport) & last but not least, HLS (HTTP Live Streaming).

    Today, the most widely used streaming protocol on the internet is HLS, created by Apple themselves (hey, maybe the reason to not support range requests is to force you to use the protocol). Apple’s own documentation is really wonderful for delving deeper if you are interested.

    Without getting too much into protocol detail, HLS will allow playback to start more quickly in general, fast-forwarding can be much quicker & delivers video as it is being watched for the true streaming experience.

    To go ahead with HLS:

    1. Use AWS Elemental MediaConvert to convert your MP4 file to HLS format – the resulting output will be 1 (or more) .M3U8 manifest files in addition to .ts media segment file(s)

    2. Upload the resulting output to S3

    3. Point AVPlayer to the .M3U8 file

    let asset = AVURLAsset(url: "https://ermiya.s3.eu-west-1.amazonaws.com/videos/video1playlist.m3u8")
let item = AVPlayerItem(asset: asset)
...
    1. Enjoy near-instant loading of the video

    CloudFront

    In regards to Amazon CloudFront, it isn’t required per se & S3 is sufficient in this case but a quick Google search will mention loads of benefits that it provides, especially caching which can help you save on S3 costs later on.

    Conclusion

    I would go with converting to HLS if you can, as it will yield more possibilities down the line & is a better true streaming experience in general, but using an alternative video player will work just as well due to iOS AVPlayer restrictions.

    Whether to use CloudFront or not, will depend on your user base, usage of S3 and other factors.

    As you’re creating an MVP, I would recommend just doing a batch conversion of your MP4 files to HLS format & not using CloudFront which would add additional complexity to your cloud configuration.

    Login or Signup to reply.
  2. 0

    Like @ErmiyaEskandary said, you could just use HLS to solve your problem, which is probably a good idea, but you should not have to wait for the entire MP4 file to download before playing it with AVPlayer. The issue is actually not with AVPlayer or byte-range requests at all, but rather with how your MP4 files are formatted.

    You could have your MP4 file configured incorrectly for streaming. MP4’s have a metadata section called the MOOV atom. By default, many encoders put this at the back of the file. In this case, the player would have to download the entire file before it could begin playing.

    For streaming usecases, this would need to be put at the front of the file. The player then will only need to buffer the MOOV atom, and it can begin playing the video as the data is loaded.

    You can use ffmpeg with the fast start flag enabled to move the MOOV atom to the beginning of the file.

    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search