How to Serve HLS Video from an S3 Bucket

This post will describe how to configure an S3 bucket to serve video using HLS.

Amazon S3 is a storage solution that allows you to store large amounts of data for relatively little cost, perfect for something like video files, which tend to be quite large. Files (or objects as they are often referred to) are accessed over HTTP, which makes it a great solution for storing (and serving) your HLS videos.

You’ll need an Amazon Web Services (AWS) account to use S3. If you haven’t got one, you can sign up here. Sign in to your account and navigate to the S3 console. Create a bucket. Next, upload your video segments and playlist etc. to the bucket.

Make sure the content type of the playlist and the video segments (.ts) is set to “application/x-mpegURL” and “video/MP2T” respectively. You can do this by selecting the Properties tab for each file and then clicking on Metadata.

Before you can start serving your videos, you need to grant read access to the files in the bucket; files are private by default. Select the Permissions tab and set the bucket policy to the following:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "PublicReadForGetBucketObjects",
            "Effect": "Allow",
            "Principal": "*",
            "Action": "s3:GetObject",
            "Resource": "arn:aws:s3:::<your bucket name>/*"
        }
    ]
}

Most browsers don’t support HLS natively, so HLS video playback is typically achieved by using some sort of Javascript-based video player like Video.js, for example. To play an HLS video all you typically need to do is configure the player with the playlist URL and it takes care of the rest. If you serve your videos from the same domain as the video player, there are no additional steps for you to do. However, for the purposes of this post I’m going to assume the video player references the playlist stored in the S3 bucket.

This presents a bit of a problem. If you request a resource (a file) from a different domain, you need permission to do so; it violates the same-origin policy that browsers enforce. Cross-origin resource sharing (CORS) is a mechanism that allows user agents to request permission to access resources that reside on a different server. In this instance, you need to grant permission to the player to allow it to access to the video(s) in the S3 bucket.

Thankfully, Amazon S3 supports CORS so you can selectively allow cross-origin access to the files in your S3 bucket. To enable CORS on your bucket, select the Permissons tab then click on CORS configuration. By default, the configuration file allows access from anywhere. If I wanted to restrict access to the videos to this domain, I would modify the CORS configuration to look like this:

<?xml version="1.0" encoding="UTF-8"?>
<CORSConfiguration xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
<CORSRule>
   <AllowedOrigin>http://hlsbook.net</AllowedOrigin>
   <AllowedMethod>GET</AllowedMethod>
   <MaxAgeSeconds>3000</MaxAgeSeconds>
   <AllowedHeader>Authorization</AllowedHeader>
</CORSRule>
</CORSConfiguration>

Once you have granted public access to files in the S3 bucket and configured CORS appropriately, you should now be able to serve your HLS videos from an S3 bucket.

Restricting Access

Setting the allowed origin(s) in the CORS policy will prevent somebody from embedding your video on their website if they use a player like VideoJS, but it won’t prevent it if the browser supports HLS natively because in this instance, the same-origin policy doesn’t apply. One thing you can do is check for the presence of the Referer header and if the request hasn’t come from your domain, you block it. You can do this by modifying the bucket policy. Here’s the policy for my bucket:

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "PublicReadForGetBucketObjects",
            "Effect": "Allow",
            "Principal": "*",
            "Action": "s3:GetObject",
            "Resource": "arn:aws:s3:::net.hlsbook/*"
        },
        {
            "Sid": "Explicit deny to ensure requests are allowed only from a specific domain.",
            "Effect": "Deny",
            "Principal": "*",
            "Action": "s3:GetObject",
            "Resource": "arn:aws:s3:::net.hlsbook/*",
            "Condition": {
                "StringNotLike": {
                    "aws:Referer": [
                        "http://hlsbook.net/*"
                    ]
                }
            }
        }
    ]
}

This policy will check the referrer header and if it doesn’t match or it’s missing, access to the requested resource will be blocked. (You could include the check in the allowed action but I prefer to use an explicit deny because it overrides any allows.) However, bear in mind that the check can be circumvented because the referrer header can be spoofed.

Unfortunately, Chrome Mobile doesn’t include the referrer header so the above policy will block access to your videos on that particular browser. Fortunately there is a workaround (or “hack” if you prefer).

The solution is to tell the player to use the Media Source Extensions (if the platform supports it) for HLS playback instead of playing it natively. You can do this with VideoJS by setting the overrideNative property to true. If you view the source for this page, you’ll see this:

videojs.options.hls.overrideNative = true;
videojs.options.html5.nativeAudioTracks = false;
videojs.options.html5.nativeTextTracks = false;

var player = videojs('example-video');
player.src('https://s3.eu-west-2.amazonaws.com/net.hlsbook/prog_index.m3u8');

The referrer header will now be included in the requests so access to the video will no longer be blocked on Chrome Mobile.

One More Thing

HLS playlists support the EXT-X-BYTERANGE tag. This indicates to the player that each video segment is part of a (larger) resource. (There’s more about this in the book if you are interested.) Here’s an example from a playlist that uses the tag:

#EXTM3U
#EXT-X-TARGETDURATION:10
#EXT-X-VERSION:4
#EXT-X-MEDIA-SEQUENCE:0
#EXT-X-PLAYLIST-TYPE:VOD
#EXTINF:10.00000,
#EXT-X-BYTERANGE:808400@0
main.ts
#EXTINF:10.00000,
#EXT-X-BYTERANGE:848068@808400
main.ts
#EXTINF:10.00000,
#EXT-X-BYTERANGE:811784@1656468
main.ts

With the current configuration, any requests for the video file (main.ts) will result in a 403 Access Denied response from S3. To grant access to the file, you need to allow the use of the HTTP Range header. Modify the CORS configuration file so it looks like this:

<?xml version="1.0" encoding="UTF-8"?>
<CORSConfiguration xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
<CORSRule>
   <AllowedOrigin>http://hlsbook.net</AllowedOrigin>
   <AllowedMethod>GET</AllowedMethod>
   <MaxAgeSeconds>3000</MaxAgeSeconds>
   <AllowedHeader>Authorization</AllowedHeader>
   <AllowedHeader>Range</AllowedHeader>
</CORSRule>
</CORSConfiguration>

Now your video player will be able to make range requests for parts of the video file.

Example

Finally, here’s an example of playing an HLS video from an S3 bucket:



Conclusion

Amazon S3 is a cost effective solution for storing videos as video files can take up a lot of space. Because access to files in S3 is over HTTP and with support for CORS, it also makes it a viable solution for using it to serve your HLS videos to your viewers.

S3 also has other features that I haven’t mentioned here, such as versioning and archiving, that could be useful for managing your video assets. Check out the S3 documentation for more information.

11 thoughts on “How to Serve HLS Video from an S3 Bucket

    1. Simon Post author

      Sure. I can’t think of a reason why not. The thing you may want to check is latency: the time it takes to copy the segments from the origin to the bucket. You may want to consider using CloudFront as well.

      Reply
  1. anil v

    Thank you simon,
    But we observed delays in response and the number of requests per second 100 concurrent sessions only supporting.

    Reply
    1. Simon Post author

      You are right, there are limits to how many requests an S3 bucket can serve. (More info here.) If the number of requests you need to serve at any one time exceeds the limit then you’ve answered your original question: you can’t use an S3 bucket for live streams, unless you use a CDN like CloudFront.

      Reply
  2. Leonardo Hammer

    I put m3u8 file and *.ts files into AWS S3, it’s all private. When I pre-signed the m3u8 file, open url, I got error with .ts file, 403 error. How can I fix it? Thanks help.

    Reply
    1. Simon Post author

      This is to be expected. If the bucket is private, you will need to create pre-signed URLs for each .ts file as well as the m3u8 file; otherwise, you will get 403 errors.

      An alternative solution is to encrypt the .ts files, put them in a public bucket, then generate a pre-signed URL for the decryption key. The advantage to this approach is that you only have to create a pre-signed URL for the playlist and the decryption key and not every .ts file.

      Reply
  3. Betty

    When i open this page on my Android and Mobile Chrome 72, this video cannot be loaded. This is only on Android/Chrome. Does anyone have the same problem?

    Reply
    1. Simon Post author

      It should work now. I’d included a check for the referrer header in the bucket policy to prevent hotlinking. After looking at the access logs, it appears that Mobile Chrome 72 doesn’t include this header in the request so access to the files was denied.

      Reply
        1. Simon Post author

          I’ve updated the article to include the bucket policy with the referrer header check and also a workaround for Chrome Mobile.

          Reply

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