Custom URL loader

[Type1J]

Hello,

I have a desktop app with a webview.

The native app gives me access to video and audio segments, as well as information that I can use to construct a DASH manifest.

I think that using a base URL in the manifest with a custom scheme (i.e. my_custom_scheme://video/42.m4s) is what would make dash.js use some sort of plugin loader for the segments, and maybe the manifest as well.

The extensions to dash.js that I've seen have only modified a request that already has an XHR, etc., and I don't need an XHR since I'm not making a network request, just a call to the native app through functions that it provides to the web view. The other extension that I've seen is for indexed DB offline, and it looks much more involved than what I believe is needed: I just want dash to call a function that I make with an URL, and have that function return an ArrayBuffer/Uint8Array of the segment, and maybe headers, if that's needed by dash.js.

I'd also like to load the manifest with the custom scheme if possible.

I feel like there's already something in place that allows me to make such an plugin, but I haven't seen any documentation about it.

What do I need to do to make this plugin and register it with dash.js?

[bbert]

Yes there is something in place but I'm not sure if it is really possible to register a plugin from the application.
It is used inside dash.js by the OfflineController to enable segments fetching from local indexedDB storage, but don't know about other implementations.
Moreover the mechanism in place is not complete in my opinion since some points are missing such as a mechanism to enable the plugin to notify the dash.js core layer about the download progress.
@dsilhavy maybe we could add this functionnality in the scope of the 5.0 version?

[Type1J]

I saw the offline directory, but it has quite a few files, and I'm not sure where to start reading it. Does that mean that I will need to do something similar and compile a custom version of dash.js to make it work?

I don't think that progress is needed in my case, since segments are small, and ussually come in a few hundred nanoseconds.

[bbert]

I guess yes you'll have to compile a custom version.
Another way is to extend and override the XHRLoader class.
But I would definitely be in favor of having a scheme plugin mechanism as proposed by some other player.

[Type1J]

Thanks for your responses!

I guess I have to wait until @dsilhavy reponds to know if there's an expected way to use a custom loader. I'll look at the XHRLoader class in the meantime.

[dsilhavy]

At this point, I am not planning to implement support for custom loaders. There are issues with higher priorities at this point. If you can work on this, I am happy to review a pull request or a first architecture draft/idea.

[Type1J]

I'm not too familiar with the codebase at this point, but I need this functionality soon, even if I have to hack it together. Once I have it working, I'll try to make it more polished, and match the codebase style for a PR.

[dsilhavy]

Thanks this sounds good