R2-Kotlin: play audio Epub content using local server

[nareshsvn]

In R1, We used to play the audio epub using exo-player(native player) by starting EpubServer.
Start Server:
EpubServer mServer = new EpubServer(EpubServer.HTTP_HOST, EpubServer.HTTP_PORT,
mContainer.getDefaultPackage(), false, null, getApplicationContext());
mServer.setAudioPlayingStatus();
mServer.startServer();

After starting the server, we used to supply the url( mContainer.getDefaultPackage().getManifestItem(position).getHref()) to the exo-player. now exo-player plays locally. (Epub server acts as a local server and exo-payer will communicate using url "http://127.0.0.1:8080/track1")

In R2 is there a way we can achieve the same behavior(we need to use a native player to give more controls)?

[mickael-menu]

In R2 (at the moment) resources are also served through an HTTP server, so you can also use it to provide URLs to ExoPlayer.

In the Readium Web Publication models used in R2, readingOrder will contain the Link to the EPUB chapters, while resources should contain CSS, JavaScript and also audio files. So you can use the following to get the list of audio files referenced in the EPUB:

val audioLinks = publication.resources.filter { it.mediaType.isAudio }

Then you can concatenate the base URL used to serve the publication on the server when adding the publication to the link's href to get the full URL:

val baseUrl = Publication.localBaseUrlOf(publicationFilename, server.port)
val url = baseUrl + audioLinks[0].href

[mickael-menu]

However, my preferred approach would be to use ExoPlayer's DataSource to implement reading directly the content of a publication using our Resource API. This doesn't require an HTTP server.

I implemented it in this WIP Audiobook navigator PR.

Take a look in particular at PublicationDataSource and how it's used in the PR:

https://github.com/readium/r2-navigator-kotlin/pull/160/files#diff-50505037106ff838f537dab8e101b8f922a51e4eff71ccc87f9857e7d8228f7e