[ExoPlayer] Using MergingDataSource

I'm using AndroidVideoCache v2.7.0 and ExoPlayer v2.4.1, I have no trouble playing & caching a **single** media, however, I can't find a way to cache two medias (audio & video) at the same time.

To get into the details, I'm retrieving the URLs of the audio and video medias separately, I tried to cache both medias at the same time but it would then throw an IllegalStateException when passing the URI to ExoPlayer. Removing the cache functionality, passing both URI to ExoPlayer with MergingMediaSource works well and no errors are thrown.

So i'm starting to guess AndroidVideoCache cannot cache two or more medias at the same time. I dived a bit into the code and noticed the library open a single socket bound to the local address per instance. Even if I tried to create 2 instances of HttpProxyCacheServer, it doesn't work aswell.

Comienza reproduciendo el caso de dos medios con AndroidVideoCache v2.7.0 y ExoPlayer v2.4.1, usando URLs independientes de audio y vídeo con MergingMediaSource. Inspecciona HttpProxyCacheServer y la IllegalStateException informada; después, determina si se admite el almacenamiento en caché simultáneo; se considera terminado cuando el comportamiento se haya corregido o se haya establecido claramente su limitación.

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