Artwork not showing

[simoncn]

(08-09-2025 14:52)paulr Wrote:  On a general note, is there info around the architecture of this stuff? (i.e. what a upnp server does, what it stores? what does the relevant app do (eg VLC/Naim), what does the app store? What does the player do? what does the player store?). What happens when I open an player app (e.g. VLC and display the library? How does the artwork get to my control point?

There is a 136-page document describing the UPnP architecture. For a very brief summary, see below.

In the UPnP architecture there is a server, a control point and a renderer. These can be dedicated hardware devices or software applications. Sometimes a single device plays multiple roles. The UPnP architecture defines the protocols that the server, control point and renderer use to discover each other on the network and communicate with each other.

The server manages the library and typically runs on the same device that is used to store the library files. It uses the UPnP protocol to communicate with the control point (for browsing the library and providing artwork and metadata from the library) and it uses the HTTP prrotocol for communication with the renderer (for streaming audio files). The server reponds to UPnP requests sent by the control point and HTTP requests sent by the renderer. The server doesn't send any UPNP requests itself.

The control point provides the user interface for browsing the library, showing metadata and artwork and selecting audio files for playing. In traditional UPnP, the server defines the library browsing structure/index and the control point sends UPNP requests to the server to navigate the library. More recently, some control points (for example, LUMIN and JPLAY) download the entire library contents and create their own library browsing structure using this information.

To play a file, the control point sends UPnP requests to the renderer specifying an HTTP URL to use for streaming the file. This URL typically points to the server but this isn't required. This gives the server the opportunity to perform various types of audio processing such as transcoding the audio to a different format or changing the volume level or frequency response curve.

Quote:I'm asking because VLC was VERY quick to show me the contents (seconds), it cant surely have built it's own db/cache that quickly.....

This means VLC is not using a cache for artwork or library contents but is reading this from the server every time (traditional UPnP).