Open Source Projects Europe

== Upmpdcli Media Server: streaming services

[[UPRCL]]

== Upmpdcli local Media Server: uprcl

The current (2017-04) upmpdcli code base includes a Media Server function

for local music files, analog to MinimServer or ReadyMedia/MiniDLNA. The

plugin module is named uprcl.

Why yet another Media Server ? MinimServer is great, and free, but not

open-source. ReadyMedia is nice too, but audio file format support is

incomplete (there was a patch for DSD but it was never merged apparently),

I've always found it a bit clunky (for example: no incremental updates),

and development does not seem very active.

The new upmpdcli Media Server is at most beta quality. It probably has even

less format support than MiniDLNA... But it's written in Python, and I have

good hope that it can evolve faster.

Some features:

- Mostly written in Python, except for the pieces shared with the streaming

  plugins: UPnP interface proper, and plugin management, which are C++, but

  should not need a lot of changes.

- Tries to mimick the MinimServer tree view, which I find quite nice. We're

  not quite there yet, many functions and niceties, and the customization

  capability are missing.

- Uses Recoll and python-recoll (hence the uprcl name) for harvesting the

  metadata and searching. Recoll already had almost everything needed in

  this area, no development needed. It can perform incremental updates and

  file system monitoring.

- Uses Python sqlite3 (on a memory DB) for the tags tree. 

Installation and configuration: have a look at the

xref:uprcluser[configuration variables]

[[UPRCL-SEARCH]]

=== Upmpdcli/Uprcl searches

The UPnP Media Server search function is based on a specific query

language. This language is quite verbose, and most control points will not

let you access it directly. Instead, they will usually provide a generic

entry field in which you enter search terms.  Behind the scenes, they

generate an UPnP search language string. This could be for example

something like: `upnp:class = "object.item.audioItem" and dc:title

contains "heaven"`

If it supports search at all, the Media Server will then interpret the

query string and return the results.

If the Media Server is Upmpdcli/Uprcl, there is another step: the UPnP

query string is translated into a Recoll one and Recoll is called to

perform the actual search. There is no way to directly enter a Recoll

search through the control point. However, two important Recoll

capabilities should still be visible through the layers:

.Stemming

Stemming is the capability to expand a search to the common derivatives of

a word. For example, a search for `floor` would be expanded to also look

for `floors`, `flooring`, `floored`, etc. By default, stemming is enabled

for Uprcl search. It can be turned off for any term by capitalizing the

term (Entering `Stones` will only search for `stones`, not `stone` or

`stoned`). Uprcl/Recoll searches are case-insensitive apart from this usage

of capitalization.

.Phrase searches

By default, Uprcl/Recoll searches do not observe the order

of terms: `red house` will be matched by a search for `house red` (or

`houses red`). You can change this behaviour by quoting a sequence of

words. A search for `"red house"` will only look for a text containing the

words in order. This supposes that the Control Point does not change the

user entry, but this is the case for at least some of them. Stemming

expansion does not occur within phrase searches.

Other Recoll capabilities, such as proximity searches should also be

accessible, but probably less useful when searching music titles or artist

names.