[docs] Add README_RADIO_STREAMS.md

Credit @sfeakes

Makefile.am

@@ -20,6 +20,7 @@ nobase_dist_doc_DATA = \
 	README_ALSA.md \
 	README_SMARTPL.md \
 	README_PLAYER_WEBINTERFACE.md \
+	README_RADIO_STREAMS.md \
 	scripts/pairinghelper.sh
 
 EXTRA_DIST = \

README.md

@@ -323,6 +323,10 @@ forked-daapd has support for smart playlists. How to create a smart playlist is
 documented in
 [README_SMARTPL.md](https://github.com/ejurgensen/forked-daapd/blob/master/README_SMARTPL.md).
 
+If you're not satisfied with internet radio metadata that forked-daapd shows,
+then you can read about tweaking it in
+[README_RADIO_STREAMS.md](https://github.com/ejurgensen/forked-daapd/blob/master/README_RADIO_STREAMS.md).
+
 
 ## Artwork
 

README_RADIO_STREAMS.md

@@ -0,0 +1,97 @@
+# forked-daapd and Radio Stream tweaking
+
+Radio streams have many different ways in how metadata is sent.  Many should
+just work as expected, but a few may require some tweaking. If you are not
+seeing expected title, track, artist, artwork in forked-daapd clients or web UI,
+the following may help.
+
+First, understand what and how the particular stream is sending information.
+ffprobe is a command that can be used to interegrate most of the stream
+information. `ffprobe <http://stream.url>` should give you some useful output,
+look at the Metadata section, below is an example.
+
+```
+ Metadata:
+    icy-br          : 320
+    icy-description : DJ-mixed blend of modern and classic rock, electronica, world music, and more. Always 100% commercial-free
+    icy-genre       : Eclectic
+    icy-name        : Radio Paradise (320k aac)
+    icy-pub         : 1
+    icy-url         : https://radioparadise.com
+    StreamTitle     : Depeche Mode - Strangelove
+    StreamUrl       : http://img.radioparadise.com/covers/l/B000002LCI.jpg
+```
+
+In the example above, all tags are populated with correct information, no
+modifications to forked-daapd configuration should be needed. Note that
+StreamUrl points to the artwork image file.
+
+
+Below is another example that will require some tweaks to forked-daapd, Notice
+`icy-name` is blank and `StreamUrl` doesn't point to an image.
+
+```
+Metadata:
+    icy-br          : 127
+    icy-pub         : 0
+    icy-description : Unspecified description
+    icy-url         : 
+    icy-genre       : various
+    icy-name        : 
+    StreamTitle     : Pour Some Sugar On Me - Def Leppard
+    StreamUrl       : https://radio.stream.domain/api9/eventdata/49790578
+```
+
+In the above, first fix is the blank name, second is the image artwork.
+### 1) Stream Name/Title
+Set the name with an EXTINF tag in the m3u playlist file:
+
+```
+#EXTM3U
+#EXTINF:-1, - My Radio Stream Name
+http://radio.stream.domain/stream.url
+```
+
+The format is basically `#EXTINF:<length>, <Artist Name> - <Artist Title>`.
+Length is -1 since it's a stream, `<Artist Name>` was left blank since
+`StreamTitle` is accurate in the Metadata but `<Artist Title>` was set to
+`My Radio Stream Name` since `icy-name` was blank.
+
+### 2) Artwork (and track duration)
+If `StreamUrl` does not point directly to an artwork file then the link may be
+to a json file that contains an artwork link. If so, you can make forked-daapd
+download the file automatically and search for an artwork link, and also track
+duration.
+
+Try to download the file, e.g. with `curl "https://radio.stream.domain/api9/eventdata/49790578"`.
+Let's assume you get something like this:
+
+```
+{
+    "eventId": 49793707,
+    "eventStart": "2020-05-08 16:23:03",
+    "eventFinish": "2020-05-08 16:27:21",
+    "eventDuration": 254,
+    "eventType": "Song",
+    "eventSongTitle": "Pour Some Sugar On Me",
+    "eventSongArtist": "Def Leppard",
+    "eventImageUrl": "https://radio.stream.domain/artist/1-1/320x320/562.jpg?ver=1465083491",
+    "eventImageUrlSmall": "https://radio.stream.domain/artist/1-1/160x160/562.jpg?ver=1465083491",
+    "eventAppleMusicUrl": "https://geo.itunes.apple.com/dk/album/530707298?i=530707313"
+}
+```
+
+In this case, you would need to tell forked-daapd to look for "eventDuration"
+and "eventImageUrl" (or just "duration" and "url"). You can do that like this:
+
+```
+curl -X PUT "http://localhost:3689/api/settings/misc/streamurl_keywords_length" --data "{\"name\":\"streamurl_keywords_length\",\"value\":\"duration\"}"
+curl -X PUT "http://localhost:3689/api/settings/misc/streamurl_keywords_artwork_url" --data "{\"name\":\"streamurl_keywords_artwork_url\",\"value\":\"url\"}
+```
+
+If you want multiple search phrases then comma separate, e.g. "duration,length".
+
+
+If your radio station is not returning any artwork links, you can also just make
+a static artwork by placing a png/jpg in the same directory as the m3u, and with
+the same name, e.g. `My Radio Stream.jpg` for `My Radio Stream.m3u`.