[Savonet-users] Bug? merge_tracks() and/or switch() - Demo Code Included

[Kevin M. <mcq...@sf...>]

Hi Again All:

I have done further research into the behaviour of merge_tracks() and switch().  Either I don't understand the correct behaviour of these constructs, or I have found a bug.  Demo code is attached and documented herein.  I have tried to document the issue clearly, and provided source code.  I hope this will help with resolution of my problem!


BACKGROUND:

I want to use a switch() construct to play an -entire- playlist in normal (i.e. top to bottom) order at a specified time.  I am using merge_tracks() to join the target playlist into a single track.


PLATFORM:

Liquidsoap 1.1.0 running on an Intel machine; Ubuntu 12.10 with all updates applied.


PLAYLIST:

I have the following playlist, named "test.pls", which consists of 4 short .ogg files.  Each .ogg file is a 2-second long item that just contains the spoken audio "Item A", "Item B", "Item C", and "Item D".  The merged audio file will be only about 8 seconds in length.  Here is the playlist file:

$ cat ../playlists/test.pls
/home/kevin/radio/content/test/a.ogg
/home/kevin/radio/content/test/b.ogg
/home/kevin/radio/content/test/c.ogg
/home/kevin/radio/content/test/d.ogg


PROGRAM CODE:

I have written a short test program to play the merged "test.pls" source twice per minute.  Here is my short test program:

$ cat demo.liq
#!/usr/local/bin/liquidsoap

# Logging information:
set("log.file.path","/home/kevin/radio/log/test.log")

# Test: merge tracks of test.pls:
zzz = merge_tracks(playlist.safe(reload_mode="watch", mode="normal", "~/radio/playlists/test.pls"))

radio = mksafe(fallback(track_sensitive=false, [ 
			switch([
			 	({0s}, zzz),
			 	({30s}, zzz)
				])
			]
		))

# Streaming: 
output.icecast(%vorbis,
  host = "localhost", port = 8000,
  password = "donthackme", mount = "vorbis-dev",
  radio)

output.icecast(
  %mp3(bitrate=128),
  host = "localhost", port = 8000,
  password = "donthackme", mount = "mp3-dev",
  radio)


EXPECTED BEHAVIOUR:

I expected that the program would play the entire "test.pls" (items a, b, c, and d.ogg) twice every minute, at 0 seconds and 30 seconds of every minute. I should hear "Item A, Item B, Item C, Item D" for about 8 seconds, starting at 0 seconds; and then again at 30 seconds past each minute.


OBSERVED BEHAVIOUR:

The program plays only 2 items,  "a.ogg" and "b.ogg" at 0 seconds of the minute; then it plays the other two items, "c.ogg" and "d.ogg" at 30 seconds past the minute.  This behaviour continues each minute. 


SUMMARY:

Either I don't understand the LS constructs, or there is a problem either with merge_tracks() or with switch().

I am hoping for the former, as I would like to get my little project completed, but if this is a bug then I hope this information can help resolve it.

I have attached my demo program code.

Any assistance appreciated, I like LS so far and it will meet my project needs perfectly once I get the new program running!

Kevin