The audio file selector ======================= Paraslash comes with a sophisticated audio file selector called afs. In the << installation notes, >> only the "dummy" mode of afs was used which gets activated automatically if nothing else was specified. In this section the various features of afs are described. ---------- Attributes ~~~~~~~~~~ An attribute is simply a bit which can be set for each audio file individually. Up to 64 different attributes may be defined. For example, "pop", "rock", "blues", "jazz", "instrumental", "german_lyrics", "speech", whatever. It's up to you how many attributes you define and how you call them. A new attribute "test" is created by para_client addatt test and para_client lsatt lists all available attributes. You can set the "test" attribute for an audio file by executing para_client setatt test+ /path/to/the/audio/file Similarly, the "test" bit can be removed from a audio file with para_client setatt test- /path/to/the/audio/file Instead of a path you can also use a pattern, and the attribute is applied to all audio files matching that pattern: para_client setatt test+ '/test/directory/*' The command para_client -- ls -lv gives you a verbose listing of your audio files which contains also which attributes are set. In case you wonder why the double-dash in the above command is needed: It tells para_client to not interpret the options after the dashes. If you find this annoying, just say alias para='para_client --' and be happy. In the remainder part this alias is being used. Drop the test attribute entirely from the database with para rmatt test Read the output of para help ls para help setatt for more information and a complete list of command line options to these commands. ---------------------- Abstract mood nonsense ~~~~~~~~~~~~~~~~~~~~~~ [skip this part if you don't like formal definitions] A mood consists of a unique name and its *mood definition*, which is a set of *mood lines* containing expressions in terms of attributes and other data contained in the database. A mood defines a subset of audio files called the *admissible audio files* for that mood. A mood can be *active* which means that para_server is going to select only files from that subset of admissible files. So in order to create a mood definition one has to write a set of mood lines. Mood lines come in three flavours: Accept lines, deny lines and score lines. The general syntax of the three types of mood lines is accept [with score ] [if] [not] [options] deny [with score ] [if] [not] [options] score [if] [not] [options] Here is either an integer or the string "random" which assigns a random score to all matching files. The score value changes the order in which admissible files are going to be selected, but is of minor importance for this introduction. So we concentrate on the first two forms, that is accept and deny lines. As usual, everything in square brackets is optional, i.e. accept/deny lines take the following form when ignoring scores: accept [if] [not] [options] and analogously for the deny case. The "if" keyword is purely cosmetic and has no function. The "not" keyword just inverts the result, so the essence of a mood line is the mood method part and the options following thereafter. A *mood method* is realized as a function which takes an audio file and computes a number from the data contained in the database. If this number is non-negative, we say the file *matches* the mood method. The file matches the full mood line if it either - matches the mood method and the "not" keyword is not given, or - does not match the mood method, but the "not" keyword is given. The set of admissible files for the whole mood is now defined as those files which match at least one accept mood line, but no deny mood line. More formally, a file is admissible if and only if (F ~ AL1 or F ~ AL2...) and not (F ~ DL1 or F ~ DN2 ...) where F is the file, AL1, AL2... are the accept lines, DL1, DL2... are the deny lines and "~" means "matches". The cases where no mood lines of accept/deny type are defined need special treatment: - Neither accept nor deny lines: This treats all files as admissible (in fact, that is the definition of the dummy mood which is activated automatically if no moods are available). - Only accept lines: A file is admissible iff it matches at least one accept line: F ~ AL1 or F ~ AL2 or ... - Only deny lines: A file is admissible iff it matches no deny line: not (F ~ DL1 or F ~ DN2 ...) -------------------- List of mood_methods ~~~~~~~~~~~~~~~~~~~~ no_attributes_set Takes no arguments and matches an audio file if and only if no attributes are set. played_rarely Takes no arguments and matches all audio files where the number of times this audio file was selected is below the average. is_set attribute_name Takes the name of an attribute and matches iff that attribute is set. path_matches pattern Takes a filename pattern and matches iff the path of the audio file matches the pattern. ---------- Mood usage ~~~~~~~~~~ To create a new mood called "my_mood", write its definition into some temporary file, say "tmpfile", and add it to the mood table by executing para addmood my_mood < tmpfile If the mood definition is really short, you may just pipe it to the client instead of using temporary files. Like this: echo "$MOOD_DEFINITION" | para addmood my_mood There is no need to keep the temporary file since you can always use the catmood command to get it back: para catmood my_mood A mood can be activated by executing para chmood my_mood Once active, the list of admissible files is shown by the ls command if the "-a" switch is given: para ls -a ----------------------- Example mood definition ~~~~~~~~~~~~~~~~~~~~~~~ Suppose you have defined attributes "punk" and "rock" and want to define a mood containing only Punk-Rock songs. That is, an audio file should be admissible if and only if both attributes are set. Since punk and rock is obviously the same as not (not punk or not rock) (de Morgan's rule), a mood definition that selects only Punk-Rock songs is deny if not is_set punk deny if not is_set rock --------- Troubles? --------- Use loglevel one (option -l 1 for most commands) to show debugging info. Almost all paraslash executables have a brief online help which is displayed by using the -h switch. para_fsck tries to fix your database. Use --force (even if your name isn't Luke), to clean up after a crash. However, first make sure para_server isn't running before executing para_fsck if para_fsck complains about busy (dirty) tables. para_fsck also contains an option to dump the contents of your the contents of the database to the file system. If you don't mind to recreate your database you can start from scratch by removing the entire database directory, i.e. rm -rf ~/.paraslash/afs_database Note that this removes all tables, in particular attribute definitions and data, and all playlist and mood definitions. para_fsck operates on the osl-layer, i.e. it fixes inconsistencies in the database but doesn't know about the contents of the tables contained therein. Use para_client check to print out bad entries, e.g.missing audio files or invalid mood definitions. Still having problems? mailto: Andre Noll