In addition to the three network streaming modes, para_recv can also
operate in local (afh) mode. In this mode it writes the content of
an audio file on the local file system in complete chunks to stdout,
-optionally 'just in time'. This allows to cut an audio file without
-first decoding it, and it enables third-party software which is unaware
-of the particular audio format to send complete frames in real time.
+optionally 'just in time'. This allows cutting audio files without
+decoding, and it enables third-party software which is unaware of
+the particular audio format to send complete frames in real time.
<h3> para_filter </h3>
cd osl && make && sudo make install && sudo ldconfig
sudo apt-get install autoconf libssl-dev m4 \
libmad0-dev libid3tag0-dev libasound2-dev libvorbis-dev \
- libfaad-dev libspeex-dev libFLAC-dev libsamplerate-dev realpath \
+ libfaad-dev libspeex-dev libflac-dev libsamplerate-dev \
libasound2-dev libao-dev libreadline-dev libncurses-dev \
libopus-dev
git clone git://git.tuebingen.mpg.de/osl
-- [openssl](http://www.openssl.org/) or
+- [openssl](https://www.openssl.org/) or
[libgcrypt](ftp://ftp.gnupg.org/gcrypt/libgcrypt/). At least one
of these two libraries is needed as the backend for cryptographic
routines on both the server and the client side. Both openssl and
to install the development package (`libssl-dev` or `libgcrypt-dev`
on debian systems) as well.
+- [flex](https://github.com/westes/flex) and
+[bison](https://www.gnu.org/software/bison) are needed to build the
+mood parser of para_server. The build system will skip para_server
+if these tools are not installed.
+
- [libmad](http://www.underbit.com/products/mad/). To compile in MP3
support for paraslash, the development package must be installed. It
is called `libmad0-dev` on debian-based systems. Note that libmad is
not necessary on the server side, i.e., for sending MP3 files.
- [libid3tag](http://www.underbit.com/products/mad/). For version-2
-ID3 tag support, you willl need the libid3tag development package
+ID3 tag support, you will need the libid3tag development package
`libid3tag0-dev`. Without libid3tag, only version-1 tags are
recognized. The mp3 tagger also needs this library for modifying
(id3v1 and id3v2) tags.
-- [ogg vorbis](http://www.xiph.org/downloads/). For ogg vorbis streams
+- [ogg vorbis](https://www.xiph.org/downloads/). For ogg vorbis streams
you need libogg, libvorbis, libvorbisfile. The corresponding Debian
packages are called `libogg-dev` and `libvorbis-dev`.
-- [libfaad and mp4ff](http://www.audiocoding.com/). For aac files
+- [libfaad and mp4ff](https://sourceforge.net/projects/faac/). For aac files
(m4a) you need libfaad and libmp4ff (package: `libfaad-dev`). Note
that for some distributions, e.g. Ubuntu, mp4ff is not part of the
libfaad package. Install the faad library from sources (available
through the above link) to get the mp4ff library and header files.
-- [speex](http://www.speex.org/). In order to stream or decode speex
+- [speex](https://www.speex.org/). In order to stream or decode speex
files, libspeex (`libspeex-dev`) is required.
-- [flac](http://flac.sourceforge.net/). To stream or decode files
+- [flac](https://xiph.org/flac/). To stream or decode files
encoded with the _Free Lossless Audio Codec_, libFLAC (`libFLAC-dev`)
must be installed.
- [alsa-lib](ftp://ftp.alsa-project.org/pub/lib/). On Linux, you will
need to have the ALSA development package `libasound2-dev` installed.
-- [libao](http://downloads.xiph.org/releases/ao/). Needed to build
+- [libao](https://ftp.osuosl.org/pub/xiph/releases/ao/). Needed to build
the ao writer (ESD, PulseAudio,...). Debian package: `libao-dev`.
- [curses](ftp://ftp.gnu.org/pub/gnu/ncurses). Needed for
Next, change to the "bar" account on client_host and generate the
key pair with the commands
- ssh-keygen -q -t rsa -b 2048 -N '' -f $key
+ ssh-keygen -q -t rsa -b 2048 -N '' -m RFC4716
This generates the two files id_rsa and id_rsa.pub in ~/.ssh. Note
that para_server won't accept keys shorter than 2048 bits. Moreover,
<h3> Moods </h3>
-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.
-
-At any time at most one 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 <score>] [if] [not] <mood_method> [options]
- deny [with score <score>] [if] [not] <mood_method> [options]
- score <score> [if] [not] <mood_method> [options]
-
-
-Here <score> 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, i.e. 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] <mood_method> [options]
-
-and analogously for the deny case. The "if" keyword is only syntactic
-sugar 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, an audio file F is admissible if and only if
-
- (F ~ AL1 or F ~ AL2...) and not (F ~ DL1 or F ~ DN2 ...)
-
-where 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 ...)
-
-
-
-<h3> List of mood_methods </h3>
-
- no_attributes_set
-
-Takes no arguments and matches an audio file if and only if no
-attributes are set.
-
- 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.
-
- artist_matches <pattern>
- album_matches <pattern>
- title_matches <pattern>
- comment_matches <pattern>
-
-Takes an extended regular expression and matches iff the text of the
-corresponding tag of the audio file matches the pattern. If the tag
-is not set, the empty string is matched against the pattern.
-
- year ~ <num>
- bitrate ~ <num>
- frequency ~ <num>
- channels ~ <num>
- num_played ~ <num>
- image_id ~ <num>
- lyrics_id ~ <num>
-
-Takes a comparator ~ of the set {<, =, <=, >, >=, !=} and a number
-<num>. Matches an audio file iff the condition <val> ~ <num> is
-satisfied where val is the corresponding value of the audio file
-(value of the year tag, bitrate in kbit/s, etc.).
-
-The year tag is special as its value is undefined if the audio file
-has no year tag or the content of the year tag is not a number. Such
-audio files never match. Another difference is the special treatment
-if the year tag is a two-digit number. In this case either 1900 or
-2000 is added to the tag value, depending on whether the number is
-greater than 2000 plus the current year.
-
+A mood consists of a unique name and a definition. The definition
+is an expression which describes which audio files are considered
+admissible. At any time at most one mood can be active, meaning
+that para_server will only stream files which are admissible for the
+active mood.
+
+The expression may refer to attributes and other metadata stored in
+the database. Expressions may be combined by means of logical and
+arithmetical operators in a natural way. Moreover, string matching
+based on regular expression or wildcard patterns is supported.
+
+The set of admissible files is determined by applying the expression
+to each audio file in turn. For a mood definition to be valid, its
+expression must evaluate to a number, a string or a boolean value
+("true" or "false"). For numbers, any value other than zero means the
+file is admissible. For strings, any non-empty string indicates an
+admissible file. For boolean values, true means admissible and false
+means not admissible. As a special case, the empty expression treats
+all files as admissible.
+
+<h3> Mood grammar </h3>
+
+Expressions are based on a context-free grammar which distinguishes
+between several types for syntactic units or groupings. The grammar
+defines a set of keywords which have a type and a corresponding
+semantic value, as shown in the following table.
+
+Keyword | Type | Semantic value
+:--------------------|--------:|:----------------------------------
+`path` | string | Full path of the current audio file
+`artist` | string | Content of the artist meta tag
+`title` | string | Content of the title meta tag
+`album` | string | Content of the album meta tag
+`comment` | string | Content of the somment meta tag
+`num_attributes_set` | integer | Number of attributes which are set
+`year` | integer | Content of the year meta tag [\*]
+`num_played` | integer | How many times the file has been streamed
+`image_id` | integer | The identifier of the (cover art) image
+`lyrics_id` | integer | The identifier of the lyrics blob
+`bitrate` | integer | The average bitrate
+`frequency` | integer | The output sample rate
+`channels` | integer | The number of channels
+`duration` | integer | The number of milliseconds
+`is_set("foo")` | boolean | True if attribute "foo" is set.
+
+[\*] For most audio formats, the year tag is stored as a string. It
+is converted to an integer by the mood parser. If the audio file
+has no year tag or the content of the year tag is not a number, the
+semantic value is zero. A special convention applies if the year tag
+is a one-digit or a two-digit number. In this case 1900 is added to
+the tag value.
+
+Expressions may be grouped using parentheses, logical and
+arithmetical operators or string matching operators. The following
+table lists the available operators.
+
+Token | Meaning
+:------|:-------
+`\|\|` | Logical Or
+`&&` | Logical And
+`!` | Logical Not
+`==` | Equal (can be applied to all types)
+`!=` | Not equal. Likewise
+`<` | Less than
+`<=` | Less or equal
+`>=` | Greater or equal
+`+` | Arithmetical minus
+`-` | Binary/unary minus
+`*` | Multiplication
+`/` | Division
+`=~` | Regular expression match
+`=\|` | Filename match
+
+Besides integers, strings and booleans there is an additional type
+which describes regular expression or wildcard patterns. Patterns
+are not just strings because they also include a list of flags which
+modify matching behaviour.
+
+Regular expression patterns are of the form `/pattern/[flags]`. That
+is, the pattern is delimited by slashes, and is followed by zero or
+more characters, each specifying a flag according to the following
+table
+
+Flag | POSIX name | Meaning
+:----|--------------:|--------
+`i` | `REG_ICASE` | Ignore case in match
+`n` | `REG_NEWLINE` | Treat newline as an ordinary character
+
+Note that only extended regular expression patterns are supported. See
+regex(3) for details.
+
+Wildcard patterns are similar, but the pattern must be delimited by
+`'|'` characters rather than slashes. For wildcard patterns different
+flags exist, as shown below.
+
+Flag | POSIX name | Meaning
+:----|-----------------------:|--------
+`n` | `FNM_NOESCAPE` | Treat backslash as an ordinary character
+`p` | `FNM_PATHNAME` | Match a slash only with a slash in pattern
+`P` | `FNM_PERIOD` | Leading period has to be matched exactly
+`l` | `FNM_LEADING_DIR` [\*] | Ignore "/\*" rest after successful matching
+`i` | `FNM_CASEFOLD` [\*] | Ignore case in match
+`e` | `FNM_EXTMATCH` [\*\*] | Enable extended pattern matching
+
+[\*] Not in POSIX, but both FreeBSD and NetBSD have it.
+
+[\*\*] GNU extension, silently ignored on non GNU systems.
+
+See fnmatch(3) for details.
+
+Mood definitions may contain arbitrary whitespace and comments.
+A comment is a word beginning with #. This word and all remaining
+characters of the line are ignored.
+
+<h3> Example moods </h3>
+
+* Files with no/invalid year tag: `year == 0`
+
+* Only oldies: `year != 0 && year < 1980`
+
+* Only 80's Rock or Metal: `(year >= 1980 && year < 1990) &&
+ (is_set("rock") || is_set("metal"))`
+
+* Files with incomplete tags: `artist == "" || title == "" || album =
+"" || comment == "" || year == 0`
+
+* Files with no attributes defined so far: `num_attributes_set == 0`
+
+* Only newly added files: `num_played == 0`
+
+* Only poor quality files: `bitrate < 96`
+
+* Cope with different spellings of Motörhead: `artist =~ /mot(ö|oe{0,1})rhead/i`
+
+* The same with extended wildcard patterns: `artist =| |mot+(o\|oe\|ö)rhead|ie`
<h3> Mood usage </h3>
para ls -a
-
-<h3> Example mood definition </h3>
-
-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
-
-
-
File renames and content changes
--------------------------------
- UDP. Recommended for multicast LAN streaming.
-See the Appendix on [network protocols](/#Network.protocols)
+See the Appendix on [network protocols](#Network.protocols)
for brief descriptions of the various protocols relevant for network
audio streaming with paraslash.
para_client si
-The sender command of para_server prints information about senders,
-like the various access control lists, and it allows to (de-)activate
-senders and to change the access permissions at runtime.
-
--> List all senders
-
- para_client sender
-
--> Obtain general help for the sender command:
-
- para_client help sender
-
--> Get help for a specific sender (contains further examples):
-
- s=http # or dccp or udp
- para_client sender $s help
-
--> Show status of the http sender
-
- para_client sender http status
-
By default para_server activates both the HTTP and th DCCP sender on
startup. This can be changed via command line options or para_server's
config file.
para_server -h
-All senders share the "on" and "off" commands, so senders may be
-activated and deactivated independently of each other.
-
--> Switch off the http sender:
-
- para_client sender http off
-
-> Receive a DCCP stream using CCID2 and write the output into a file:
host=foo.org; ccid=2; filename=bar
line parser, so arguments for the dccp receiver must be protected
from being interpreted by para_recv.
--> Start UDP multicast, using the default multicast address:
-
- para_client sender udp add 224.0.1.38
-
-> Receive FEC-encoded multicast stream and write the output into a file:
filename=foo
para_recv -r udp > $filename
--> Add an UDP unicast for a client to the target list of the UDP sender:
-
- t=client.foo.org
- para_client sender udp add $t
-
-> Receive this (FEC-encoded) unicast stream:
filename=foo
all. The wav filter is only useful with para_filter and in connection
with a decoder. It asks the decoder for the number of channels and the
sample rate of the stream and adds a Microsoft wave header containing
-this information at the beginning. This allows to write wav files
+this information at the beginning. This allows writing wav files
rather than raw PCM files (which do not contain any information about
the number of channels and the sample rate).
operating on uncompressed audio streams, since data buffers are simply
"pushed down" rather than copied.
-Examples
---------
-
--> Decode an mp3 file to wav format:
-
- para_filter -f mp3dec -f wav < file.mp3 > file.wav
-
--> Amplify a raw audio file by a factor of 1.5:
-
- para_filter -f amp --amp 32 < foo.raw > bar.raw
-
======
Output
======
also limited. For example only one application can open the device
at any time. The OSS writer is activated by default on BSD Systems.
-- *FILE*. The file writer allows to capture the audio stream and
-write the PCM data to a file on the file system rather than playing
+- *FILE*. The file writer allows capturing the audio stream and
+writing the PCM data to a file on the file system rather than playing
it through a sound device. It is supported on all platforms and is
always compiled in.
the configure file which is shipped in the tarballs but has to be
generated when compiling from git.
-- [discount](http://www.pell.portland.or.us/~orc/Code/discount). The
+- [discount](http://www.pell.portland.or.us/~orc/Code/discount/). The
HTML version of this manual and some of the paraslash web pages are
written in the Markdown markup language and are translated into html
with the converter of the *Discount* package.
The preferred coding style for paraslash coincides more or less
with the style of the Linux kernel. So rather than repeating what is
-written [there](http://www.kernel.org/doc/Documentation/process/coding-style.rst),
+written [there](https://www.kernel.org/doc/Documentation/process/coding-style.rst),
here are the most important points.
- Burn the GNU coding standards.
---------------------
- [paraslash](http://people.tuebingen.mpg.de/maan/paraslash/)
-- [xmms](http://xmms2.org/wiki/Main_Page)
+- [xmms](https://xmms2.org/wiki/Main_Page)
- [mpg123](http://www.mpg123.de/)
-- [gstreamer](http://gstreamer.freedesktop.org/)
+- [gstreamer](https://gstreamer.freedesktop.org/)
- [icecast](http://www.icecast.org/)
-- [Audio Compress](http://beesbuzz.biz/code/audiocompress.php)
+- [Audio Compress](https://beesbuzz.biz/code/audiocompress.php)
External documentation
----------------------
- [The mathematics of
-Raid6](http://kernel.org/pub/linux/kernel/people/hpa/raid6.pdf)
+Raid6](https://www.kernel.org/pub/linux/kernel/people/hpa/raid6.pdf)
by H. Peter Anvin
- [Effective Erasure Codes for reliable Computer Communication
projects / paraslash.git / blobdiff