#lang racket/base
(require net/uri-codec
net/url
racket/port
racket/tcp
(planet neil/mcfly))
(module+ test
(require (planet neil/overeasy)))
(doc (section "Introduction")
(para "This "
(racket vlc)
" package permit Racket programs to start and control a "
(hyperlink "http://www.videolan.org/vlc/" "VideoLAN VLC")
" media player, for playing video and audio.")
(para "VLC itself is a separate computer program, and must be installed
separately.")
(para "This package uses the "
(hyperlink
"http://www.videolan.org/doc/play-howto/en/ch04.html#id590986"
"VLC RC interface")
" over TCP. The Racket host OS process's address space is isolated
from potential memory-handling defects in the various native code libraries
involved in media playing.")
(para "For a simple example of using this package, imagine that you are
studying how to improve a corporate training video, and you have a theory that
the video would be more efficacious, were minimum-wage new hires not bored to
catatonia by the CEO's rambling 10-minute introduction. Fortunately, you have
human subjects available, since the new hires all use a Racket-based training
system that can be modified quickly to add scientific experiments, showing the
CEO's intro to some subjects but not to others. Unfortunately, you can't just
edit the training video to make an alternate version without the CEO's intro,
since the CEO is an aspiring Hollywood actor, who negotiated ``points'' on DVD
sales. Fortunately, you can use VLC and this Racket "
(tt "vlc")
" package, to launch the pertinent DVD chapter and seek past the
initial 10 minutes of Valium:")
(racketblock
(start-vlc "dvd:///dev/dvd#1:2")
(wait-for-vlc-active-playing)
(vlc-seek 594))
(para "In addition to highly contrived examples like that, this package is
being used as part of a Racket-based home theatre system being developed.")
(para "This package is currently developed using VLC 2.0.3, on Debian
GNU/Linux, and has been observed to also work on Mac OS X. MS Windows is not
currently supported (since, on MS Windows, VLC 2.0.3 does not support the RC
interface, and instead uses something called "
(tt "oldrc")
")."))
(doc (section "Processes & Connections")
(para "A connection to a VLC process is represented by the "
(racket vlc)
" object. This connection can be to a process that is started by
the "
(racket start-vlc)
" procedure, or an existing VLC process (possibly on a host
elsewhere on the network)."))
(define (%vlc:vlc-custom-write vlc port mode)
(fprintf port
"#<vlc :live? ~S :hostname ~S :port ~S ~A>"
(vlc-live? vlc)
(vlc-hostname vlc)
(vlc-port vlc)
(if (vlc-command-line vlc)
(format " :pid ~S :command-line ~S"
(subprocess-pid (vlc-subprocess vlc))
(vlc-command-line vlc))
"")))
(doc (defproc (vlc? (x any/c))
boolean?
(para "Predicate for whether or not "
(racket x)
" is a "
(racket vlc)
" object.")))
(provide vlc?)
(define-struct vlc
(sema
(live? #:mutable)
hostname
port
in
out
in-buf
prompt-key
command-line
subprocess)
#:methods gen:custom-write
((define write-proc %vlc:vlc-custom-write)))
(define-syntax %vlc:make-vlc-object/kw
(syntax-rules ()
((_ #:sema SEMA
#:live? LIVE?
#:hostname HOSTNAME
#:port PORT
#:in IN
#:out OUT
#:in-buf IN-BUF
#:prompt-key PROMPT-KEY
#:command-line COMMAND-LINE
#:subprocess SUBPROCESS)
(make-vlc SEMA
LIVE?
HOSTNAME
PORT
IN
OUT
IN-BUF
PROMPT-KEY
COMMAND-LINE
SUBPROCESS))))
(define %vlc:in-buf-size 8192)
(doc (defparam current-vlc
vlc
(or/c vlc? #f)
(para "Parameter for the "
(racket vlc)
" to use as the default for most procedures in this package
when the optional "
(racket #:vlc)
" argument is not supplied to the procedure.")))
(provide current-vlc)
(define current-vlc (make-parameter #f))
(define (%vlc:connect #:error-name error-name
#:port port
#:hostname hostname
#:connecting-timeout connecting-timeout
#:command-line command-line
#:subprocess subprocess)
(log-debug (format "~S: connecting to ~S:~S ..."
error-name
hostname
port))
(let*-values (((end-ms) (+ (current-inexact-milliseconds)
(* 1e3 connecting-timeout)))
((in out)
(let loop ((attempt 1))
(with-handlers* ((exn:fail:network?
(lambda (e)
(if (> (current-inexact-milliseconds)
end-ms)
(error error-name
"could not connect to VLC RC at ~S:~S within timeout ~S seconds after ~S attempts: ~S"
hostname
port
connecting-timeout
attempt
(exn-message e))
(begin (log-debug (format "~S: connect attempt ~S failed; reattempting..."
error-name
attempt))
(sleep 0.1)
(loop (+ 1 attempt)))))))
(tcp-connect/enable-break hostname port))))
((in-buf) (make-bytes %vlc:in-buf-size))
((prompt-key) (string->bytes/latin-1 (number->string (random 4294967087))))
((prompt-bytes) (bytes-append #"RACKET-VLC-RC-PROMPT-"
prompt-key
#"> "))
((vlc) (%vlc:make-vlc-object/kw
#:sema (make-semaphore 1)
#:live? #t
#:hostname hostname
#:port port
#:in in
#:out out
#:in-buf in-buf
#:prompt-key prompt-key
#:command-line command-line
#:subprocess subprocess)))
(log-debug (format "~S: connected"
error-name))
(let loop-consume-any-input ((seen-any? #f)
(have-prompt? #f))
(log-debug (format "~S: syncing waiting for input..."
error-name))
(let ((evt (sync/timeout/enable-break (if seen-any?
1
(max 1
(- end-ms
(current-inexact-milliseconds))))
in)))
(if evt
(begin (log-debug (format "~S: syncing on ~S"
error-name
evt))
(let ((count-or-eof (read-bytes-avail!/enable-break in-buf in)))
(if (eof-object? count-or-eof)
(error error-name
"got EOF while syncing")
(begin (log-debug (format "~S: syncing skipped ~S"
error-name
(subbytes in-buf 0 count-or-eof)))
(if (and (>= count-or-eof 1)
(regexp-match? #rx#"> ?$" in-buf
(max 0 (- count-or-eof 2))
count-or-eof))
(loop-consume-any-input #t #t)
(loop-consume-any-input #t #f))))))
(begin
(if seen-any?
(if have-prompt?
(log-debug (format "~S: syncing timeout without any more input"
error-name))
(log-warning (format "~S: syncing saw some input but not a prompt"
error-name)))
(log-warning (format "~S: syncing did not see any input"
error-name)))
(%vlc:command-without-output error-name
vlc
(bytes-append #"set prompt \""
prompt-bytes
#"\"\n"))
vlc))))))
(doc (defproc (connect-to-vlc
(#:port port (and/c exact-nonnegative-integer?
(integer-in 1 65535)))
(#:hostname hostname string? "localhost")
(#:connecting-timeout connecting-timeout (and/c real? (not/c negative?)) 5.0)
(#:set-current-vlc? set-current-vlc? boolean? #t))
vlc?
(para "Connect to the RC interface on an existing process, at TCP "
(racket hostname)
" and "
(racket port)
", and return a "
(racket vlc)
" object. If "
(racket set-current-vlc?)
" is true, which is the default, then the "
(racket current-vlc)
" parameter is also set.")
(para (racket connecting-timeout)
" is a guideline of the maximum number of seconds total that
should be spend attempting to get a TCP connection to the VLC process and then
exchange certain initial protocol. It is not a hard limit, however. Note that
multiple attempts at the TCP connection may be tried within that limit, for
situations such as waiting for a VLC process to start up.")))
(provide connect-to-vlc)
(define (connect-to-vlc #:port port
#:hostname (hostname "localhost")
#:connecting-timeout (connecting-timeout 0.5)
#:set-current-vlc? (set-current-vlc? #t))
(let ((vlc (%vlc:connect #:error-name 'connect-to-vlc
#:port port
#:hostname hostname
#:connecting-timeout connecting-timeout
#:command-line #f
#:subprocess #f)))
(and set-current-vlc? (current-vlc vlc))
vlc))
(define (%vlc:get-unused-tcp-port-number (hostname "localhost"))
(let ((listener (tcp-listen 0 1 #f hostname)))
(let-values (((local-hostname local-port remote-hostname remote-port)
(tcp-addresses listener #t)))
(tcp-close listener)
local-port)))
(define (%vlc:do-process-logger pid logger level stdout-in stderr-in)
(let* ((buf-size 256)
(buf (make-bytes buf-size)))
(if logger
(log-debug (format "vlc: logging process ~S stdout and stderr to ~S"
pid
logger))
(log-debug (format "vlc: discarding process ~S stdout and stderr"
pid)))
(let loop ((evts (list stdout-in stderr-in)))
(if (null? evts)
(log-debug (format "vlc: process ~S stdout and stderr done"
pid))
(let ((evt (apply sync/enable-break evts)))
(let ((port-name (cond ((eq? evt stdout-in) 'stdout)
((eq? evt stderr-in) 'stderr)
(else (error '%vlc:do-process-logger
"got unknown event ~S from PID ~S"
evt
pid)))))
(let ((num (read-bytes-avail!/enable-break buf evt 0 buf-size)))
(cond ((number? num)
(and logger
(parameterize ((current-logger logger))
(log-message logger
level
(format "vlc ~S ~S: ~S"
pid
port-name
(subbytes buf 0 num))
#f)))
(loop evts))
((eof-object? num)
(log-debug (format "vlc: process ~S ~S EOF"
pid
port-name))
(loop (remq evt evts)))
((procedure? num)
(log-warning (format "vlc: process ~S ~S special object ~S"
pid
port-name
num))
(loop evts))
(else
(error '%vlc:do-process-logger
"process ~S ~S unknown object ~S"
pid
port-name
num))))))))))
(doc (defproc (start-vlc
(#:port port (or/c #f
(and/c exact-nonnegative-integer?
(integer-in 1 65535)))
#f)
(#:hostname hostname string? "localhost")
(#:connecting-timeout connecting-timeout (or/c #f (and/c real? (not/c negative?)))
60.0)
(#:logger logger (or/c #f logger?) (current-logger))
(#:logger-level logger-level (or/c 'fatal 'error 'warning 'info 'debug) 'info)
(#:set-current-vlc? set-current-vlc? boolean? #t)
(#:command command (or/c #f path-string?) #f)
( extra-args (listof (or/c string? path?)) '())
...)
vlc?
(para "Start a VLC process on the same machine on which this Racket
program is running, with RC enabled, and connect to it. A "
(racket vlc)
" object is returned. If "
(racket set-current-vlc?)
" is true, which is the default, then the "
(racket current-vlc)
" parameter is also set.")
(para (racket command)
" is a string or "
(racket path)
" object for the complete path to the VLC executable; or, if the default of "
(racket #f)
", then this package attempts to find the VLC executable.")
(para "This package supplies some command-line arguments to VLC, to set
up the RC interface. Additional command-line arguments can be supplied as
strings and/or "
(racket path)
" objects to the "
(racket extra-args)
" argument of this procedure.")
(racketblock
(start-vlc "--snapshot-path=/home/me/film-class/review-screenshots"
"dvd:///dev/dvd"))
(para "If "
(racket logger)
" is "
(racket #f)
", then "
(tt "stdout")
" and "
(tt "stderr")
" output is consumed and ignored. Otherwise, such output is
redirected to the logger, with the log level specified by "
(racket logger-level)
".")
(para "If "
(racket port)
" is "
(racket #f)
", which is the default, then this package attempts to select a
TCP port in the ephemeral range for VLC to use for RC; otherwise, "
(racket port)
" is the port number to use.")
(para (racket hostname)
" is the string hostname (or the IP address as a string) on which
VLC should listen on the TCP port for RC. By default, this is "
(racket "localhost")
", which is what you normally want with "
(racket start-vlc)
" rather than "
(racket connect-to-vlc)
". In the unlikely event that you wish for the RC port of this
VLC process to also be accessible from other hosts, you may supply the hostname
or IP address for a non-"
(tt "localhost")
" interface.")
(para (racket connecting-timeout)
" is as documented for "
(racket connect-to-vlc)
".")
(para "The VLC process is started under the current custodian. If you are calling "
(racket start-vlc)
" from a short-lived thread with its own custodian that you
shutdown as the thread exits, such as for an HTTP request that triggers
starting of VLC, you might want to do something like:")
(racketblock
(parameterize ((current-custodian #,(italic "<long-lived-custodian>")))
(start-vlc)))))
(provide start-vlc)
(define (start-vlc
#:hostname (hostname "localhost")
#:port (port 0)
#:connecting-timeout (connecting-timeout 60.0)
#:logger (logger (current-logger))
#:logger-level (logger-level 'info)
#:set-current-vlc? (set-current-vlc? #t)
#:command (command #f)
. extra-args)
(let*-values
(((port)
(if (zero? port)
(%vlc:get-unused-tcp-port-number hostname)
port))
((command)
(cond ((not command)
(cond ((find-executable-path "vlc") => path->string)
((find-executable-path "VLC") => path->string)
(else (let loop ((lst '("/usr/local/bin/vlc"
"/Applications/VLC.app/Contents/MacOS/VLC"
"\\Program Files\\VideoLAN\\VLC\\vlc.exe"
"C:\\Program Files\\VideoLAN\\VLC\\vlc.exe")))
(if (null? lst)
(error 'start-vlc
"#:command was #f and could not find VLC executable")
(let ((str (car lst)))
(if (file-exists? str)
(begin (log-debug (format "start-vlc: VLC was not in executable search path, but found it in ~S"
str))
str)
(loop (cdr lst)))))))))
((string? command) command)
((path? command) (path->string command))
(else (raise-type-error 'start-vlc
"(or/c #f string? path?)"
command))))
((args)
`("-I"
"rc"
,(string-append "--rc-host="
hostname
":"
(number->string port))
,@(map (lambda (arg)
(cond ((path? arg) (path->string arg))
(else arg)))
extra-args)))
((subproc stdout-in stdin-out stderr-in)
(parameterize ((subprocess-group-enabled #t)
(current-subprocess-custodian-mode 'kill))
(apply subprocess
#f #f #f (cons command args)))))
(with-handlers* ((exn:fail? (lambda (e)
(log-debug "start-vlc: attempting to kill subprocess due to exception")
(with-handlers* ((exn:fail? (lambda (e)
(log-debug (format "start-vlc: subprocess kill failed: ~S"
(exn-message e))))))
(subprocess-kill subproc #t)
(raise e)))))
(log-debug (format "start-vlc: process PID is ~S"
(subprocess-pid subproc)))
(let ((vlc (%vlc:connect #:error-name 'start-vlc
#:port port
#:hostname hostname
#:connecting-timeout connecting-timeout
#:command-line (cons command args)
#:subprocess subproc)))
(thread (lambda ()
(%vlc:do-process-logger (subprocess-pid subproc)
logger
logger-level
stdout-in
stderr-in)))
(and set-current-vlc? (current-vlc vlc))
vlc))))
(doc (section "URLs")
(para "URLs may be provided to VLC commands in any of a few different
formats. See documentation for "
(racket vlc-url?)
"."))
(define %vlc:fully-url-escape-byte-string
(let ((hex-ascii-bytes-vector
'#(48 49 50 51 52 53 54 55 56 57 97 98 99 100 101 102)))
(lambda (bstr)
(let* ((bstr-len (bytes-length bstr))
(result (make-bytes (* 3 bstr-len) 37)))
(let loop ((i 0))
(if (= i bstr-len)
result
(let ((byte (bytes-ref bstr i))
(start (+ 1 (* 3 i))))
(bytes-set! result
start
(vector-ref hex-ascii-bytes-vector
(quotient byte 16)))
(bytes-set! result
(+ 1 start)
(vector-ref hex-ascii-bytes-vector
(remainder byte 16)))
(loop (+ 1 i)))))))))
(define %vlc:char->fully-url-escaped-utf-8-byte-string
(let* ((compute (lambda (chr)
(%vlc:fully-url-escape-byte-string
(string->bytes/utf-8 (string chr)))))
(cache-size 256)
(cache (for/vector ((i (in-range 0 256)))
(compute (integer->char i)))))
(lambda (chr)
(let ((num (char->integer chr)))
(if (< num cache-size)
(vector-ref cache num)
(compute chr))))))
(define (%vlc:path-string->file-url-escaped-bytes str)
(let ((str-len (string-length str)))
(let loop ((start 0)
(reverse-result '()))
(cond ((= start str-len)
(if (null? reverse-result)
(string->bytes/latin-1 str)
(apply string-append
(reverse reverse-result))))
((regexp-match-positions #rx"[^-_./0-9A-Za-z]" str start)
=> (lambda (m)
(let ((char-pos (caar m))
(next-start (cdar m)))
(loop next-start
(cons (%vlc:char->fully-url-escaped-utf-8-byte-string (string-ref str char-pos))
(if (= char-pos start)
reverse-result
(cons (string->bytes/latin-1 (substring str start char-pos))
reverse-result)))))))
((null? reverse-result) (string->bytes/latin-1 str))
(else (apply bytes-append
(reverse (cons (string->bytes/latin-1 (substring str start str-len))
reverse-result))))))))
(define (%vlc:string->vlc-rc-url-bytes str)
(if (regexp-match? #rx"^[a-z][-a-z0-9]+:" str)
(string->bytes/latin-1 str)
(%vlc:path-string->vlc-rc-url-bytes str)))
(define (%vlc:path-string->vlc-rc-url-bytes path-str)
(let ((file-url-escaped-bytes (%vlc:path-string->file-url-escaped-bytes path-str)))
(if (regexp-match? #rx#"^/" file-url-escaped-bytes)
(bytes-append #"file://" file-url-escaped-bytes)
(bytes-append #"file:" file-url-escaped-bytes))))
(doc (defproc (vlc-url? (x any/c))
boolean?
(para "Predicate for whether or not "
(racket x)
" can (likely) be used as a URL argument to procedures like "
(racket vlc-add)
" and "
(racket vlc-enqueue)
". Specifically, URLs can be represented as one of the following:")
(itemlist
(item "String starting with a URL scheme, such as "
(racket "http://example.com/foo.mp4")
". Note that this string must contain a "
(tt "%")
"-escaped URL, with no spaces or other problematic characters.")
(item (racket url)
" object, such as is produced by "
(racket (string->url "http://example.com/bar/foo.mp4"))
".")
(item "String "
(italic "not")
" starting with a URL scheme, such as "
(racket "/home/billybob/tractors.mp4")
", which is a file path.")
(item (racket path)
" object, such as is produced by "
(racket (string->path "/home/scotty/sheep.wav"))
".")
(item "Byte string of a complete URL in UTF-8 encoding, including "
(tt "%")
"-escaping. This is passed verbatim in the RC protocol."))
(para "Note that URLs provided to commands are processed by the VLC
program, which might be on a different computer than the Racket program that is
sending commands. URLs that may be accessed from one computer can't
necessarily be accessed by another.")))
(provide vlc-url?)
(define (vlc-url? x)
(or (string? x) (path? x) (url? x) (bytes? x)))
(doc (defproc (to-vlc-rc-url-bytes (x (or/c string? path? url? bytes?)))
bytes?
(para "Accepts a VLC URL as described in the documentation for "
(racket vlc-url?)
" and yields a byte string representation. Note that, if "
(racket x)
" is a byte string, then it is returned verbatim. This procedure
will not be called directly by most programs using this package.")))
(provide to-vlc-rc-url-bytes)
(define (to-vlc-rc-url-bytes x)
(cond ((string? x) (%vlc:string->vlc-rc-url-bytes x))
((path? x) (%vlc:path-string->vlc-rc-url-bytes (path->string x)))
((url? x) (string->bytes/latin-1
(parameterize ((current-alist-separator-mode 'amp))
(url->string x))))
((bytes? x) x)
(else (raise-type-error 'to-vlc-rc-url-bytes
"(or/c string? bytes? path? url)"
x))))
(module+ test
(test (to-vlc-rc-url-bytes "foo.mp4") #"file:foo.mp4")
(test (to-vlc-rc-url-bytes "foo bar.mp4") #"file:foo%20bar.mp4")
(test (to-vlc-rc-url-bytes "/foo.mp4") #"file:///foo.mp4")
(test (to-vlc-rc-url-bytes "/foo bar.mp4") #"file:///foo%20bar.mp4")
(test (to-vlc-rc-url-bytes "http://foo/bar.mp4") #"http://foo/bar.mp4")
(test (to-vlc-rc-url-bytes #"http://foo/bar.mp4") #"http://foo/bar.mp4")
(test (to-vlc-rc-url-bytes (string->url "http://foo/bar.mp4")) #"http://foo/bar.mp4"))
(doc (section "Commands")
(para "This section lists the various command procedures. Generally, each
procedure corresponds to a VLC RC command. For example, "
(racket vlc-add)
" corresponds to the RC "
(tt "add")
" command. For the most part, these procedures are defined to ``do
whatever the RC command does.'' The RC command itself might not be
well-documented. So, for example, if, in the version of VLC being used, the "
(tt "add")
" command results in the the specified URL both being prepended to
the playlist and being played, then that's what the "
(racket vlc-add)
" command will do.")
(para "Note that some of these commands have asynchronous effects, due to
the design of VLC or of the VLC RC protocol. For example, the "
(racket vlc-play)
" procedure can return before VLC is actually playing the media."))
(define (%vlc:format-float-rc-bytes n)
(string->bytes/utf-8 (number->string (real->double-flonum n))))
(define (%vlc:format-fixnum-rc-bytes n)
(string->bytes/utf-8 (number->string n)))
(define (%vlc:parse-rc-bytes-to-number bstr)
(cond ((regexp-match #rx"^[ \t\r\n]*([0-9]+(?:\\.[0-9]+)?)[ \t\r\n]*$"
(bytes->string/utf-8 bstr))
=> (lambda (m)
(string->number (cadr m))))
(else (error '%vlc:parse-rc-bytes-to-number
"RC bytes ~S is not a number"
bstr))))
(define (%vlc:parse-rc-bytes-to-boolean bstr)
(cond ((regexp-match #rx"^[ \t\r\n]*([01])[ \t\r\n]*$"
(bytes->string/utf-8 bstr))
=> (lambda (m)
(if (equal? "1" (cadr m))
#t
#f)))
(else (error '%vlc:parse-rc-bytes-to-boolean
"RC bytes ~S is not a boolean"
bstr))))
(define (%vlc:parse-vlc-bar-output bstr)
(let ((in (open-input-bytes bstr)))
(let loop-section ()
(cond ((eof-object? (peek-char in))
'())
((regexp-try-match #rx"^\\+----\\[ ([^]]+) ]\r?\n" in)
=> (lambda (m)
(let ((section-name (bytes->string/utf-8 (list-ref m 1))))
(if (eof-object? (peek-char in))
'()
(cons (cons section-name
(let loop-row ()
(cond ((regexp-try-match #rx"^\\| +([^\r\n]*)\r?\n" in)
=> (lambda (m)
(cons (bytes->string/utf-8 (list-ref m 1))
(loop-row))))
((eqv? #\+ (peek-char in))
'())
(else (error '%vlc:parse-vlc-bar-output
"could not match row in ~S"
bstr)))))
(loop-section))))))
(else (error '%vlc:parse-vlc-bar-output
"could not match section start in ~S"
bstr))))))
(module+ test
(test (%vlc:parse-vlc-bar-output
(bytes-append
#"+----[ spu-es ]\r\n"
#"| -1 - Disable *\r\n"
#"| 14 - Track 1 - [Fran\303\247ais]\r\n"
#"| 15 - Track 2 - [Espa\303\261ol]\r\n"
#"| 17 - Closed captions 1\r\n"
#"| 18 - Closed captions 2\r\n"
#"| 19 - Closed captions 3\r\n"
#"| 20 - Closed captions 4\r\n"
#"+----[ end of spu-es ]\r\n"))
'(("spu-es"
"-1 - Disable *"
"14 - Track 1 - [Fran\u00e7ais]"
"15 - Track 2 - [Espa\u00f1ol]"
"17 - Closed captions 1"
"18 - Closed captions 2"
"19 - Closed captions 3"
"20 - Closed captions 4"))))
(define (%vlc:command-with-output error-name
rc
command-bytes-including-newline)
(log-debug (format "~S: semaphore wait. command is ~S"
error-name
command-bytes-including-newline))
(call-with-semaphore/enable-break
(vlc-sema rc)
(lambda ()
(log-debug (format "~S: writing..."
error-name))
(write-bytes command-bytes-including-newline
(vlc-out rc))
(flush-output (vlc-out rc))
(log-debug (format "~S: waiting for response"
error-name))
(let* ((result-ob (open-output-bytes)))
(cond ((regexp-match #rx#"RACKET-VLC-RC-PROMPT-([0-9]+)> "
(vlc-in rc)
0
#f
result-ob)
=> (lambda (m)
(let ((expected-key (vlc-prompt-key rc))
(actual-key (cadr m)))
(if (equal? expected-key actual-key)
(let ((bstr (get-output-bytes result-ob)))
(log-debug (format "~S: received response ~S"
error-name
bstr))
bstr)
(error error-name
"received prompt key ~S does not match expected ~S. multiple remotes for one vlc?"
actual-key
expected-key)))))
(else (error error-name
"no response to command ~S"
command-bytes-including-newline)))))))
(define (%vlc:command-with-string-output error-name
rc
command-bytes-including-newline)
(bytes->string/utf-8
(regexp-replace #rx#"\r?\n$"
(%vlc:command-with-output error-name
rc
command-bytes-including-newline)
#"")))
(define (%vlc:command-with-number-output error-name
rc
command-bytes-including-newline)
(let ((result (%vlc:parse-rc-bytes-to-number
(%vlc:command-with-output error-name
rc
command-bytes-including-newline))))
(log-debug (format "~S: number response is: ~S"
error-name
result))
result))
(define (%vlc:command-with-boolean-output error-name
rc
command-bytes-including-newline)
(let ((result (%vlc:parse-rc-bytes-to-boolean
(%vlc:command-with-output error-name
rc
command-bytes-including-newline))))
(log-debug (format "~S: boolean response is: ~S"
error-name
result))
result))
(define (%vlc:command-with-ignored-output error-name
rc
command-bytes-including-newline)
(%vlc:command-with-output error-name
rc
command-bytes-including-newline)
(void))
(define (%vlc:command-without-output error-name
rc
command-bytes-including-newline)
(let ((result-bytes (%vlc:command-with-output error-name
rc
command-bytes-including-newline)))
(if (equal? #"" result-bytes)
(void)
(error error-name
"did not expect command ~S to return output, but received ~S"
command-bytes-including-newline
result-bytes))))
(doc (subsection "Playlist"))
(doc (defproc (vlc-clear (#:vlc vlc vlc? (current-vlc)))
void?
(para "Clear all items from the playlist.")))
(provide vlc-clear)
(define (vlc-clear #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-clear
rc
#"clear\n"))
(doc (defproc (vlc-add (thing vlc-url?) (#:vlc vlc vlc? (current-vlc)))
void?
(para "Adds the URL "
(racket thing)
" to the playlist. This command seems to also cause VLC to start
playing the item.")))
(provide vlc-add)
(define (vlc-add thing #:vlc (rc (current-vlc)))
(%vlc:command-without-output
'vlc-add
rc
(bytes-append #"add "
(to-vlc-rc-url-bytes thing)
#"\n")))
(doc (defproc (vlc-enqueue (thing vlc-url?) (#:vlc vlc vlc? (current-vlc)))
void?
(para "Enqueues the URL "
(racket thing)
" in the playlist.")))
(provide vlc-enqueue)
(define (vlc-enqueue thing #:vlc (vlc (current-vlc)))
(%vlc:command-without-output
'vlc-enqueue
vlc
(bytes-append #"enqueue "
(to-vlc-rc-url-bytes thing)
#"\n")))
(doc (defproc (vlc-next (#:vlc vlc vlc? (current-vlc)))
void?
(para "Start playing the next item in the playlist.")))
(provide vlc-next)
(define (vlc-next #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-next
rc
#"next\n"))
(doc (defproc (vlc-prev (#:vlc vlc vlc? (current-vlc)))
void?
(para "Start playing the previous item in the playlist.")))
(provide vlc-prev)
(define (vlc-prev #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-prev
rc
#"prev\n"))
(doc (subsection "Repeat / Loop / Random"))
(doc (defproc (vlc-repeat (on? boolean)
(#:vlc vlc vlc? (current-vlc)))
void?
(para "Set whether VLC should repeat playing the current stream continuously.")))
(provide vlc-repeat)
(define (vlc-repeat on? #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-repeat
rc
(if on?
#"repeat on\r\n"
#"repeat off\r\n")))
(doc (defproc (vlc-loop (on? boolean)
(#:vlc vlc vlc? (current-vlc)))
void?
(para "Set whether VLC should repeat playing the playlist continuously.")))
(provide vlc-loop)
(define (vlc-loop on? #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-loop
rc
(if on?
#"loop on\r\n"
#"loop off\r\n")))
(doc (defproc (vlc-random (on? boolean)
(#:vlc vlc vlc? (current-vlc)))
void?
(para "Set whether VLC should select streams from the playlist randomly,
rather than in order.")))
(provide vlc-random)
(define (vlc-random on? #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-random
rc
(if on?
#"random on\r\n"
#"random off\r\n")))
(doc (subsection "Title and Chapter"))
(doc (defproc (vlc-title-n (#:vlc vlc vlc? (current-vlc)))
void?
(para "Switch to the next title of the current stream.")))
(provide vlc-title-n)
(define (vlc-title-n #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-title-n
rc
#"title_n\n"))
(doc (defproc (vlc-title-p (#:vlc vlc vlc? (current-vlc)))
void?
(para "Switch to the previous title of the current stream.")))
(provide vlc-title-p)
(define (vlc-title-p #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-title-p
rc
#"title_p\n"))
(doc (defproc (vlc-chapter-n (#:vlc vlc vlc? (current-vlc)))
void?
(para "Switch to the next chapter of the current stream.")))
(provide vlc-chapter-n)
(define (vlc-chapter-n #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-chapter-n
rc
#"chapter_n\n"))
(doc (defproc (vlc-chapter-p (#:vlc vlc vlc? (current-vlc)))
void?
(para "Switch to the previous chapter of the current stream.")))
(provide vlc-chapter-p)
(define (vlc-chapter-p #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-chapter-p
rc
#"chapter_p\n"))
(doc (subsection "Play, Pause, and Stop"))
(doc (defproc (vlc-play (#:vlc vlc vlc? (current-vlc)))
void?
(para "Play the next stream, if not already playing one.")))
(provide vlc-play)
(define (vlc-play #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-play
rc
#"play\n"))
(doc (defproc (vlc-pause (#:vlc vlc vlc? (current-vlc)))
void?
(para "Toggle the playing pause state.")))
(provide vlc-pause)
(define (vlc-pause #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-pause
rc
#"pause\n"))
(doc (defproc (vlc-stop (#:vlc vlc vlc? (current-vlc)))
void?
(para "Stop playing the current stream, if playing or paused.")))
(provide vlc-stop)
(define (vlc-stop #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-stop
rc
#"stop\n"))
(doc (defproc (vlc-is-playing (#:vlc vlc vlc? (current-vlc)))
number?
(para "Yields a boolean value for whether or not a stream is
playing.")))
(provide vlc-is-playing)
(define (vlc-is-playing #:vlc (rc (current-vlc)))
(%vlc:command-with-boolean-output 'vlc-is-playing
rc
#"is_playing\r\n"))
(doc (subsection "Rate"))
(doc (defproc (vlc-fastforward (#:vlc vlc vlc? (current-vlc)))
void?
(para "Set rate of playing to maximum.")))
(provide vlc-fastforward)
(define (vlc-fastforward #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-fastforward
rc
#"fastforward\n"))
(doc (defproc (vlc-rewind (#:vlc vlc vlc? (current-vlc)))
void?
(para "Set rate of playing to maximum reverse.")))
(provide vlc-rewind)
(define (vlc-rewind #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-rewind
rc
#"rewind\n"))
(doc (defproc (vlc-faster (#:vlc vlc vlc? (current-vlc)))
void?
(para "Increase the rate of playing of the current stream.")))
(provide vlc-faster)
(define (vlc-faster #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-faster
rc
#"faster\n"))
(doc (defproc (vlc-slower (#:vlc vlc vlc? (current-vlc)))
void?
(para "Lower the rate of playing of the current stream.")))
(provide vlc-slower)
(define (vlc-slower #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-slower
rc
#"slower\n"))
(doc (defproc (vlc-normal (#:vlc vlc vlc? (current-vlc)))
void?
(para "Play the current stream, and at normal speed.")))
(provide vlc-normal)
(define (vlc-normal #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-normal
rc
#"normal\n"))
(doc (defproc (vlc-frame (#:vlc vlc vlc? (current-vlc)))
void?
(para "Set current stream playing to frame-by-frame, or advance one
frame.")))
(provide vlc-frame)
(define (vlc-frame #:vlc (rc (current-vlc)))
(%vlc:command-without-output 'vlc-frame
rc
#"frame\n"))
(doc (defproc (vlc-rate (rate real?)
(#:vlc vlc vlc? (current-vlc)))
void?
(para "Set playing rate to "
(racket rate)
".")))
(provide vlc-rate)
(define (vlc-rate seconds #:vlc (rc (current-vlc)))
(if (real? seconds)
(%vlc:command-without-output 'vlc-rate
rc
(bytes-append #"rate "
(%vlc:format-float-rc-bytes seconds)
#"\r\n"))
(raise-type-error 'vlc-rate
"real?"
seconds)))
(doc (subsection "Absolute Position"))
(doc (defproc (vlc-get-time (#:vlc vlc vlc? (current-vlc)))
number?
(para "Get the time position of the current stream, in seconds.")))
(provide vlc-get-time)
(define (vlc-get-time #:vlc (rc (current-vlc)))
(%vlc:command-with-number-output 'vlc-get-time
rc
#"get_time\r\n"))
(doc (defproc (vlc-get-length (#:vlc vlc vlc? (current-vlc)))
number?
(para "Get the length of the current stream, in seconds.")))
(provide vlc-get-length)
(define (vlc-get-length #:vlc (rc (current-vlc)))
(%vlc:command-with-number-output 'vlc-get-length
rc
#"get_length\r\n"))
(doc (defproc (vlc-seek (seconds exact-nonnegative-integer?)
(#:vlc vlc vlc? (current-vlc)))
void?
(para "Seek playing to position "
(racket seconds)
".")))
(provide vlc-seek)
(define (vlc-seek seconds #:vlc (rc (current-vlc)))
(if (exact-nonnegative-integer? seconds)
(%vlc:command-without-output 'vlc-seek
rc
(bytes-append #"seek "
(%vlc:format-fixnum-rc-bytes seconds)
#"\r\n"))
(raise-type-error 'vlc-seek
"exact-nonnegative-integer?"
seconds)))
(doc (subsection "Audio, Video, and Subtitle Tracks"))
(define (%vlc:parse-vlc-track-output bstr)
(let ((sections (%vlc:parse-vlc-bar-output bstr)))
(let loop-sections ((sections sections)
(selected #f)
(reverse-out-sections '()))
(if (null? sections)
(values selected (reverse reverse-out-sections))
(let* ((section (car sections))
(section-name (car section)))
(let loop-rows ((rows (cdr section))
(selected selected)
(reverse-out-rows '()))
(if (null? rows)
(loop-sections (cdr sections)
selected
(cons (cons section-name
(reverse reverse-out-rows))
reverse-out-sections))
(let ((row (car rows)))
(cond ((regexp-match #rx"^(-?[0-9]+) +- +(.*)$" row)
=> (lambda (m)
(let ((id (string->number (list-ref m 1)))
(row-name (list-ref m 2)))
(cond ((regexp-match #rx"^(.*[^ ])( +\\*)$" row-name)
=> (lambda (m)
(loop-rows (cdr rows)
id
(cons (cons (list-ref m 1)
id)
reverse-out-rows))))
(else (loop-rows (cdr rows)
selected
(cons (cons row-name id)
reverse-out-rows)))))))
(else (error '%vlc:parse-vlc-track-output
"could not match row ~S in ~S"
row
bstr)))))))))))
(module+ test
(test (%vlc:parse-vlc-track-output
(bytes-append
#"+----[ spu-es ]\r\n"
#"| -1 - Disable *\r\n"
#"| 14 - Track 1 - [Fran\303\247ais]\r\n"
#"| 15 - Track 2 - [Espa\303\261ol]\r\n"
#"| 17 - Closed captions 1\r\n"
#"| 18 - Closed captions 2\r\n"
#"| 19 - Closed captions 3\r\n"
#"| 20 - Closed captions 4\r\n"
#"+----[ end of spu-es ]\r\n"))
(values -1
'(("spu-es"
. (("Disable" . -1)
("Track 1 - [Fran\u00e7ais]" . 14)
("Track 2 - [Espa\u00f1ol]" . 15)
("Closed captions 1" . 17)
("Closed captions 2" . 18)
("Closed captions 3" . 19)
("Closed captions 4" . 20)))))))
(define-syntax %vlc:track-lambda
(syntax-rules ()
((_ #:error-name ERROR-NAME
#:command-bytes COMMAND-BYTES)
(lambda ((num (void))
#:vlc (vlc (current-vlc)))
(if (void? num)
(%vlc:parse-vlc-track-output
(%vlc:command-with-output ERROR-NAME
vlc
#"strack\n"))
(if (exact-integer? num)
(%vlc:command-without-output ERROR-NAME
vlc
(bytes-append COMMAND-BYTES
#" "
(%vlc:format-fixnum-rc-bytes num)
#"\r\n"))
(raise-type-error ERROR-NAME
"exact-integer?"
num)))))))
(doc (defproc* (((vlc-atrack (#:vlc vlc vlc? (current-vlc)))
(values integer?
(listof (cons/c string? (listof (cons/c string? integer?))))))
((vlc-atrack (num integer?) (#:vlc vlc vlc? (current-vlc)))
void?))
(para "If "
(racket num)
" is "
(italic "not")
" provided, yields information about current and available audio
tracks for the current stream.")
(para "If "
(racket num)
" "
(italic "is")
" provided, switches the audio to that track.")))
(provide vlc-atrack)
(define vlc-atrack
(%vlc:track-lambda #:error-name 'vlc-atrack
#:command-bytes #"atrack"))
(doc (defproc* (((vlc-vtrack (#:vlc vlc vlc? (current-vlc)))
(values integer?
(listof (cons/c string? (listof (cons/c string? integer?))))))
((vlc-vtrack (num integer?) (#:vlc vlc vlc? (current-vlc)))
void?))
(para "If "
(racket num)
" is "
(italic "not")
" provided, yields information about current and available video
tracks for the current stream.")
(para "If "
(racket num)
" "
(italic "is")
" provided, switches the audio to that track.")))
(provide vlc-vtrack)
(define vlc-vtrack
(%vlc:track-lambda #:error-name 'vlc-vtrack
#:command-bytes #"vtrack"))
(doc (defproc* (((vlc-strack (#:vlc vlc vlc? (current-vlc)))
(values integer?
(listof (cons/c string? (listof (cons/c string? integer?))))))
((vlc-strack (num integer?) (#:vlc vlc vlc? (current-vlc)))
void?))
(para "If "
(racket num)
" is "
(italic "not")
" provided, yields information about current and available
subtitles and captions tracks for the current stream. For example, for one
DVD: ")
(racketinput
(vlc-strack))
(racketresultblock
-1
'(("spu-es"
("Disable" . -1)
("Track 1 - [Fran\u00e7ais]" . 14)
("Track 2 - [Espa\u00f1ol]" . 15)
("Closed captions 1" . 17)
("Closed captions 2" . 18)
("Closed captions 3" . 19)
("Closed captions 4" . 20))))
(para "If "
(racket num)
" "
(italic "is")
" provided, switches the subtitles/captions to that track.")))
(provide vlc-strack)
(define vlc-strack
(%vlc:track-lambda #:error-name 'vlc-strack
#:command-bytes #"strack"))
(doc (subsection "Audio Options"))
(doc (subsection "Video Options"))
(doc (defproc (vlc-fullscreen (on? boolean?)
(#:vlc vlc vlc? (current-vlc)))
void?
(para "Set whether VLC is in fullscreen mode.")))
(provide vlc-fullscreen)
(define (vlc-fullscreen on? #:vlc (vlc (current-vlc)))
(%vlc:command-without-output 'vlc-fullscreen
vlc
(if on?
#"fullscreen on\r\n"
#"fullscreen off\r\n")))
(doc (subsection "Misc. Info"))
(doc (defproc (vlc-get-title (#:vlc vlc vlc? (current-vlc)))
string?
(para "Get the title of the current stream. For example, a particular
DVD, might give behavior like:")
(racketinput
(vlc-get-title)
#,(racketresult "WEST_WING_S7_D3"))
(para "Warning: Season 7 is not the best season for West Wing.")))
(provide vlc-get-title)
(define (vlc-get-title #:vlc (vlc (current-vlc)))
(%vlc:command-with-string-output 'vlc-get-title
vlc
#"get_title\n"))
(define (%vlc:parse-vlc-status-output bstr)
(let ((bstr-len (bytes-length bstr)))
(let loop ((start 0))
(if (= start bstr-len)
'()
(cond ((regexp-match-positions #rx#"^\\( ([^ :][^:]*): *"
bstr
start)
=> (lambda (m)
(let ((val-start (cdar m))
(name-posn (list-ref m 1)))
(cond ((regexp-match-positions #rx#" \\)\r?\n" bstr val-start)
=> (lambda (m)
(let ((val-end (caar m))
(start (cdar m)))
(cons (cons (subbytes bstr (car name-posn) (cdr name-posn))
(subbytes bstr val-start val-end))
(loop start)))))
(else (error '%vlc:parse-vlc-status-output
"could not match end of colon line at position ~S in ~S"
val-start
bstr))))))
((regexp-match-positions #rx#"^\\( ([a-z]+) ([a-z]+) \\)\r?\n"
bstr
start)
=> (lambda (m)
(let ((name-posn (list-ref m 1))
(val-posn (list-ref m 2))
(start (cdar m)))
(cons (cons (subbytes bstr (car name-posn) (cdr name-posn))
(subbytes bstr (car val-posn) (cdr val-posn)))
(loop start)))))
(else (error '%vlc:parse-vlc-status-output
"could not match line at position ~S in ~S"
start
bstr)))))))
(module+ test
(test (%vlc:parse-vlc-status-output
(bytes-append
#"( new input: file:///home/scotty/sheep.mp4 )\r\n"
#"( audio volume: 287 )\r\n"
#"( state paused )\r\n"))
'((#"new input" . #"file:///home/scotty/sheep.mp4")
(#"audio volume" . #"287")
(#"state" . #"paused"))))
(doc (defproc (vlc-status (#:vlc vlc vlc? (current-vlc)))
(list-of (cons/c bytes? bytes?))
(para "Yields an alist of some information about current status. The "
(italic "car")
" of each pair of the alist is a byte string of one of the
following attribute names, and the "
(italic "cdr")
" is a byte string of the attribute value:")
(itemlist
(item (racket #"new input")
" -- URL of the current playlist item.")
(item (racket #"audio volume")
" -- number representing the audio volume.")
(item (racket #"state")
" -- play state; possibly including the following values: "
(racket #"playing")
", "
(racket #"paused")
", "
(racket #"stopped")
"."))
(para "Which attributes are included depends on VLC.")))
(provide vlc-status)
(define (vlc-status #:vlc (vlc (current-vlc)))
(%vlc:parse-vlc-status-output
(%vlc:command-with-output 'vlc-status
vlc
#"status\n")))
(doc (section "Snapshots"))
(doc (defproc (vlc-snapshot (#:vlc vlc vlc? (current-vlc)))
void?
(para "Write a snapshot still image of the current video display to a
file. See VLC documentation for command line arguments for controlling where
and how these files are written, such as "
(tt "--snapshot-path")
".")))
(provide vlc-snapshot)
(define (vlc-snapshot #:vlc (vlc (current-vlc)))
(%vlc:command-without-output 'vlc-snapshot
vlc
#"snapshot\n"))
(doc (section "Exiting"))
(doc (defproc (vlc-shutdown (#:vlc vlc vlc? (current-vlc)))
void?
(para "Terminate the VLC process in an orderly fashion.")))
(provide vlc-shutdown)
(define (vlc-shutdown #:vlc (vlc (current-vlc)))
(%vlc:command-with-ignored-output 'vlc-shutdown
vlc
#"shutdown\n")
(set-vlc-live?! vlc #f)
(void))
(doc (section "Other Operations")
(para "In addition to the procedures that correspond to VLC RC commands,
there are some additional procedures that are built atop RC commands."))
(define (wait-for-vlc-status-state state-bytes
#:delay (delay 0.1)
#:vlc (vlc (current-vlc)))
(let loop ()
(cond ((assoc #"state" (vlc-status #:vlc vlc))
=> (lambda (pair)
(if (equal? (cdr pair) state-bytes)
(void)
(begin (sleep delay)
(loop)))))
(else (sleep delay)
(loop)))))
(doc (defproc (wait-for-vlc-active-playing
(#:delay delay (and/c real? (not/c negative?)) 0.1)
(#:vlc vlc vlc? (current-vlc)))
void?
(para "Wait for VLC to be actively playing, by which we mean that the
stream has actually started playing, not just the RC "
(tt "status")
" command indicating "
(tt "state: playing")
", when, say, the DVD hasn't actually started playing. This seems
to be important for some other operations to take effect, such as seeking in
some cases.")
(para "Note that this procedure is currently protocol-intensive with the
RC interface. "
(racket delay)
" is the number of seconds to pause in between repeatedly sending
some RC messages. By default, it is "
(racket 0.1)
", meaning one tenth of a second.")))
(provide wait-for-vlc-active-playing)
(define (wait-for-vlc-active-playing #:delay (delay 0.1)
#:vlc (vlc (current-vlc)))
(wait-for-vlc-status-state #"playing" #:delay delay)
(let ((first-time (vlc-get-time #:vlc vlc)))
(sleep delay)
(let loop ()
(wait-for-vlc-status-state #"playing" #:delay delay)
(if (equal? (vlc-get-time #:vlc vlc)
first-time)
(begin (sleep delay)
(loop))
(void)))))
(doc (section "Known Issues")
(itemlist
(item "Finish implementing RC commands.")
(item "Need to verify that RC uses UTF-8, and consistently.")
(item "Should try to verify existence of objects before being added to
the playlist, since otherwise VLC can keep trying them continuously and
flooding with repeated error messages.")
(item "The protocol parsing is pretty good, but could still be improved.
In particular, for some messages, it would be better to make the message end
detection sensitive to the syntax of the message. Before doing that, verify
that RC uses UTF-8 consistently.")
(item "Add a "
(racket exn:fail:vlc)
" exception, for ease of handling errors from the protocol, such as
error-message output from RC commands. Currently, these are raised as "
(racket exn:fail)
".")
(item "Make "
(racket vlc-status)
" return strings instead of byte strings, after making sure UTF-8 is consistent.")))
(doc history
(#:planet 1:2 #:date "2012-09-27"
(itemlist
(item "Documented that VLC 2.0.3 RC does not work on Windows,
so this package does not support Windows.")))
(#:planet 1:1 #:date "2012-09-27"
(itemlist
(item "When "
(racket start-vlc)
" can't find VLC in the executable search path, it will
then try a few ``known suspect'' paths, including the standard one for Mac OS
X. (Thanks to Greg Hendershott for reporting.)")
(item "Documentation for "
(racket start-vlc)
" regarding custodians has been corrected. (Thanks to
Greg Hendershott for reporting.)")
(item "Updated documentation to say that this package has been
reported to work on Mac OS X and Microsoft Windows XP.")))
(#:planet 1:0 #:date "2012-09-22"
(itemlist
(item "Preliminary release for testing some of the functionality on
various host platforms and with various VLC versions in use. Not all commands
are implemented, and little testing has been done."))))
![[logo]](/logo.png){kind=logo}