From 6701c3fe4c0a0e1120eddc5cecc7a4c7a34bc4ed Mon Sep 17 00:00:00 2001 From: Ralph Ronnquist Date: Mon, 1 May 2023 14:11:28 +1000 Subject: [PATCH] fixup of comments --- alsa-dispatcher.lsp | 59 +++++++++++++++++++++++++++++++++++---------- 1 file changed, 46 insertions(+), 13 deletions(-) diff --git a/alsa-dispatcher.lsp b/alsa-dispatcher.lsp index df8863b..2439aec 100755 --- a/alsa-dispatcher.lsp +++ b/alsa-dispatcher.lsp @@ -1,8 +1,38 @@ #!/usr/bin/newlisp -;; This is the main script for the pcm-dispatch tool -;; last main-arg nominates the configuration file - +;; This script implements dispacth of stdin via first available for +;; ALSA pcm listed in $HOME/.alsa-dispatcher +;; +;; Debug testing, eg +;; IN=/usr/share/sounds/alsa/Rear_Left.wav +;; sox $IN -r48000 -esigned -es-b16 -c2 x.wav | ./alsa-dispatcher +;; o.e. send audio in format [48000 Hz S16_LE stereo wav] to the program +;; +;; Installation requires ALSA configuration, e.g. in ~/.asoundrc, like +;; (replace $PROGRAM with the program's full pathname) +;; ---- +;; pcm.dispatch { +;; type asym +;; playback { +;; pcm { +;; type plug +;; slave { +;; pcm "file:|exec $PROGRAM" +;; format S16_LE; channels 2; rate 48000 +;; } +;; } +;; } +;; capture plughw +;; } +;; ---- +;; $ aplav -D dispatch /usr/share/sounds/alsa/Rear_Left.wav +;; +;; Maybe setup "dispatch" as default +;; ---- +;; pcm.!default dispatch +;; ---- + +(constant 'DEBUG nil) ;; Set to true to get stdout/stderr while degugging ; ############################################################ ; misc API (signal 1 (fn (x) (exit 0))) @@ -38,13 +68,14 @@ ) ; Return value of configuration setting KEY for plug PCM, or DEFAULT. +; Only"latency=N" is possible; default 100000 (microseconds). (define (cfg-lookup PCM KEY DEFAULT) (if (if (assoc PCM CFGMAP) (lookup KEY $it)) (read-expr $it) DEFAULT)) ; ############################################################ ; libc API -(constant 'libc.so.6 "/lib/x86_64-linux-gnu/libc.so.6") ; https://www.gnu.org/software/libc/manual/html_mono/libc.html +(constant 'libc.so.6 "/lib/x86_64-linux-gnu/libc.so.6") ;; (dup2 OLDFD NEWFD) - Duplicate file descriptor OLDFD onto NEWFD, ;; closing the latter first if open. @@ -55,11 +86,11 @@ ; ############################################################ ; libasound API -(constant 'libasound.so "/usr/lib/x86_64-linux-gnu/libasound.so") ; https://www.alsa-project.org/alsa-doc/alsa-lib/ ; /usr/include/asm-generic/errno-base.h +(constant 'libasound.so "/usr/lib/x86_64-linux-gnu/libasound.so") -;; Used constants +;; Selected libasound constants (constant 'SND_PCM_STREAM_PLAYBACK 0 'SND_PCM_MODE_BLOCK 0 ; this mode label is invented here @@ -67,22 +98,24 @@ 'SND_PCM_ACCESS_RW_INTERLEAVED 3 ) -;; (snd_pcm_close PCM) - Close PCM handle. Closes the given PCM handle -;; and frees all associated resources. +;; (snd_pcm_close PCM) - Close PCM. Closes the given PCM and frees all +;; associated resources. (import libasound.so "snd_pcm_close" "int" "void*" ; snd_pcm_t *pcm ) ;; (snd_pcm_drain PCM) - Stop PCM whilst preserving pending frames. -;; For playback wait for all pending frames to be played and then stop -;; the PCM. For capture stop PCM permitting to retrieve residual +;; For playback: wait for all pending frames to be played and then +;; stop the PCM. For capture: stop PCM permitting to retrieve residual ;; frames. (import libasound.so "snd_pcm_drain" "int" "void*" ; snd_pcm_t *pcm ) ;; (snd_pcm_open NAME STREAM MODE) - Opens a PCM and returns its -;; handle or nil. Actual error code is discarded. +;; address or nil. Any actual error code is discarded. +; Need wrapping so as to provide a memory slot for the returned PCM +; address. Newlisp doesn't support call-by-reference parameters well. (letex ((IMP (import libasound.so "snd_pcm_open" "int" "void*" ; snd_pcm_t **pcmp [output] "char*" ; const char *name @@ -95,7 +128,7 @@ (when (= (IMP PCM NAME STREAM MODE)) ((unpack "Lu" PCM) 0)))))) ;; (snd_pcm_set_params PCM FMT ACCESS CH RATE RESAMPLE LATENCY) - Set -;; the hardware and software parameters in a simple way. +;; hardware and software parameters in a simple way. (import libasound.so "snd_pcm_set_params" "int" "void*" ; snd_pcm_t *pcm "int" ; snd_pcm_format_t format @@ -133,7 +166,7 @@ ; The main program ; redirect stdout/err to /dev/null (flagged for debugging purposes) -(when true +(when (not DEBUG) (let ((REDIR (open "/dev/null" "append"))) (when (< REDIR) (exit 1)) (when (< (dup2 REDIR 2)) (exit 1)) -- 2.39.2