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Taglib metadata reading, crossfade metadata timing fix 

- Add taglib dependency to cl-streamer/harmony system
- Add read-audio-metadata: reads artist/title/album from FLAC/MP3 tags
- Add format-display-title: builds 'Artist - Title' from tags, falls back to filename
- Add update-all-mounts-metadata: updates ICY metadata on all mount points
- Defer metadata update during crossfade until fade completes (listeners hear correct track)
- Fix play-list wait loop: was nested inside crossfade conditional, first track never waited
- Remove filename-derived :title from test playlist (taglib reads real tags now)
This commit is contained in:
Glenn Thompson 2026-03-03 21:10:44 +03:00
parent 2649a8169a
commit edf9326007
3 changed files with 82 additions and 45 deletions
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3
cl-streamer/cl-streamer.asd
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@ -25,7 +25,8 @@
#:harmony
#:cl-mixed
#:cl-mixed-mpg123
#:cl-mixed-flac)
#:cl-mixed-flac
#:taglib)
:components ((:file "harmony-backend")))
(asdf:defsystem #:cl-streamer/encoder

70
cl-streamer/harmony-backend.lisp
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@ -156,21 +156,58 @@
(log:info "Audio pipeline stopped")
pipeline)
(defun play-file (pipeline file-path &key (mixer :music) title (on-end :free))
(defun read-audio-metadata (file-path)
"Read metadata (artist, title, album) from an audio file using taglib.
Returns a plist (:artist ... :title ... :album ...) or NIL on failure."
(handler-case
(let ((audio-file (audio-streams:open-audio-file (namestring file-path))))
(list :artist (or (abstract-tag:artist audio-file) nil)
:title (or (abstract-tag:title audio-file) nil)
:album (or (abstract-tag:album audio-file) nil)))
(error (e)
(log:debug "Could not read tags from ~A: ~A" file-path e)
nil)))
(defun format-display-title (file-path &optional explicit-title)
"Build a display title for ICY metadata.
If EXPLICIT-TITLE is given, use it.
Otherwise read tags from the file: 'Artist - Title' or fall back to filename."
(or explicit-title
(let ((tags (read-audio-metadata file-path)))
(if tags
(let ((artist (getf tags :artist))
(title (getf tags :title)))
(cond ((and artist title (not (string= artist ""))
(not (string= title "")))
(format nil "~A - ~A" artist title))
(title title)
(artist artist)
(t (pathname-name (pathname file-path)))))
(pathname-name (pathname file-path))))))
(defun update-all-mounts-metadata (pipeline display-title)
"Update ICY metadata on all mount points."
(dolist (output (drain-outputs (pipeline-drain pipeline)))
(cl-streamer:set-now-playing (cdr output) display-title)))
(defun play-file (pipeline file-path &key (mixer :music) title (on-end :free)
(update-metadata t))
"Play an audio file through the pipeline.
The file will be decoded by Harmony and encoded for streaming.
If TITLE is given, update ICY metadata with it.
Otherwise reads tags from the file via taglib.
FILE-PATH can be a string or pathname.
ON-END is passed to harmony:play (default :free)."
ON-END is passed to harmony:play (default :free).
UPDATE-METADATA controls whether ICY metadata is updated immediately."
(let* ((path (pathname file-path))
(server (pipeline-harmony-server pipeline))
(harmony:*server* server)
(display-title (or title (pathname-name path))))
;; Update ICY metadata so listeners see the track name
(cl-streamer:set-now-playing (pipeline-mount-path pipeline) display-title)
(display-title (format-display-title path title)))
(when update-metadata
(update-all-mounts-metadata pipeline display-title))
(let ((voice (harmony:play path :mixer mixer :on-end on-end)))
(log:info "Now playing: ~A" display-title)
voice)))
(values voice display-title))))
(defun voice-remaining-seconds (voice)
"Return estimated seconds remaining for a voice, or NIL if unknown."
@ -214,11 +251,13 @@
(values entry nil))
(handler-case
(let* ((server (pipeline-harmony-server pipeline))
(harmony:*server* server)
(voice (play-file pipeline path :title title
:on-end :disconnect)))
(harmony:*server* server))
(multiple-value-bind (voice display-title)
(play-file pipeline path :title title
:on-end :disconnect
:update-metadata (null prev-voice))
(when voice
;; If this isn't the first track, fade in from 0
;; If this isn't the first track, crossfade
(when (and prev-voice (> idx 0))
(setf (mixed:volume voice) 0.0)
;; Fade in new voice and fade out old voice in parallel
@ -229,23 +268,24 @@
(harmony:stop prev-voice))
:name "cl-streamer-fadeout")))
(volume-ramp voice 1.0 fade-in)
(bt:join-thread fade-thread)))
(bt:join-thread fade-thread))
;; Now the crossfade is done, update metadata
(update-all-mounts-metadata pipeline display-title))
;; Wait for track to approach its end
(sleep 0.5) ; let decoder start
(sleep 0.5)
(loop while (and (pipeline-running-p pipeline)
(not (mixed:done-p voice)))
for remaining = (voice-remaining-seconds voice)
;; Start crossfade when we're within crossfade-duration of the end
when (and remaining
(<= remaining crossfade-duration)
(not (mixed:done-p voice)))
do (setf prev-voice voice)
(return) ; break out to start next track
(return)
do (sleep 0.1))
;; If track ended naturally (no crossfade), clean up
(when (mixed:done-p voice)
(harmony:stop voice)
(setf prev-voice nil))))
(setf prev-voice nil)))))
(error (e)
(log:warn "Error playing ~A: ~A" path e)
(sleep 1)))))

8
cl-streamer/test-stream.lisp
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@ -60,18 +60,14 @@
(let ((files nil))
(dolist (dir (directory (merge-pathnames "*/" *music-dir*)))
(dolist (flac (directory (merge-pathnames "**/*.flac" dir)))
(push (list :file (namestring flac)
:title (format nil "~A - ~A"
(car (last (pathname-directory flac)))
(pathname-name flac)))
files)))
(push (list :file (namestring flac)) files)))
;; Shuffle and take first 10 tracks
(subseq (alexandria:shuffle (copy-list files))
0 (min 10 (length files)))))
(format t "Queued ~A tracks:~%" (length *playlist*))
(dolist (entry *playlist*)
(format t " ~A~%" (getf entry :title)))
(format t " ~A~%" (getf entry :file)))
;; 6. Start playlist playback
(format t "~%[6] Starting playlist...~%")