Re: Recovering playback state of multiple playlists and over multiple sessions

[Yuchen Pei]

Something seems to be weird with my email client - sorry for the 
duplicate.

Yoni Rabkin <yoni@rabkins.net> writes:

> Yuchen Pei <hi@ypei.me> writes:
>
> > Yoni Rabkin <yoni@rabkins.net> writes:
> >
> > > Mike Kazantsev <mk.fraggod@gmail.com> writes:
> > >
> > > > On Wed, 20 Oct 2021 08:35:07 -0400
> > > > Yoni Rabkin <yoni@rabkins.net> wrote:
> > > >
> > > >
> > > > Maybe emms can just always store/update emms-playing-time on 
> > > > the
> > > > track
> > > > in playlist?
> > > >
> > > > That'd also double as "last stopped time" without adding any 
> > > > really
> > > > new
> > > > concepts, and there's 'info-playing-time for total duration 
> > > > there
> > > > already.
> > > >
> > > >
> > > > Otherwise implementation like this jumps to mind:
> > > >
> > > >   (funcall (emms-player-get emms-player-playing-p
> > > > 'query-position))
> > > >
> > > > It's what mpv currently does in response to events, and 
> > > > presumably
> > > > backends that only get it from somewhere periodically 
> > > > (e.g. stdout
> > > > status line) can just cache it in some value.
> > > >
> > > > But if this is not implemented for backend, I'd think that 
> > > > fallback
> > > > to
> > > > emms-playing-time would seem reasonable, and then why not 
> > > > just
> > > > always
> > > > store that in the first place? :)
> > >
> > > There is no reason not to do that; it wouldn't impact 
> > > anything.
> >
> > Great.  Now the question is who is going to submit a patch for 
> > this?
> > I can do it if you want.
>
> Patches are always welcome here; we have an "open-door" policy 
> to
> welcome sojourning code.

Please find attached a patch to add this facility and let me know 
what you think.

From fd37f9c452d615e42c2768a3a81a6700335f66d5 Mon Sep 17 00:00:00 2001
From: Yuchen Pei <hi@ypei.me>
Date: Thu, 25 Nov 2021 15:06:32 +1100
Subject: [PATCH] Adding a facility to resume from where the playback left at.

- A custom option emms-playing-time-resume-from-last-played, default
to nil, that resumes to the playing time when the track is started
again.
- Internally, emms-playing-time will update the playing-time property
of the track, and reset it to nil when a track is finished.
---
 emms-playing-time.el | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/emms-playing-time.el b/emms-playing-time.el
index e2a02fb..5a674b6 100644
--- a/emms-playing-time.el
+++ b/emms-playing-time.el
@@ -65,6 +65,11 @@ Valid styles are `time' (e.g., 01:30/4:20),
 and `downtime' (e.g. -03:58)."
   :type 'symbol)
 
+(defcustom emms-playing-time-resume-from-last-played nil
+  "If set to Non-nil, emms will resume / seek to
+ the last playing time when the track is started again."
+  :type 'boolean)
+

 ;;; Emms Playing Time
 
@@ -123,6 +128,15 @@ and `downtime' (e.g. -03:58)."
   (declare (obsolete emms-playing-time-mode "Apr 2021"))
   (emms-playing-time-mode (if (and arg (> arg 0)) 1 -1)))
 
+(defun emms-playing-time-track-reset ()
+  (emms-track-set (emms-playlist-current-selected-track)
+                 'playing-time nil))
+
+(defun emms-playing-time-maybe-seek-to-last-played ()
+  (when-let ((last-playing-time
+             (emms-track-get (emms-playlist-current-selected-track)
+                             'playing-time)))
+    (emms-seek-to last-playing-time)))
 
 (define-minor-mode emms-playing-time-mode
   "Turn on emms playing time if ARG is positive, off otherwise.
@@ -144,19 +158,28 @@ could call `emms-playing-time-enable-display' and
        (emms-playing-time-mode-line)
        (add-hook 'emms-player-started-hook       #'emms-playing-time-start)
        (add-hook 'emms-player-stopped-hook       #'emms-playing-time-stop)
+       (add-hook 'emms-player-finished-hook
+                 #'emms-playing-time-track-reset)
        (add-hook 'emms-player-finished-hook      #'emms-playing-time-stop)
        (add-hook 'emms-player-paused-hook        #'emms-playing-time-pause)
        (add-hook 'emms-player-seeked-functions   #'emms-playing-time-seek)
-       (add-hook 'emms-player-time-set-functions #'emms-playing-time-set))
+       (add-hook 'emms-player-time-set-functions #'emms-playing-time-set)
+       (when emms-playing-time-resume-from-last-played
+         (add-hook 'emms-player-started-hook
+                   #'emms-playing-time-maybe-seek-to-last-played)))
     (setq emms-playing-time-display-mode nil)
     (emms-playing-time-stop)
     (emms-playing-time-restore-mode-line)
     (remove-hook 'emms-player-started-hook       #'emms-playing-time-start)
     (remove-hook 'emms-player-stopped-hook       #'emms-playing-time-stop)
     (remove-hook 'emms-player-finished-hook      #'emms-playing-time-stop)
+    (remove-hook 'emms-player-finished-hook
+                #'emms-playing-time-track-reset)
     (remove-hook 'emms-player-paused-hook        #'emms-playing-time-pause)
     (remove-hook 'emms-player-seeked-functions   #'emms-playing-time-seek)
-    (remove-hook 'emms-player-time-set-functions #'emms-playing-time-set)))
+    (remove-hook 'emms-player-time-set-functions #'emms-playing-time-set)
+    (remove-hook 'emms-player-started-hook
+                #'emms-playing-time-maybe-seek-to-last-played)))
 
 ;;;###autoload
 (define-minor-mode emms-playing-time-display-mode
@@ -180,6 +203,8 @@ could call `emms-playing-time-enable-display' and
 (defun emms-playing-time-display ()
   "Display playing time on the mode line."
   (setq emms-playing-time (round (1+ emms-playing-time)))
+  (emms-track-set (emms-playlist-current-selected-track)
+                 'playing-time emms-playing-time)
   (setq emms-playing-time-string
         (if (null emms-playing-time-display-mode)
             ""
-- 
2.34.0


--
Best,
Yuchen

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