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

[Yuchen Pei]

Mike Kazantsev <mk.fraggod@gmail.com> writes:

> On Thu, 14 Oct 2021 17:12:50 -0400
> Yoni Rabkin <yoni@rabkins.net> wrote:
>
> > Yuchen Pei <hi@ypei.me> writes:
> >
> > > Yoni Rabkin <yoni@rabkins.net> writes:
> > >  
> > >> `emms-bookmarks' has code to support this, but it isn't 
> > >> extensively
> > >> developed because this is an edge case and doesn't come up 
> > >> very
> > >> often. I
> > >> have used `emms-bookmarks' in the (far) past and I remember 
> > >> it
> > >> working
> > >> well enough at the time.  
> > >
> > > Thanks for the pointer.
> > >
> > > As I understand it emms-bookmarks's goal is to restore the 
> > > playback
> > > position in a media file, but not to restore to the item in a 
> > > playlist
> > > across emacs sessions (my second problem).  I tried 
> > > emms-bookmark-add
> > > on an item, switched to another playlist and played something 
> > > there,
> > > and came back to the item, and did emms-bookmark-next.  It 
> > > didn't
> > > restore the position.  I'll have to look more into it.  
> >
> > The bookmark data is stored natively as part of the track, so 
> > it would
> > be written to disk in a emms-playlist-save, and equally read 
> > back of
> > course.
>
> If mpv player is used, I'd also suspect that immediately 
> restoring
> position might not work due to race with async playback start - 
> e.g.
> "seek" command being sent before playback actually starts in mpv 
> or
> something like that.
>
> Don't think I've tested restoring bookmarks myself, but if it 
> doesn't
> look like tagging issue of some kind, maybe try doing this 
> before
> starting playback/bookmark-restore:
>
>   (setq emms-player-mpv-debug t)
>
> And then check *Messages* buffer to see whether:
>
>  - "seek" command is being sent to mpv at all.
>  - Whether it precedes {"event": "playback-restart"} there.

It does precede playback-restart.  I tried using 
emms-bookmark-next when the track is playing or paused.  Both 
times it sends the seek request and skip to the end of the track.

Here's when I paused the track first:

> emms-player-mpv 441.3 json >> 
> {"command":["set","pause","yes"],"request_id":648}
> emms-player-mpv 441.3 json << 
> {"data":null,"request_id":648,"error":"success"}
> emms-player-mpv 441.3 json << {"event":"pause"} [2 times]
> emms-player-mpv 444.5 json >> 
> {"command":["seek",38214,"absolute"],"request_id":649}
> test
> emms-player-mpv 444.6 json << 
> {"data":null,"request_id":649,"error":"success"}
> emms-player-mpv 444.6 json << {"event":"seek"}
> emms-player-mpv 444.6 json << {"event":"metadata-update"}
> emms-player-mpv 446.3 json << {"event":"playback-restart"}
> emms-player-mpv 446.3 json >> 
> {"command":["get_property","stream-end"],"request_id":650}
> emms-player-mpv 446.4 json << 
> {"data":104699160,"request_id":650,"error":"success"}
> emms-player-mpv 446.4 json >> 
> {"command":["get_property","duration"],"request_id":651}
> emms-player-mpv 446.4 json << 
> {"data":2729.433333,"request_id":651,"error":"success"}

Here's when I started playing the track first:

> emms-player-mpv 42.4 json << {"event":"playback-restart"}
> emms-player-mpv 42.5 json >> 
> {"command":["get_property","stream-end"],"request_id":635}
> emms-player-mpv 42.5 json << 
> {"data":104699160,"request_id":635,"error":"success"}
> emms-player-mpv 42.5 json >> 
> {"command":["get_property","duration"],"request_id":636}
> emms-player-mpv 42.5 json << 
> {"data":2729.433333,"request_id":636,"error":"success"}
> emms-player-mpv 51.6 json >> 
> {"command":["seek",38214,"absolute"],"request_id":637}
> test
> emms-player-mpv 51.7 json << 
> {"data":null,"request_id":637,"error":"success"}
> emms-player-mpv 51.7 json << {"event":"seek"}
> emms-player-mpv 51.7 json << {"event":"metadata-update"}
> emms-player-mpv 53.5 json << {"event":"playback-restart"}
> emms-player-mpv 53.5 json >> 
> {"command":["get_property","stream-end"],"request_id":638}
> emms-player-mpv 53.6 json << {"event":"audio-reconfig"}
> emms-player-mpv 53.6 json << {"event":"video-reconfig"}
> emms-player-mpv 53.7 json << {"request_id":638,"error":"property 
> unavailable"}
> emms-player-mpv 53.8 json << {"event":"tracks-changed"}
> emms-player-mpv 53.8 json << 
> {"event":"end-file","reason":"eof","playlist_entry_id":70}

--
Best,
Yuchen

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