Questions regarding MediaPlayList

[Matthieu Gallien]

Hello,

On mercredi 9 mai 2018 20:56:24 CEST Alexander Stippich wrote:
> Hello,
> 
> I'm slowly working towards handling files with little to zero metadata,
> which is needed for a file browser. I'm struggling a little bit with the
> mediaplaylist currently, specifically with tracks enlisted only by url.

Could you share your feature branch such that others can look at it ? You did 
that for HighDPI and in my opinion, it has worked well.

> I never really understood the duplication between the MediaPlaylistEntry
> data lists and the lists of MusicAudioTracks, can you elaborate a little
> bit on that?

My main idea is to have the playlist store its tracks independently of where 
they are. They could be in the local music database or in an UPnP/DLNA share 
or from a local file or somewhere else. It is also possible that an existing 
track in the playlist has been moved to another path.
If we store the tracks by their path, we cannot restore a playlist with a 
track for which the path is not the same.
To allow for more flexibility, I had added the possibility to also have tracks 
being identified by their path. This should be working fine but force to 
compute their metadata after the tracks has been added.

> Anyways, there is a bug that also affects enlisting tracks via the command
> line.
> If you add the tracks via url, they get added to the mData structure with a
> corresponding, empty MusicAudioTrack (I think). This makes displaying etc.
> really difficult and currently completely fails. The scanning of metadata is
> only happening afterwards, since the url is given to the TracksListener,
> which does the scanning for metadata. It seems that it is not updated
> afterwards.

Yes, fetching the metadata should be asynchronous. It should be the case when 
you want to queue a track by its path instead of by its metadata. What is the 
problem you are seeing ?

> I think we need to fill the MusicAudioTrack immediately, I'm just not sure
> how to do it properly. One could move the scanning to MediaPlayList, but I
> think this would block the UI. Thoughts?

You cannot fill the MusicAudioTrack immediately in the main thread. Reading 
metadata via KFileMetaData takes some time and the delay should be noticeable.

> Best regards,
> Alex
> 
> 
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Best regards

--
Matthieu Gallien