Fwd: Video backend selection

Wed Jan 5 15:58:51 GMT 2022

Wrong sender address..

-------- Forwarded Message --------
Subject: 	Re: Video backend selection
Date: 	Wed, 5 Jan 2022 16:45:22 +0100
From: 	Jesper K. Pedersen <jesper.pedersen at kdab.com>
To: 	Andreas Schleth <schleth_es at web.de>, kphotoalbum at kde.org

Uhh lots of emails six month after the feature his git :-)

See comments inline.

On 1/5/22 00:29, Andreas Schleth wrote:
> Hi,
>
> you know, that I greatly appreciate your work in KPA, but in the case of
> video playback I do not fully understand why the internal video viewer
> exists in the first place. Is it unthinkable to dump the internal viewer
> and instead repurpose the "open with external program" dialog (wrap it
> internally, with a config option and optionally a detection module) and
> just call VLC, mplayer or whatever video player is installed. There is
> probably no system around without any video player. If you need to
> install one of the backends anyway, the GUI would be there too. I think
> along similar lines as why we have no image manipulation options in KPA:
> there are programs around that do a great job at this - Gimp, Darktable,
> you name it. (Except for the old promise: "Kimdaba does not touch your
> files").

Well, KPA also has an image viewer, despite there exists good image 
viewers out there.

I can think of a few reasons to keep the video playback inside KPA:
1) Being able to see tags above your videos
2) Being able to add tokens on your videos and delete them from the DB 
while viewing them
3) Taking the screenshot for us of the video.
4) controlling placement - if we just started VLC we wouldn't be able to 
know where the windows showed up
5) being able to run slide shows with videos and images - if i spawned 
VLC I wouldn't know when it was done.

Of course had I started today I might have reconsidered not implementing 
a video viewer, but 15 years ago there was the great promise of Phonon 
doing it all, and at least IIRC much less external videos viewers.

>
> As Jesper pointed out in another post: it is a lot of work to
> re-implement all gui features of a full blown video player. The keyword
> is "re-". I just had another look and found a lot of new(? or new found)
> features integrated in the RMB menu. Still, while the features present
> in the integrated viewer right now are quite a lot better than a while
> ago, they are still far from perfect, so why bother...? The effort spent
> on the video viewer seems to me a lot like re-inventing the wheel. So,
> why not slim down the code base at this point?
>
> I may simply not understand why KPA really needs an integrated video
> player (this might well be *my* problem). Loading time? Process
> overhead? ...?  I only use the external program option (and am happy for
> having it!) for viewing video anyway and only look at the internal
> player for testing. OK: the tags and categories are only shown with the
> internal version and the option to choose a customized thumbnail is a
> unique feature ... but still ... If you have a few 1000 videos in the
> database, you probably are just as content with being able to select one
> of the autogenerated videothumbnails.
> I still miss the option to select or switch audio channels and the many
> other features I learned to love in VLC and I understand, that this
> would be a lot of implementation effort - and other people might have
> other pain points (subtitles anyone?).
> A compromise might be to include the existing internal viewer in the
> choices for a default video player in the settings dialog.

Right, I like that idea: Among the three others simply have a launch 
external every time. Of course at the cost of not having all of the 
above (tokens, showing tags, playing slideshow, making screenshot)

Would that work for you?

>
> As for the original UX question:
>
> The first time I tested it, I clicked the one time dialog away too
> quickly 

*sniff* and here I though KPA users was better than that :-D

Put I take your point.

> (nobody reads, understands and remembers dialogs if not forced
> to :-) and then found the option to choose the backend in the viewer
> settings. However, when switching backends (at one time I had all 3
> options available) I never found any difference in the behaviour of the
> player. Did I not look closely enough? So, why bother. 

Well you for sure was lucky then. Phonon crashed on me for every few 
videos nevertheless how hard I tried installing different backends
QtAV was pretty awesome, every video played, had nice feature set etc, 
only problem was that it got out of sync with the audio. I asked the 
developer for help, but never heard back
VLC was also pretty good, BUT it didn't (when I looked at it) support 
wayland, so had you chosen that, the video would show up outsite of 
KPA's window.

> If it plays it
> plays. (To be honest, I was quite disappointed at that time as in my
> naivety I expected to find a VLC backend with all the bells and whistles
> of VLC - never mind!)
> Only if it doesn't play (or, beware, crashes), the user needs to find an
> option to remedy the situation. And then, the backends may all use the
> same deficient libavcodec. So, the problem might not be fixable inside
> KPA at all. I had situations when a certain video would only play in
> Mplayer and nothing else. This could only be fixed by carefully
> reinstalling the proper codec libraries. Therefore, some documentation
> for troubleshooting would go a long way.
>
> Therefore, my vote goes to "autodetect" with the option to choose in the
> settings dialog.

Right, I'm still a bit torn, I can see how noone will ever see the 
dialog, I just fear whether they will ever find their way to change the 
backend.

Maybe add an entry to the overcrowded context menu saying "change video 
backend" would help.

Thoughts?

Cheers and thanks for the feedback.

>
> Best regards, Andreas
>
>
> Am 04.01.22 um 19:38 schrieb Jesper K. Pedersen:
>> I don't feel strong either way.
>>
>> The dialog is a one time dialog that shows up as you upgrade KDV, and
>> given the trouble that all three plugins have I think the user should
>> know what he chooses otherwise he will just end up wondering why the
>> preview doesn't work all of a sudden (if you switch from QtAV to one
>> of the other backends behind his back).
>>
>> But again, I don't feel strong about it. Maybe at least inform him
>> that you are switching backend when doing so, and offer him the config
>> dialog
>>
>> Cheers
>> Jesper.
>>
>> On 1/4/22 00:53, Johannes Zarl-Zierl wrote:
>>> Hi!
>>>
>>> I'm not yet totally pleased with the way the user is prompted to
>>> choose a
>>> video player backend.
>>>
>>> So instead of prompting right away I thought that maybe just choosing a
>>> sensible default would be a nicer user experience (currently the first
>>> available of VLC > QtAV > Phonon).
>>>
>>> Since there have been reports with some players crashing outside of
>>> KPHotoAlbums control, I've also added a crash detection: if KPA
>>> terminated
>>> during video playback, it automatically selects a different video
>>> player next
>>> time. As a last resort, the selection dialog is shown.
>>>
>>> I've not yet commited the change to master, but I would like some
>>> feedback
>>> regarding the UX. What do you think?
>>>
>>> The feature is currently in branch work/jzarl/crash-sentinel
>>>
>>> https://invent.kde.org/graphics/kphotoalbum/-/commit/
>>> 78cfa242b9972792eee4661466508beed66b37aa
>>>
>>> Cheers,
>>>    Johannes
>>>
>>>
-- 
Jesper K. Pedersen |jesper.pedersen at kdab.com
HR Director / COO
Klarälvdalens Datakonsult AB, a KDAB Group company
Tel. Direct: +45 2726 8078, Sweden (HQ) +46-563-540090
KDAB - The Qt, C++ and OpenGL Experts
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