fix(viewer): pre-parse media to reduce VLC playback startup gap

[nicomiguelino]

Issues Fixed

• Partially addresses [BUG] Transition issue between slides or at the end of any video #2735
• Reduces the blank screen gap between video transitions on Pi 1-4

Description

Calls get_media().parse() in VLCMediaPlayer.set_asset() to pre-load file metadata before play() is invoked. This gives VLC a head start on opening the file and reading codec info, reducing the startup delay that causes the visible blank screen between slides.

Checklist

• I have performed a self-review of my own code.
• New and existing unit tests pass locally and on CI with my changes.
• I have done an end-to-end test for Raspberry Pi devices.
• I have tested my changes for x86 devices.
• I added a documentation for the changes I have made (when necessary).

[Copilot]

Pull request overview

This PR aims to reduce the visible blank gap when transitioning into VLC-played videos (notably on Raspberry Pi 1–4) by pre-parsing VLC media metadata during VLCMediaPlayer.set_asset() before play() is invoked.

Changes:

• Pre-parse the current VLC media (get_media().parse()) immediately after set_mrl() and audio device selection.

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud