screenshare: drop mpv --untimed so shared video stays A/V-synced

The viewer launched mpv with `--untimed`, which displays each video
frame the instant it decodes and ignores audio timestamps. Sharing a
desktop (no audio) that just minimizes latency, but sharing a *video*
made its audio drift progressively out of sync — confirmed in a field
test watching a video together. Remove the flag so mpv paces video to
the audio clock; the remaining low-latency flags keep lag negligible for
desktop pointing.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packaging/PKGBUILD

@@ -1,7 +1,7 @@
 # Maintainer: mollusk <jitty+lc1iz0dc@protonmail.com>
 pkgname=peerspeak-git
 _pkgname=peerspeak
-pkgver=0.6.1.r315.ga78860d
+pkgver=0.6.2.r319.g8014edf
 pkgrel=1
 pkgdesc="Decentralized peer-to-peer voice chat (Rust/iroh/PipeWire/Opus/iced)"
 arch=('x86_64')

src/screenshare/mod.rs

@@ -547,13 +547,19 @@ fn event_for_log(ev: &PixelpassEvent) -> String {
     }
 }
 
-/// Open the viewer stream URL in a media player. Mirrors pixelpass's own
+/// Open the viewer stream URL in a media player, then fall back to vlc. The
-/// low-latency mpv invocation; falls back to vlc. The player is reaped in a
+/// player is reaped in a background task so it doesn't linger as a zombie when
-/// background task so it doesn't linger as a zombie when its window closes.
+/// its window closes.
+///
+/// The flags keep latency low while preserving A/V sync. We deliberately do
+/// NOT pass mpv's `--untimed`: that displays each video frame the instant it
+/// decodes, ignoring audio timestamps, which makes a shared *video* drift
+/// progressively out of sync with its audio. Pacing to the audio clock costs a
+/// little latency (negligible for pointing at a desktop) and keeps a shared
+/// video in sync.
 fn launch_player(url: &str) -> std::io::Result<()> {
     const MPV_ARGS: &[&str] = &[
         "--profile=low-latency",
-        "--untimed",
         "--hwdec=auto",
         "--audio-buffer=0.2",
         "--demuxer-max-bytes=2M",