QtMultiMedia property bindings not working initially

REPRODUCIBILITY (% or how often): 100%
BUILD ID = OS VERSION (Settings > About product): 4.2
HARDWARE (XA2, X10, X10 II, …): XA2
UI LANGUAGE:DE
REGRESSION: (compared to previous public release: Yes, No, ?): ?

DESCRIPTION:

The playbackRate, duration and position property bindings in QTMultiMedia do not work as expected. It seems like there is a missing initial update on them.

PRECONDITIONS:

Create an application with this Page:

import QtQuick 2.0
import Sailfish.Silica 1.0
import QtMultimedia 5.6

Page {
id: page

// The effective value will be restricted by ApplicationWindow.allowedOrientations
allowedOrientations: Orientation.All

// To enable PullDownMenu, place our content in a SilicaFlickable
Slider {
    width: parent.width
    height: Theme.itemSizeLarge
    maximumValue: myMedia.duration
    value: myMedia.position
}

MediaPlayer {
    id: myMedia
    source: "https://ia601602.us.archive.org/13/items/FurEliseLudwigVanBeethoven/fur%20elise%20%28Ludwig%20van%20Beethoven%29.ogg"
    playbackRate: 2
    autoPlay: true
}
}

STEPS TO REPRODUCE:

  1. Open the page
  2. listen
  3. check the slider
  4. change the url to a local file
  5. open the page
  6. listen

EXPECTED RESULT:

For both runs: The slider position moves according to the playback. The playback is twice as fast.

ACTUAL RESULT:

The playbackRate is normal on streaming, but double speed when playing a local file.
I could not observe this with this example yet, but sometimes, the slider is not moving as well (probably duration is not updated properly).

If there are any known workarounds, I’d be happy to know them. But it would be very nice if this would be fixed.