Volume change delay

[Yanov, Andrey]

Hi everyone!

I'm a newbie, and I'm asking for your help with the next problem:
I have a webkit build with GStreamer usage for playing HTML5 video/audio content.
The problem is in a big delay between calling gst_stream_volume_set_volume() and actually receiving audio stream with volume change.
The delay is about 5-8 seconds.
Currently, we are using playbin2 GStreamer component to play the audio/video content.
Here is the link to source file we've based our solution:
http://gitorious.org/webkit/qtwebkit-webkit2-dev/blobs/356a65eae11c560e1953c6cba8c455d5be369a95/WebCore/platform/graphics/gstreamer/MediaPlayerPrivateGStreamer.cpp

I have very unclear understanding how the whole GStreamer system works, I've tried to add explicitly the volume component by:
m_vol = gst_element_factory_make("volume", NULL);
gst_bin_add(GST_BIN(m_playBin), m_vol);

and modifying code to call setVolume for m_vol:

void MediaPlayerPrivateGStreamer::setVolume(float volume) {
    m_vol = gst_element_factory_make("volume", NULL);
    gst_bin_add(GST_BIN(m_playBin), m_vol);
}

But I get the same effect.

Is there a way to find out what's the reason for such a big delay ?
Could it be the reason that volume is not change for already buffered data ?

I'm grateful for any help from you guys.
Thank you,
Andrey Yanov
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