Need clarification on gstcolorbalance

[Yogesh Marwaha]

Hi,

I'm trying to add options of contrast, brightness etc. in my app.
GStreamer's videobalance and xvimagesink elements support
GstColorBalance interface. But in case of xvimagesink, I'm unable
to get a list of channels.

Following is the code snippet I'm using: -

    GstElement *a = gst_element_factory_make("xvimagesink",
"gravity-playbin-video-a");
    if(GST_IS_COLOR_BALANCE(a)){
        qDebug() << "Color balance.";
        const GList * channels =
gst_color_balance_list_channels(GST_COLOR_BALANCE(a));
        if(!channels)
            qDebug() << "Channels is null.";
        while ( channels ) {
            qDebug() << "Channel name:" <<
GST_COLOR_BALANCE_CHANNEL(channels->data)->label;;
            channels = g_list_next(channels);
        }
    }else{
        qDebug() << "No color balance.";
    }

    GstElement *b = gst_element_factory_make("videobalance",
"gravity-playbin-video-b");
    if(GST_IS_COLOR_BALANCE(b)){
        qDebug() << "Color balance.";
        const GList * channels =
gst_color_balance_list_channels(GST_COLOR_BALANCE(b));
        if(!channels)
            qDebug() << "Channels is null.";
        while ( channels ) {
            qDebug() << "Channel name:" <<
GST_COLOR_BALANCE_CHANNEL(channels->data)->label;;
            channels = g_list_next(channels);
        }
    }else{
        qDebug() << "No color balance.";
    }


Here is the output: -
Color balance.
Channels is null.
Color balance.
Channel name: "HUE"
Channel name: "SATURATION"
Channel name: "BRIGHTNESS"
Channel name: "CONTRAST"


What could be the cause of problem? How should I do it properly?

Regards,

Yogesh Marwaha