fix video delay 4s

[vc60er]

Issue #, if available:

#1105

Description of changes:

change gstreamer pipeline param framerate to 25/1.

Because the SAMPLE_VIDEO_FRAME_DURATION used for accumulate the videoTimestamp is calculated from assume video fps is 25, which definition can be find in Samples.h, so update the video framerate to 25/1.

The framerate of video

// kvsWebRTCClientMasterGstreamerSample.c
gst_parse_launch("autovideosrc ! queue ! videoconvert ! video/x-raw,width=1280,height=720,framerate=[30/1,10000000/333333] ! "

The definition of SAMPLE_VIDEO_FRAME_DURATION

# Samples.h
#define DEFAULT_FPS_VALUE                        25
#define SAMPLE_VIDEO_FRAME_DURATION (HUNDREDS_OF_NANOS_IN_A_SECOND / DEFAULT_FPS_VALUE)

The calculation method of videoTimestamp

// kvsWebRTCClientMasterGstreamerSample.c
GstFlowReturn on_new_sample(GstElement* sink, gpointer data, UINT64 trackid) {
            if (trackid == DEFAULT_AUDIO_TRACK_ID) {
            } else {
                pRtcRtpTransceiver = pSampleStreamingSession->pVideoRtcRtpTransceiver;
                frame.presentationTs = pSampleStreamingSession->videoTimestamp;
                frame.decodingTs = frame.presentationTs;
                pSampleStreamingSession->videoTimestamp += SAMPLE_VIDEO_FRAME_DURATION; // assume video fps is 25
            }
}

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[disa6302]

@vc60er ,

Can you direct the PR to develop branch instead?

The base branch was changed.

[vc60er]

@vc60er ,

Can you direct the PR to develop branch instead?

@disa6302 done, I have create a new PR, and closed this.

#1525