Audio Source Problem

Description about the Audio Problem :
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1.within the Audio source Filter we set the config as follows: i)Sampling Frequency is 48KHz ii) we set the timestamp as follows from the RTP packet as follows:
m_rtStart = m_rtStop; m_rtStop = m_iRTPPacketTimestamp ;
the difference between m_rtStart and m_rtStop is 15200.
AudioFrameNo StartTime Stop Time
1 0 15120
2 15120 30240
3 30240 45360 and so on
within the Source Filter, we dumped the received audio data to an Mp2 file without timestamp information. if we played the Mp2 file, it was working well.
2.ffmpeg command for capturing data from audio source as follows:
ffmpeg -f audio_device -i /dev/dsp -acodec -mp2 -ar 48000 -ab 64kb -f rtp rtp://192.168.1.198:5001/