import javax.media.rtp.event.RemotePayloadChangeEvent; //导入依赖的package包/类
/**
 * Check whether the payload type of the current packet is different from
 * the previous type on this SSRC.  If it's changed, stop the data source
 * and fire a <tt>RemotePayloadChangeEvent</tt> so that the
 * <tt>MediaStream</tt> will reprogram the codec chain for the new codec.
 *
 * @param rtpPacket The current RTP packet to check
 * @param ssrcinfo The existing SSRC info
 */
private void performMisMatchedPayloadCheck(RTPPacket rtpPacket,
                                           SSRCInfo ssrcinfo)
{
    if (ssrcinfo.lastPayloadType != -1 &&
        ssrcinfo.lastPayloadType != rtpPacket.payloadType)
    {
        ssrcinfo.currentformat = null;

        if (ssrcinfo.dsource != null)
        {
            RTPControlImpl rtpcontrolimpl = (RTPControlImpl) ssrcinfo.dsource
                    .getControl(controlName);
            if (rtpcontrolimpl != null)
            {
                rtpcontrolimpl.currentformat = null;
                rtpcontrolimpl.payload = -1;
            }

            try
            {
                StringBuffer buf = new StringBuffer("[");
                for (PushBufferStream aStream : ssrcinfo.dsource.getStreams())
                {
                    buf.append(aStream.hashCode());
                    buf.append(" ");
                }

                buf.append("]");
                Log.warning("Stopping datasource " + ssrcinfo.dsource.hashCode() +
                    " (used by stream(s) " + buf.toString() +
                    ")because of payload type mismatch: expecting pt=" +
                    ssrcinfo.lastPayloadType + ", got pt=" +
                    rtpPacket.payloadType);
                ssrcinfo.dsource.stop();
            }
            catch (IOException ioexception)
            {
                Log.warning("Problem stopping DataSource after PT change " +
                    ioexception.getMessage());
            }
        }

        ssrcinfo.lastPayloadType = rtpPacket.payloadType;

        RemotePayloadChangeEvent remotepayloadchangeevent = new RemotePayloadChangeEvent(
                cache.sm, (ReceiveStream) ssrcinfo,
                ssrcinfo.lastPayloadType, rtpPacket.payloadType);
        cache.eventhandler.postEvent(remotepayloadchangeevent);
    }
}