wispcmaudioservermediasubsession.cpp

采用公司系列的芯片

/*
 * Copyright (C) 2005 WIS Technologies International Ltd.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and the associated README documentation file (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
// A "ServerMediaSubsession" subclass for on-demand unicast streaming
// of PCM audio from a WIS GO7007 capture device.
// Implementation

#include "WISPCMAudioServerMediaSubsession.hh"
#include <uLawAudioFilter.hh>
#include <SimpleRTPSink.hh>

WISPCMAudioServerMediaSubsession* WISPCMAudioServerMediaSubsession
::createNew(UsageEnvironment& env, WISInput& wisInput,
	    unsigned samplingFrequency, unsigned numChannels,
	    Boolean inputIsLittleEndian, Boolean convertToULaw) {
  return new WISPCMAudioServerMediaSubsession(env, wisInput,
						  samplingFrequency, numChannels,
						  inputIsLittleEndian, convertToULaw);
}

WISPCMAudioServerMediaSubsession
::WISPCMAudioServerMediaSubsession(UsageEnvironment& env, WISInput& wisInput,
				       unsigned samplingFrequency, unsigned numChannels,
				       Boolean inputIsLittleEndian, Boolean convertToULaw)
  : WISServerMediaSubsession(env, wisInput,
			     fSamplingFrequency*(fConvertToULaw ? 8 : 16)*fNumChannels),
  fSamplingFrequency(samplingFrequency), fNumChannels(numChannels),
  fInputIsLittleEndian(inputIsLittleEndian), fConvertToULaw(convertToULaw) {
}

WISPCMAudioServerMediaSubsession::~WISPCMAudioServerMediaSubsession() {
}

FramedSource* WISPCMAudioServerMediaSubsession
::createNewStreamSource(unsigned /*clientSessionId*/, unsigned& estBitrate) {
  FramedSource* pcmSource = fWISInput.audioSource();
  
  // Add in any filter necessary to transform the data prior to streaming:
  FramedSource* resultSource;
  if (fConvertToULaw) { // stream u-law
    // Add a filter that converts from raw 16-bit PCM audio
    // to 8-bit u-law audio:
    resultSource = uLawFromPCMAudioSource::createNew(envir(), pcmSource);
  } else { // stream raw PCM
    if (fInputIsLittleEndian) {
      // The 16-bit samples are in little-endian order.  Add a filter
      // that converts them to network (i.e., big-endian) order:
      resultSource = EndianSwap16::createNew(envir(), pcmSource);
    } else {
      // The 16-bit samples are already in big-endian order:
      resultSource = pcmSource;
    }
  }

  estBitrate = fEstimatedKbps;
  
  return resultSource;
}

RTPSink* WISPCMAudioServerMediaSubsession
::createNewRTPSink(Groupsock* rtpGroupsock, unsigned char rtpPayloadTypeIfDynamic,
		   FramedSource* /*inputSource*/) {
  setAudioRTPSinkBufferSize();
  char* mimeType;
  unsigned char payloadFormatCode = rtpPayloadTypeIfDynamic; // by default
  if (fConvertToULaw) { // stream u-law
    mimeType = "PCMU";
    if (fSamplingFrequency == 8000 && fNumChannels == 1) {
      payloadFormatCode = 0; // a static RTP payload type
    }
  } else { // stream raw PCM
    mimeType = "L16";
    if (fSamplingFrequency == 44100 && fNumChannels == 2) {
      payloadFormatCode = 10; // a static RTP payload type
    } else if (fSamplingFrequency == 44100 && fNumChannels == 1) {
      payloadFormatCode = 11; // a static RTP payload type
    }
  }

  return SimpleRTPSink::createNew(envir(), rtpGroupsock,
				  payloadFormatCode,
				  fSamplingFrequency,
				  "audio", mimeType,
				  fNumChannels);
}