rfc2250.cpp

完整的RTP RTSP代码库

/*
 * The contents of this file are subject to the Mozilla Public
 * License Version 1.1 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of
 * the License at http://www.mozilla.org/MPL/
 * 
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 * 
 * The Original Code is MPEG4IP.
 * 
 * The Initial Developer of the Original Code is Cisco Systems Inc.
 * Portions created by Cisco Systems Inc. are
 * Copyright (C) Cisco Systems Inc. 2000-2002.  All Rights Reserved.
 * 
 * Contributor(s): 
 *		Dave Mackie		[e-mail]
 */

/* 
 * Notes:
 *  - file formatted with tabstops == 4 spaces 
 */

#include <mp4av_common.h>

extern "C" bool MP4AV_Rfc2250Hinter(
				    MP4FileHandle mp4File, 
				    MP4TrackId mediaTrackId, 
				    bool interleave,
				    u_int16_t maxPayloadSize)
{
  // RFC 2250 doesn't support interleaving
  if (interleave) {
    return false;
  }

  u_int32_t numSamples =
    MP4GetTrackNumberOfSamples(mp4File, mediaTrackId);

  if (numSamples == 0) {
    return false;
  }

  u_int8_t audioType =
    MP4GetTrackEsdsObjectTypeId(mp4File, mediaTrackId);

  if (!MP4_IS_MP3_AUDIO_TYPE(audioType)) {
    return false;
  }

  MP4Duration sampleDuration = 
    MP4AV_GetAudioSampleDuration(mp4File, mediaTrackId);

  if (sampleDuration == MP4_INVALID_DURATION) {
    return false;
  }

  MP4TrackId hintTrackId =
    MP4AddHintTrack(mp4File, mediaTrackId);

  if (hintTrackId == MP4_INVALID_TRACK_ID) {
    return false;
  }

  u_int8_t payloadNumber = MP4_SET_DYNAMIC_PAYLOAD; 
  // use dynamic payload number

  if (MP4GetTrackTimeScale(mp4File, mediaTrackId) == 90000) {
    payloadNumber = 14;
  }
	
  if (MP4SetHintTrackRtpPayload(mp4File, hintTrackId, 
				"MPA", &payloadNumber, 0) == false) 
    return false;

  u_int16_t bytesThisHint = 0;
  u_int16_t samplesThisHint = 0;

  if (MP4AddRtpHint(mp4File, hintTrackId) == false ||
      MP4AddRtpPacket(mp4File, hintTrackId, true) == false) 
    return false;

  for (MP4SampleId sampleId = 1; sampleId <= numSamples; sampleId++) {
    u_int32_t sampleSize = 
      MP4GetSampleSize(mp4File, mediaTrackId, sampleId);

    if (samplesThisHint > 0) {
      if (bytesThisHint + sampleSize <= maxPayloadSize) {
	// add the mp3 frame to current hint
	if (MP4AddRtpSampleData(mp4File, hintTrackId,
				sampleId, 0, sampleSize) == false)
	  return false;

	samplesThisHint++;
	bytesThisHint += sampleSize;
	continue;
      } else {
	// write out current hint
	if (MP4WriteRtpHint(mp4File, hintTrackId, 
			    samplesThisHint * sampleDuration) == false ||
	    MP4AddRtpHint(mp4File, hintTrackId) == false ||
	    MP4AddRtpPacket(mp4File, hintTrackId, true) == false) 
	  return false;

	// start a new hint 
	samplesThisHint = 0;
	bytesThisHint = 0;


	// fall thru
      }
    }

    if (sampleSize + 4 <= maxPayloadSize) {
      // add rfc 2250 payload header
      static u_int32_t zero32 = 0;

      if (MP4AddRtpImmediateData(mp4File, hintTrackId,
				 (u_int8_t*)&zero32, 
				 sizeof(zero32)) == false ||
	  // add the mp3 frame to current hint
	  MP4AddRtpSampleData(mp4File, hintTrackId,
			      sampleId, 0, sampleSize) == false) return false;

      bytesThisHint += (4 + sampleSize);
    } else {
      // jumbo frame, need to fragment it
      u_int16_t sampleOffset = 0;

      while (sampleOffset < sampleSize) {
	u_int16_t fragLength = 
	  MIN(sampleSize - sampleOffset, maxPayloadSize) - 4;

	u_int8_t payloadHeader[4];
	payloadHeader[0] = payloadHeader[1] = 0;
	payloadHeader[2] = (sampleOffset >> 8);
	payloadHeader[3] = sampleOffset & 0xFF;

	if (MP4AddRtpImmediateData(mp4File, hintTrackId,
				   (u_int8_t*)&payloadHeader, 
				   sizeof(payloadHeader)) == false ||
	    MP4AddRtpSampleData(mp4File, hintTrackId,
				sampleId, sampleOffset, 
				fragLength) == false) return false;

	sampleOffset += fragLength;

	// if we're not at the last fragment
	if (sampleOffset < sampleSize) {
	  if (MP4AddRtpPacket(mp4File, hintTrackId, false) == false) 
	    return false;
	}
      }

      // lie to ourselves so as to force next frame to output 
      // our hint as is, and start a new hint for itself
      bytesThisHint = maxPayloadSize;
    }

    samplesThisHint = 1;
  }

  // write out current (final) hint
  if (MP4WriteRtpHint(mp4File, hintTrackId, 
		      samplesThisHint * sampleDuration) == false)
    return false;

  return true;
}