mpeg3.cpp

网络MPEG4IP流媒体开发源代码

/*
 * 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. 2002.  All Rights Reserved.
 * 
 * Contributor(s): 
 *		Bill May ([e-mail])
 */

#include "mpeg4ip.h"
#include "mp4av.h"

//#define DEBUG_MPEG3_HINT 1

static double mpeg3_frame_rate_table[16] =
{
  0.0,   /* Pad */
  24000.0/1001.0,       /* Official frame rates */
  24.0,
  25.0,
  30000.0/1001.0,
  30.0,
  50.0,
  ((60.0*1000.0)/1001.0),
  60.0,

  1,                    /* Unofficial economy rates */
  5, 
  10,
  12,
  15,
  0,
  0,
};
#define MPEG3_START_CODE_PREFIX          0x000001
#define MPEG3_SEQUENCE_START_CODE        0x000001b3
#define MPEG3_PICTURE_START_CODE         0x00000100
#define MPEG3_GOP_START_CODE             0x000001b8
#define MPEG3_EXT_START_CODE             0x000001b5
#define MPEG3_SLICE_MIN_START            0x00000101
#define MPEG3_SLICE_MAX_START            0x000001af

#define SEQ_ID 1
extern "C" int MP4AV_Mpeg3ParseSeqHdr (uint8_t *pbuffer,
				       uint32_t buflen,
				       int *have_mpeg2,
				       uint32_t *height,
				       uint32_t *width,
				       double *frame_rate,
				       double *bitrate)
{
  uint32_t framerate_code;
  uint32_t bitrate_int;
  uint32_t bitrate_ext;
#if 1
  uint32_t scode, ix;
  int found = -1;
  *have_mpeg2 = 0;
  buflen -= 6;
  bitrate_int = 0;
  for (ix = 0; ix < buflen; ix++, pbuffer++) {
    scode = (pbuffer[0] << 24) | (pbuffer[1] << 16) | (pbuffer[2] << 8) | 
      pbuffer[3];

    if (scode == MPEG3_SEQUENCE_START_CODE) {
      pbuffer += sizeof(uint32_t);
      *width = (pbuffer[0]);
      *width <<= 4;
      *width |= ((pbuffer[1] >> 4) &0xf);
      *height = (pbuffer[1] & 0xf);
      *height <<= 8;
      *height |= pbuffer[2];
      framerate_code = pbuffer[3] & 0xf;
      *frame_rate = mpeg3_frame_rate_table[framerate_code];
      // 18 bits
      bitrate_int = (pbuffer[4] << 10) | 
	(pbuffer[5] << 2) | 
	((pbuffer[6] >> 6) & 0x3);
      *bitrate = bitrate_int;
      *bitrate *= 400.0;
      ix += sizeof(uint32_t) + 7;
      pbuffer += 7;
      found = 0;
    } else if (found == 0) {
      if (scode == MPEG3_EXT_START_CODE) {
	pbuffer += sizeof(uint32_t);
	ix += sizeof(uint32_t);
	switch ((pbuffer[0] >> 4) & 0xf) {
	case SEQ_ID:
	  *have_mpeg2 = 1;
	  *height = ((pbuffer[1] & 0x1) << 13) | 
	    ((pbuffer[2] & 0x80) << 5) |
	    (*height & 0x0fff);
	  *width = (((pbuffer[2] >> 5) & 0x3) << 12) | (*width & 0x0fff);
	  bitrate_ext = (pbuffer[2] & 0x1f) << 7;
	  bitrate_ext |= (pbuffer[3] >> 1) & 0x7f;
	  bitrate_int |= (bitrate_ext << 18);
	  *bitrate = bitrate_int;
	  *bitrate *= 400.0;
	  break;
	default:
	  break;
	}
	pbuffer++;
	ix++;
      } else if (scode == MPEG3_PICTURE_START_CODE) {
	return found;
      }
    }
  }
  return found;

#else
  // if you want to do the whole frame
  int ix;
  CBitstream bs(pbuffer, buflen);

  
  try {

    while (bs.PeekBits(32) != MPEG3_SEQUENCE_START_CODE) {
      bs.GetBits(8);
    }

    bs.GetBits(32); // start code

    *height = bs.GetBits(12);
    *width = bs.GetBits(12);
    bs.GetBits(4);
    framerate_code = bs.GetBits(4);
    *frame_rate = mpeg3_frame_rate_table[framerate_code];

    bs.GetBits(18); // bitrate
    bs.GetBits(1);  // marker bit
    bs.GetBits(10); // vbv buffer
    bs.GetBits(1); // constrained params
    if (bs.GetBits(1)) {  // intra_quantizer_matrix
      for (ix = 0; ix < 64; ix++) {
	bs.GetBits(8);
      }
    }
    if (bs.GetBits(1)) { // non_intra_quantizer_matrix
      for (ix = 0; ix < 64; ix++) {
	bs.GetBits(8);
      }
    }
  } catch (...) {
    return false;
  }
  return true;
#endif
}

extern "C" int MP4AV_Mpeg3PictHdrType (uint8_t *pbuffer)
{
  pbuffer += sizeof(uint32_t);
  return ((pbuffer[1] >> 3) & 0x7);
}

static int FindNextStart (uint8_t *pbuffer, 
			  uint32_t buflen,
			  uint32_t *optr, 
			  uint32_t *scode)
{
  uint32_t value;
  uint32_t offset;

  for (offset = 0; offset < buflen; offset++, pbuffer++) {
    value = (pbuffer[0] << 16) | (pbuffer[1] << 8) | (pbuffer[2] << 0); 

    if (value == MPEG3_START_CODE_PREFIX) {
      *optr = offset;
      *scode = (value << 8) | pbuffer[3];
      return 0;
    }
  }
  return -1;
}

static int FindNextSliceStart (uint8_t *pbuffer,
			       uint32_t startoffset, 
			       uint32_t buflen,
			       uint32_t *slice_offset)
{
  uint32_t slicestart, code;
  while (FindNextStart(pbuffer + startoffset, 
		       buflen - startoffset, 
		       &slicestart, 
		       &code) >= 0) {
#ifdef DEBUG_MPEG3_HINT
    printf("Code %x at offset %d\n", 
	   code, startoffset + slicestart);
#endif
    if ((code >= MPEG3_SLICE_MIN_START) &&
	(code <= MPEG3_SLICE_MAX_START)) {
      *slice_offset = slicestart + startoffset;
      return 0;
    }
    startoffset += slicestart + 4;
  }
  return -1;
}
				  
extern "C" int MP4AV_Mpeg3FindGopOrPictHdr (uint8_t *pbuffer,
					    uint32_t buflen,
					    int *frame_type)
{
  uint32_t value;
  uint32_t offset;
  int ftype;
  for (offset = 0; offset < buflen; offset++, pbuffer++) {
    value = (pbuffer[0] << 24) | (pbuffer[1] << 16) | (pbuffer[2] << 8) | 
      pbuffer[3];

    if (value == MPEG3_PICTURE_START_CODE) {
      ftype = MP4AV_Mpeg3PictHdrType(pbuffer);
      if (frame_type != NULL) *frame_type = ftype;
      if (ftype == 1) {
	return 0;
      } else {
	return -1;
      }
    } else if (value == MPEG3_GOP_START_CODE) {
      return 1;
    }
  }
  return -1;
}

extern "C" bool Mpeg12Hinter (MP4FileHandle mp4file,
			      MP4TrackId trackid,
			      uint16_t maxPayloadSize)
{
  uint32_t numSamples, maxSampleSize;
  uint8_t videoType;
  uint8_t rfc2250[4], rfc2250_2;
  uint32_t offset;
  uint32_t scode;
  int have_seq;
  bool stop;
  uint8_t *buffer, *pbuffer;
  uint8_t *pstart;
  uint8_t type;
  uint32_t next_slice, prev_slice;
  bool slice_at_begin;
  uint32_t sampleSize;
  MP4SampleId sid;

  MP4TrackId hintTrackId;

  numSamples = MP4GetTrackNumberOfSamples(mp4file, trackid);
  maxSampleSize = MP4GetTrackMaxSampleSize(mp4file, trackid);

  if (numSamples == 0) return false;

  videoType = MP4GetTrackVideoType(mp4file, trackid);

  if (videoType != MP4_MPEG1_VIDEO_TYPE &&
      videoType != MP4_MPEG2_VIDEO_TYPE) {
    return false;
  }

  hintTrackId = MP4AddHintTrack(mp4file, trackid);
  if (hintTrackId == MP4_INVALID_TRACK_ID) {
    return false;
  }

  uint8_t payload = 32;
  MP4SetHintTrackRtpPayload(mp4file, hintTrackId, "MPV", &payload, 0);


  buffer = (uint8_t *)malloc(maxSampleSize);
  if (buffer == NULL) {
    MP4DeleteTrack(mp4file, hintTrackId);
    return false;
  }

  maxPayloadSize -= 24; // this is for the 4 byte header

  for (sid = 1; sid <= numSamples; sid++) {
    sampleSize = maxSampleSize;
    MP4Timestamp startTime;
    MP4Duration duration;
    MP4Duration renderingOffset;
    bool isSyncSample;

    bool rc = MP4ReadSample(mp4file, trackid, sid,
			    &buffer, &sampleSize, 
			    &startTime, &duration, 
			    &renderingOffset, &isSyncSample);
#ifdef DEBUG_MPEG3_HINT
    printf("sid %d - sample size %d\n", sid, sampleSize);
#endif
    if (rc == false) {
      MP4DeleteTrack(mp4file, hintTrackId);
      return false;
    }

    // need to add rfc2250 header
    offset = 0;
    have_seq = 0;
    pbuffer = buffer;
    stop = false;
    do {
      uint32_t oldoffset;
      oldoffset = offset;
      if (FindNextStart(pbuffer + offset, 
			sampleSize - offset, 
			&offset, 
			&scode) < 0) {
	// didn't find the start code
#ifdef DEBUG_MPEG3_HINT
	printf("didn't find start code\n");
#endif
	stop = true;
      } else {
	offset += oldoffset;
#ifdef DEBUG_MPEG3_HINT
	printf("next sscode %x found at %d\n", scode, offset);
#endif
	if (scode == MPEG3_SEQUENCE_START_CODE) have_seq = 1;
	offset += 4; // start with next value
      }
    } while (scode != MPEG3_PICTURE_START_CODE && stop == false);
    
    pstart = pbuffer + offset; // point to inside of picture start
    type = (pstart[1] >> 3) & 0x7;

    rfc2250[0] = (*pstart >> 6) & 0x3;
    rfc2250[1] = (pstart[0] << 2) | ((pstart[1] >> 6) & 0x3); // temporal ref
    rfc2250[2] = type;
    if (have_seq != 0) {
      rfc2250[2] |= 0x20;
      have_seq = 0;
    }
    rfc2250_2 = rfc2250[2];

    rfc2250[3] = 0;
    if (type == 2 || type == 3) {
      rfc2250[3] = pstart[3] << 5;
      if ((pstart[4] & 0x80) != 0) rfc2250[3] |= 0x10;
      if (type == 3) {
	rfc2250[3] |= (pstart[4] >> 3) & 0xf;
      }
    }

    MP4AddRtpVideoHint(mp4file, hintTrackId, type == 3, renderingOffset);
    // Find the next slice.  Then we can add the header if the next
    // slice will be in the start.  This lets us set the S bit in 
    // rfc2250[2].  Then we need to loop to find the next slice that's
    // not in the buffer size - this should be in the while loop.
    
    prev_slice = 0;
    if (FindNextSliceStart(pbuffer, offset, sampleSize, &next_slice) < 0) {
      slice_at_begin = false;
    } else {
      slice_at_begin = true;
    }

#ifdef DEBUG_MPEG3_HINT
    printf("starting slice at %d\n", next_slice);
#endif
    offset = 0;
    bool nomoreslices = false;
    bool found_slice = slice_at_begin;
    bool onfirst = true;

    while (sampleSize > 0) {
      bool isLastPacket;
      uint32_t len_to_write;

      if (sampleSize <= maxPayloadSize) {
	// leave started_slice alone
	len_to_write = sampleSize;
	isLastPacket = true;
	prev_slice = 0;
      } else {
	found_slice =  (onfirst == false) && (nomoreslices == false) && (next_slice <= maxPayloadSize);
	onfirst = false;
	isLastPacket = false;

	while (nomoreslices == false && next_slice <= maxPayloadSize) {
	  prev_slice = next_slice;
	  if (FindNextSliceStart(pbuffer, next_slice + 4, sampleSize, &next_slice) >= 0) {
#ifdef DEBUG_MPEG3_HINT
	    printf("prev_slice %u next slice %u %u\n", prev_slice, next_slice,
		   offset + next_slice);
#endif
	    found_slice = true;
	  } else {
	    // at end
	    nomoreslices = true;
	  }
	}
	// prev_slice should have the end value.  If it's not 0, we have
	// the end of the slice.
	if (found_slice) len_to_write = prev_slice;
	else len_to_write = MIN(maxPayloadSize, sampleSize);
      } 

      rfc2250[2] = rfc2250_2;
      if (slice_at_begin) {
	rfc2250[2] |= 0x10; // set b bit
      }
      if (found_slice || isLastPacket) {
	rfc2250[2] |= 0x08; // set end of slice bit
	slice_at_begin = true; // for next time
      } else {
	slice_at_begin = false;
      }

#ifdef DEBUG_MPEG3_HINT
      printf("Adding packet, sid %u prev slice %u len_to_write %u\n",
	     sid, prev_slice, len_to_write);
      printf("Next slice %u offset %u %x %x %x %x\n\n", 
	     next_slice, offset, 
	     rfc2250[0], rfc2250[1], rfc2250[2], rfc2250[3]);
#endif

      // okay - we can now write out this packet.
      MP4AddRtpPacket(mp4file, hintTrackId, isLastPacket);
      // add the 4 byte header
      MP4AddRtpImmediateData(mp4file, hintTrackId, rfc2250, sizeof(rfc2250));

      // add the immediate data
      MP4AddRtpSampleData(mp4file, hintTrackId, sid, offset, len_to_write);
      offset += len_to_write;
      sampleSize -= len_to_write;
      prev_slice = 0;
      next_slice -= len_to_write;
      pbuffer += len_to_write;
    }
    MP4WriteRtpHint(mp4file, hintTrackId, duration, type == 1);
  }

  free(buffer);
  return true;
}