/**********
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 3 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)

This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
more details.

You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
**********/
// "liveMedia"
// Copyright (c) 1996-2020 Live Networks, Inc.  All rights reserved.
// A filter that breaks up a H.264 or H.265 Video Elementary Stream into NAL units.
// Implementation

#include "H264or5VideoStreamFramer.hh"
#include "MPEGVideoStreamParser.hh"
#include "BitVector.hh"
#include <GroupsockHelper.hh> // for "gettimeofday()"

////////// H264or5VideoStreamParser definition //////////

class H264or5VideoStreamParser: public MPEGVideoStreamParser {
public:
  H264or5VideoStreamParser(int hNumber, H264or5VideoStreamFramer* usingSource,
			   FramedSource* inputSource, Boolean includeStartCodeInOutput);
  virtual ~H264or5VideoStreamParser();

private: // redefined virtual functions:
  virtual void flushInput();
  virtual unsigned parse();

private:
  H264or5VideoStreamFramer* usingSource() {
    return (H264or5VideoStreamFramer*)fUsingSource;
  }

  Boolean isVPS(u_int8_t nal_unit_type) { return usingSource()->isVPS(nal_unit_type); }
  Boolean isSPS(u_int8_t nal_unit_type) { return usingSource()->isSPS(nal_unit_type); }
  Boolean isPPS(u_int8_t nal_unit_type) { return usingSource()->isPPS(nal_unit_type); }
  Boolean isVCL(u_int8_t nal_unit_type) { return usingSource()->isVCL(nal_unit_type); }
  Boolean isSEI(u_int8_t nal_unit_type);
  Boolean isEOF(u_int8_t nal_unit_type);
  Boolean usuallyBeginsAccessUnit(u_int8_t nal_unit_type);

  void removeEmulationBytes(u_int8_t* nalUnitCopy, unsigned maxSize, unsigned& nalUnitCopySize);

  void analyze_video_parameter_set_data(unsigned& num_units_in_tick, unsigned& time_scale);
  void analyze_seq_parameter_set_data(unsigned& num_units_in_tick, unsigned& time_scale);
  void profile_tier_level(BitVector& bv, unsigned max_sub_layers_minus1);
  void analyze_vui_parameters(BitVector& bv, unsigned& num_units_in_tick, unsigned& time_scale);
  void analyze_hrd_parameters(BitVector& bv);
  void analyze_sei_data(u_int8_t nal_unit_type);
  void analyze_sei_payload(unsigned payloadType, unsigned payloadSize, u_int8_t* payload);

private:
  int fHNumber; // 264 or 265
  unsigned fOutputStartCodeSize;
  Boolean fHaveSeenFirstStartCode, fHaveSeenFirstByteOfNALUnit;
  u_int8_t fFirstByteOfNALUnit;
  double fParsedFrameRate;
  // variables set & used in the specification:
  unsigned cpb_removal_delay_length_minus1, dpb_output_delay_length_minus1;
  Boolean CpbDpbDelaysPresentFlag, pic_struct_present_flag;
  double DeltaTfiDivisor;
};


////////// H264or5VideoStreamFramer implementation //////////

H264or5VideoStreamFramer
::H264or5VideoStreamFramer(int hNumber, UsageEnvironment& env, FramedSource* inputSource,
			   Boolean createParser,
			   Boolean includeStartCodeInOutput, Boolean insertAccessUnitDelimiters)
  : MPEGVideoStreamFramer(env, inputSource),
    fHNumber(hNumber), fIncludeStartCodeInOutput(includeStartCodeInOutput),
    fInsertAccessUnitDelimiters(insertAccessUnitDelimiters),
    fLastSeenVPS(NULL), fLastSeenVPSSize(0),
    fLastSeenSPS(NULL), fLastSeenSPSSize(0),
    fLastSeenPPS(NULL), fLastSeenPPSSize(0) {
  fParser = createParser
    ? new H264or5VideoStreamParser(hNumber, this, inputSource, includeStartCodeInOutput)
    : NULL;
  fFrameRate = 25.0; // We assume a frame rate of 25 fps, unless we learn otherwise (from parsing a VPS or SPS NAL unit)
}

H264or5VideoStreamFramer::~H264or5VideoStreamFramer() {
  delete[] fLastSeenPPS;
  delete[] fLastSeenSPS;
  delete[] fLastSeenVPS;
}

#define VPS_MAX_SIZE 1000 // larger than the largest possible VPS (Video Parameter Set) NAL unit

void H264or5VideoStreamFramer::saveCopyOfVPS(u_int8_t* from, unsigned size) {
  if (from == NULL) return;
  delete[] fLastSeenVPS;
  fLastSeenVPS = new u_int8_t[size];
  memmove(fLastSeenVPS, from, size);

  fLastSeenVPSSize = size;
}

#define SPS_MAX_SIZE 1000 // larger than the largest possible SPS (Sequence Parameter Set) NAL unit

void H264or5VideoStreamFramer::saveCopyOfSPS(u_int8_t* from, unsigned size) {
  if (from == NULL) return;
  delete[] fLastSeenSPS;
  fLastSeenSPS = new u_int8_t[size];
  memmove(fLastSeenSPS, from, size);

  fLastSeenSPSSize = size;
}

void H264or5VideoStreamFramer::saveCopyOfPPS(u_int8_t* from, unsigned size) {
  if (from == NULL) return;
  delete[] fLastSeenPPS;
  fLastSeenPPS = new u_int8_t[size];
  memmove(fLastSeenPPS, from, size);

  fLastSeenPPSSize = size;
}

void H264or5VideoStreamFramer::setPresentationTime() {
  if (fPresentationTimeBase.tv_sec == 0 && fPresentationTimeBase.tv_usec == 0) {
    // Set to the current time:
    gettimeofday(&fPresentationTimeBase, NULL);
    fNextPresentationTime = fPresentationTimeBase;
  }
  fPresentationTime = fNextPresentationTime;
}

Boolean H264or5VideoStreamFramer::isVPS(u_int8_t nal_unit_type) {
  // VPS NAL units occur in H.265 only:
  return fHNumber == 265 && nal_unit_type == 32;
}

Boolean H264or5VideoStreamFramer::isSPS(u_int8_t nal_unit_type) {
  return fHNumber == 264 ? nal_unit_type == 7 : nal_unit_type == 33;
}

Boolean H264or5VideoStreamFramer::isPPS(u_int8_t nal_unit_type) {
  return fHNumber == 264 ? nal_unit_type == 8 : nal_unit_type == 34;
}

Boolean H264or5VideoStreamFramer::isVCL(u_int8_t nal_unit_type) {
  return fHNumber == 264
    ? (nal_unit_type <= 5 && nal_unit_type > 0)
    : (nal_unit_type <= 31);
}

void H264or5VideoStreamFramer::doGetNextFrame() {
  if (fInsertAccessUnitDelimiters && pictureEndMarker()) {
    // Deliver an "access_unit_delimiter" NAL unit instead:
    unsigned const startCodeSize = fIncludeStartCodeInOutput ? 4: 0;
    unsigned const audNALSize = fHNumber == 264 ? 2 : 3;

    fFrameSize = startCodeSize + audNALSize;
    if (fFrameSize > fMaxSize) { // there's no space
      fNumTruncatedBytes = fFrameSize - fMaxSize;
      fFrameSize = fMaxSize;
      handleClosure();
      return;
    }

    if (fIncludeStartCodeInOutput) {
      *fTo++ = 0x00; *fTo++ = 0x00; *fTo++ = 0x00; *fTo++ = 0x01;
    }
    if (fHNumber == 264) {
      *fTo++ = 9; // "Access unit delimiter" nal_unit_type
      *fTo++ = 0xF0; // "primary_pic_type" (7); "rbsp_trailing_bits()"
    } else { // H.265
      *fTo++ = 35<<1; // "Access unit delimiter" nal_unit_type
      *fTo++ = 0; // "nuh_layer_id" (0); "nuh_temporal_id_plus1" (0) (Is this correct??)
      *fTo++ = 0x50; // "pic_type" (2); "rbsp_trailing_bits()" (Is this correct??)
    }

    pictureEndMarker() = False; // for next time
    afterGetting(this);
  } else {
    // Do the normal delivery of a NAL unit from the parser:
    MPEGVideoStreamFramer::doGetNextFrame();
  }
}


////////// H264or5VideoStreamParser implementation //////////

H264or5VideoStreamParser
::H264or5VideoStreamParser(int hNumber, H264or5VideoStreamFramer* usingSource,
			   FramedSource* inputSource, Boolean includeStartCodeInOutput)
  : MPEGVideoStreamParser(usingSource, inputSource),
    fHNumber(hNumber), fOutputStartCodeSize(includeStartCodeInOutput ? 4 : 0), fHaveSeenFirstStartCode(False), fHaveSeenFirstByteOfNALUnit(False), fParsedFrameRate(0.0),
    cpb_removal_delay_length_minus1(23), dpb_output_delay_length_minus1(23),
    CpbDpbDelaysPresentFlag(0), pic_struct_present_flag(0),
    DeltaTfiDivisor(2.0) {
}

H264or5VideoStreamParser::~H264or5VideoStreamParser() {
}

#define PREFIX_SEI_NUT 39 // for H.265
#define SUFFIX_SEI_NUT 40 // for H.265
Boolean H264or5VideoStreamParser::isSEI(u_int8_t nal_unit_type) {
  return fHNumber == 264
    ? nal_unit_type == 6
    : (nal_unit_type == PREFIX_SEI_NUT || nal_unit_type == SUFFIX_SEI_NUT);
}

Boolean H264or5VideoStreamParser::isEOF(u_int8_t nal_unit_type) {
  // "end of sequence" or "end of (bit)stream"
  return fHNumber == 264
    ? (nal_unit_type == 10 || nal_unit_type == 11)
    : (nal_unit_type == 36 || nal_unit_type == 37);
}

Boolean H264or5VideoStreamParser::usuallyBeginsAccessUnit(u_int8_t nal_unit_type) {
  return fHNumber == 264
    ? (nal_unit_type >= 6 && nal_unit_type <= 9) || (nal_unit_type >= 14 && nal_unit_type <= 18)
    : (nal_unit_type >= 32 && nal_unit_type <= 35) || (nal_unit_type == 39)
    || (nal_unit_type >= 41 && nal_unit_type <= 44)
    || (nal_unit_type >= 48 && nal_unit_type <= 55);
}

void H264or5VideoStreamParser
::removeEmulationBytes(u_int8_t* nalUnitCopy, unsigned maxSize, unsigned& nalUnitCopySize) {
  u_int8_t const* nalUnitOrig = fStartOfFrame + fOutputStartCodeSize;
  unsigned const numBytesInNALunit = fTo - nalUnitOrig;
  nalUnitCopySize
    = removeH264or5EmulationBytes(nalUnitCopy, maxSize, nalUnitOrig, numBytesInNALunit);
}

#ifdef DEBUG
char const* nal_unit_type_description_h264[32] = {
  "Unspecified", //0
  "Coded slice of a non-IDR picture", //1
  "Coded slice data partition A", //2
  "Coded slice data partition B", //3
  "Coded slice data partition C", //4
  "Coded slice of an IDR picture", //5
  "Supplemental enhancement information (SEI)", //6
  "Sequence parameter set", //7
  "Picture parameter set", //8
  "Access unit delimiter", //9
  "End of sequence", //10
  "End of stream", //11
  "Filler data", //12
  "Sequence parameter set extension", //13
  "Prefix NAL unit", //14
  "Subset sequence parameter set", //15
  "Reserved", //16
  "Reserved", //17
  "Reserved", //18
  "Coded slice of an auxiliary coded picture without partitioning", //19
  "Coded slice extension", //20
  "Reserved", //21
  "Reserved", //22
  "Reserved", //23
  "Unspecified", //24
  "Unspecified", //25
  "Unspecified", //26
  "Unspecified", //27
  "Unspecified", //28
  "Unspecified", //29
  "Unspecified", //30
  "Unspecified" //31
};
char const* nal_unit_type_description_h265[64] = {
  "Coded slice segment of a non-TSA, non-STSA trailing picture", //0
  "Coded slice segment of a non-TSA, non-STSA trailing picture", //1
  "Coded slice segment of a TSA picture", //2
  "Coded slice segment of a TSA picture", //3
  "Coded slice segment of a STSA picture", //4
  "Coded slice segment of a STSA picture", //5
  "Coded slice segment of a RADL picture", //6
  "Coded slice segment of a RADL picture", //7
  "Coded slice segment of a RASL picture", //8
  "Coded slice segment of a RASL picture", //9
  "Reserved", //10
  "Reserved", //11
  "Reserved", //12
  "Reserved", //13
  "Reserved", //14
  "Reserved", //15
  "Coded slice segment of a BLA picture", //16
  "Coded slice segment of a BLA picture", //17
  "Coded slice segment of a BLA picture", //18
  "Coded slice segment of an IDR picture", //19
  "Coded slice segment of an IDR picture", //20
  "Coded slice segment of a CRA picture", //21
  "Reserved", //22
  "Reserved", //23
  "Reserved", //24
  "Reserved", //25
  "Reserved", //26
  "Reserved", //27
  "Reserved", //28
  "Reserved", //29
  "Reserved", //30
  "Reserved", //31
  "Video parameter set", //32
  "Sequence parameter set", //33
  "Picture parameter set", //34
  "Access unit delimiter", //35
  "End of sequence", //36
  "End of bitstream", //37
  "Filler data", //38
  "Supplemental enhancement information (SEI)", //39
  "Supplemental enhancement information (SEI)", //40
  "Reserved", //41
  "Reserved", //42
  "Reserved", //43
  "Reserved", //44
  "Reserved", //45
  "Reserved", //46
  "Reserved", //47
  "Unspecified", //48
  "Unspecified", //49
  "Unspecified", //50
  "Unspecified", //51
  "Unspecified", //52
  "Unspecified", //53
  "Unspecified", //54
  "Unspecified", //55
  "Unspecified", //56
  "Unspecified", //57
  "Unspecified", //58
  "Unspecified", //59
  "Unspecified", //60
  "Unspecified", //61
  "Unspecified", //62
  "Unspecified", //63
};
#endif

#ifdef DEBUG
static unsigned numDebugTabs = 1;
#define DEBUG_PRINT_TABS for (unsigned _i = 0; _i < numDebugTabs; ++_i) fprintf(stderr, "\t")
#define DEBUG_PRINT(x) do { DEBUG_PRINT_TABS; fprintf(stderr, "%s: %d\n", #x, x); } while (0)
#define DEBUG_STR(x) do { DEBUG_PRINT_TABS; fprintf(stderr, "%s\n", x); } while (0)
class DebugTab {
public:
  DebugTab() {++numDebugTabs;}
  ~DebugTab() {--numDebugTabs;}
};
#define DEBUG_TAB DebugTab dummy
#else
#define DEBUG_PRINT(x) do {x = x;} while (0)
    // Note: the "x=x;" statement is intended to eliminate "unused variable" compiler warning messages
#define DEBUG_STR(x) do {} while (0)
#define DEBUG_TAB do {} while (0)
#endif

void H264or5VideoStreamParser::profile_tier_level(BitVector& bv, unsigned max_sub_layers_minus1) {
  bv.skipBits(96);

  unsigned i;
  Boolean sub_layer_profile_present_flag[7], sub_layer_level_present_flag[7];
  for (i = 0; i < max_sub_layers_minus1; ++i) {
    sub_layer_profile_present_flag[i] = bv.get1BitBoolean();
    sub_layer_level_present_flag[i] = bv.get1BitBoolean();
  }
  if (max_sub_layers_minus1 > 0) {
    bv.skipBits(2*(8-max_sub_layers_minus1)); // reserved_zero_2bits
  }
  for (i = 0; i < max_sub_layers_minus1; ++i) {
    if (sub_layer_profile_present_flag[i]) {
      bv.skipBits(88);
    }
    if (sub_layer_level_present_flag[i]) {
      bv.skipBits(8); // sub_layer_level_idc[i]
    }
  }
}

void H264or5VideoStreamParser
::analyze_vui_parameters(BitVector& bv,
			 unsigned& num_units_in_tick, unsigned& time_scale) {
  Boolean aspect_ratio_info_present_flag = bv.get1BitBoolean();
  DEBUG_PRINT(aspect_ratio_info_present_flag);
  if (aspect_ratio_info_present_flag) {
    DEBUG_TAB;
    unsigned aspect_ratio_idc = bv.getBits(8);
    DEBUG_PRINT(aspect_ratio_idc);
    if (aspect_ratio_idc == 255/*Extended_SAR*/) {
      bv.skipBits(32); // sar_width; sar_height
    }
  }
  Boolean overscan_info_present_flag = bv.get1BitBoolean();
  DEBUG_PRINT(overscan_info_present_flag);
  if (overscan_info_present_flag) {
    bv.skipBits(1); // overscan_appropriate_flag
  }
  Boolean video_signal_type_present_flag = bv.get1BitBoolean();
  DEBUG_PRINT(video_signal_type_present_flag);
  if (video_signal_type_present_flag) {
    DEBUG_TAB;
    bv.skipBits(4); // video_format; video_full_range_flag
    Boolean colour_description_present_flag = bv.get1BitBoolean();
    DEBUG_PRINT(colour_description_present_flag);
    if (colour_description_present_flag) {
      bv.skipBits(24); // colour_primaries; transfer_characteristics; matrix_coefficients
    }
  }
  Boolean chroma_loc_info_present_flag = bv.get1BitBoolean();
  DEBUG_PRINT(chroma_loc_info_present_flag);
  if (chroma_loc_info_present_flag) {
    (void)bv.get_expGolomb(); // chroma_sample_loc_type_top_field
    (void)bv.get_expGolomb(); // chroma_sample_loc_type_bottom_field
  }
  if (fHNumber == 265) {
    bv.skipBits(2); // neutral_chroma_indication_flag, field_seq_flag
    Boolean frame_field_info_present_flag = bv.get1BitBoolean();
    DEBUG_PRINT(frame_field_info_present_flag);
    pic_struct_present_flag = frame_field_info_present_flag; // hack to make H.265 like H.264
    Boolean default_display_window_flag = bv.get1BitBoolean();
    DEBUG_PRINT(default_display_window_flag);
    if (default_display_window_flag) {
      (void)bv.get_expGolomb(); // def_disp_win_left_offset
      (void)bv.get_expGolomb(); // def_disp_win_right_offset
      (void)bv.get_expGolomb(); // def_disp_win_top_offset
      (void)bv.get_expGolomb(); // def_disp_win_bottom_offset
    }
  }
  Boolean timing_info_present_flag = bv.get1BitBoolean();
  DEBUG_PRINT(timing_info_present_flag);
  if (timing_info_present_flag) {
    DEBUG_TAB;
    num_units_in_tick = bv.getBits(32);
    DEBUG_PRINT(num_units_in_tick);
    time_scale = bv.getBits(32);
    DEBUG_PRINT(time_scale);
    if (fHNumber == 264) {
      Boolean fixed_frame_rate_flag = bv.get1BitBoolean();
      DEBUG_PRINT(fixed_frame_rate_flag);
    } else { // 265
      Boolean vui_poc_proportional_to_timing_flag = bv.get1BitBoolean();
      DEBUG_PRINT(vui_poc_proportional_to_timing_flag);
      if (vui_poc_proportional_to_timing_flag) {
	unsigned vui_num_ticks_poc_diff_one_minus1 = bv.get_expGolomb();
	DEBUG_PRINT(vui_num_ticks_poc_diff_one_minus1);
      }
      return; // For H.265, don't bother parsing any more of this #####
    }
  }
  // The following is H.264 only: #####
  Boolean nal_hrd_parameters_present_flag = bv.get1BitBoolean();
  DEBUG_PRINT(nal_hrd_parameters_present_flag);
  if (nal_hrd_parameters_present_flag) analyze_hrd_parameters(bv);
  Boolean vcl_hrd_parameters_present_flag = bv.get1BitBoolean();
  DEBUG_PRINT(vcl_hrd_parameters_present_flag);
  if (vcl_hrd_parameters_present_flag) analyze_hrd_parameters(bv);
  CpbDpbDelaysPresentFlag = nal_hrd_parameters_present_flag || vcl_hrd_parameters_present_flag;
  if (CpbDpbDelaysPresentFlag) {
    bv.skipBits(1); // low_delay_hrd_flag
  }
  pic_struct_present_flag = bv.get1BitBoolean();
  DEBUG_PRINT(pic_struct_present_flag);
}

void H264or5VideoStreamParser::analyze_hrd_parameters(BitVector& bv) {
  DEBUG_TAB;
  unsigned cpb_cnt_minus1 = bv.get_expGolomb();
  DEBUG_PRINT(cpb_cnt_minus1);
  unsigned bit_rate_scale = bv.getBits(4);
  DEBUG_PRINT(bit_rate_scale);
  unsigned cpb_size_scale = bv.getBits(4);
  DEBUG_PRINT(cpb_size_scale);
  for (unsigned SchedSelIdx = 0; SchedSelIdx <= cpb_cnt_minus1; ++SchedSelIdx) {
    DEBUG_TAB;
    DEBUG_PRINT(SchedSelIdx);
    unsigned bit_rate_value_minus1 = bv.get_expGolomb();
    DEBUG_PRINT(bit_rate_value_minus1);
    unsigned cpb_size_value_minus1 = bv.get_expGolomb();
    DEBUG_PRINT(cpb_size_value_minus1);
    Boolean cbr_flag = bv.get1BitBoolean();
    DEBUG_PRINT(cbr_flag);
  }
  unsigned initial_cpb_removal_delay_length_minus1 = bv.getBits(5);
  DEBUG_PRINT(initial_cpb_removal_delay_length_minus1);
  cpb_removal_delay_length_minus1 = bv.getBits(5);
  DEBUG_PRINT(cpb_removal_delay_length_minus1);
  dpb_output_delay_length_minus1 = bv.getBits(5);
  DEBUG_PRINT(dpb_output_delay_length_minus1);
  unsigned time_offset_length = bv.getBits(5);
  DEBUG_PRINT(time_offset_length);
}

void H264or5VideoStreamParser
::analyze_video_parameter_set_data(unsigned& num_units_in_tick, unsigned& time_scale) {
  num_units_in_tick = time_scale = 0; // default values

  // Begin by making a copy of the NAL unit data, removing any 'emulation prevention' bytes:
  u_int8_t vps[VPS_MAX_SIZE];
  unsigned vpsSize;
  removeEmulationBytes(vps, sizeof vps, vpsSize);

  BitVector bv(vps, 0, 8*vpsSize);

  // Assert: fHNumber == 265 (because this function is called only when parsing H.265)
  unsigned i;

  bv.skipBits(28); // nal_unit_header, vps_video_parameter_set_id, vps_reserved_three_2bits, vps_max_layers_minus1
  unsigned vps_max_sub_layers_minus1 = bv.getBits(3);
  DEBUG_PRINT(vps_max_sub_layers_minus1);
  bv.skipBits(17); // vps_temporal_id_nesting_flag, vps_reserved_0xffff_16bits
  profile_tier_level(bv, vps_max_sub_layers_minus1);
  Boolean vps_sub_layer_ordering_info_present_flag = bv.get1BitBoolean();
  DEBUG_PRINT(vps_sub_layer_ordering_info_present_flag);
  for (i = vps_sub_layer_ordering_info_present_flag ? 0 : vps_max_sub_layers_minus1;
       i <= vps_max_sub_layers_minus1; ++i) {
    (void)bv.get_expGolomb(); // vps_max_dec_pic_buffering_minus1[i]
    (void)bv.get_expGolomb(); // vps_max_num_reorder_pics[i]
    (void)bv.get_expGolomb(); // vps_max_latency_increase_plus1[i]
  }    
  unsigned vps_max_layer_id = bv.getBits(6);
  DEBUG_PRINT(vps_max_layer_id);
  unsigned vps_num_layer_sets_minus1 = bv.get_expGolomb();
  DEBUG_PRINT(vps_num_layer_sets_minus1);
  for (i = 1; i <= vps_num_layer_sets_minus1; ++i) {
    bv.skipBits(vps_max_layer_id+1); // layer_id_included_flag[i][0..vps_max_layer_id]
  }
  Boolean vps_timing_info_present_flag = bv.get1BitBoolean();
  DEBUG_PRINT(vps_timing_info_present_flag);
  if (vps_timing_info_present_flag) {
    DEBUG_TAB;
    num_units_in_tick = bv.getBits(32);
    DEBUG_PRINT(num_units_in_tick);
    time_scale = bv.getBits(32);
    DEBUG_PRINT(time_scale);
    Boolean vps_poc_proportional_to_timing_flag = bv.get1BitBoolean();
    DEBUG_PRINT(vps_poc_proportional_to_timing_flag);
    if (vps_poc_proportional_to_timing_flag) {
      unsigned vps_num_ticks_poc_diff_one_minus1 = bv.get_expGolomb();
      DEBUG_PRINT(vps_num_ticks_poc_diff_one_minus1);
    }
  }
  Boolean vps_extension_flag = bv.get1BitBoolean();
  DEBUG_PRINT(vps_extension_flag);
}

void H264or5VideoStreamParser
::analyze_seq_parameter_set_data(unsigned& num_units_in_tick, unsigned& time_scale) {
  num_units_in_tick = time_scale = 0; // default values

  // Begin by making a copy of the NAL unit data, removing any 'emulation prevention' bytes:
  u_int8_t sps[SPS_MAX_SIZE];
  unsigned spsSize;
  removeEmulationBytes(sps, sizeof sps, spsSize);

  BitVector bv(sps, 0, 8*spsSize);

  if (fHNumber == 264) {
    bv.skipBits(8); // forbidden_zero_bit; nal_ref_idc; nal_unit_type
    unsigned profile_idc = bv.getBits(8);
    DEBUG_PRINT(profile_idc);
    unsigned constraint_setN_flag = bv.getBits(8); // also "reserved_zero_2bits" at end
    DEBUG_PRINT(constraint_setN_flag);
    unsigned level_idc = bv.getBits(8);
    DEBUG_PRINT(level_idc);
    unsigned seq_parameter_set_id = bv.get_expGolomb();
    DEBUG_PRINT(seq_parameter_set_id);
    if (profile_idc == 100 || profile_idc == 110 || profile_idc == 122 || profile_idc == 244 || profile_idc == 44 || profile_idc == 83 || profile_idc == 86 || profile_idc == 118 || profile_idc == 128 ) {
      DEBUG_TAB;
      unsigned chroma_format_idc = bv.get_expGolomb();
      DEBUG_PRINT(chroma_format_idc);
      if (chroma_format_idc == 3) {
	DEBUG_TAB;
	Boolean separate_colour_plane_flag = bv.get1BitBoolean();
	DEBUG_PRINT(separate_colour_plane_flag);
      }
      (void)bv.get_expGolomb(); // bit_depth_luma_minus8
      (void)bv.get_expGolomb(); // bit_depth_chroma_minus8
      bv.skipBits(1); // qpprime_y_zero_transform_bypass_flag
      Boolean seq_scaling_matrix_present_flag = bv.get1BitBoolean();
      DEBUG_PRINT(seq_scaling_matrix_present_flag);
      if (seq_scaling_matrix_present_flag) {
	for (int i = 0; i < ((chroma_format_idc != 3) ? 8 : 12); ++i) {
	  DEBUG_TAB;
	  DEBUG_PRINT(i);
	  Boolean seq_scaling_list_present_flag = bv.get1BitBoolean();
	  DEBUG_PRINT(seq_scaling_list_present_flag);
	  if (seq_scaling_list_present_flag) {
	    DEBUG_TAB;
	    unsigned sizeOfScalingList = i < 6 ? 16 : 64;
	    unsigned lastScale = 8;
	    unsigned nextScale = 8;
	    for (unsigned j = 0; j < sizeOfScalingList; ++j) {
	      DEBUG_TAB;
	      DEBUG_PRINT(j);
	      DEBUG_PRINT(nextScale);
	      if (nextScale != 0) {
		DEBUG_TAB;
		int delta_scale = bv.get_expGolombSigned();
		DEBUG_PRINT(delta_scale);
		nextScale = (lastScale + delta_scale + 256) % 256;
	      }
	      lastScale = (nextScale == 0) ? lastScale : nextScale;
	      DEBUG_PRINT(lastScale);
	    }
	  }
	}
      }
    }
    unsigned log2_max_frame_num_minus4 = bv.get_expGolomb();
    DEBUG_PRINT(log2_max_frame_num_minus4);
    unsigned pic_order_cnt_type = bv.get_expGolomb();
    DEBUG_PRINT(pic_order_cnt_type);
    if (pic_order_cnt_type == 0) {
      DEBUG_TAB;
      unsigned log2_max_pic_order_cnt_lsb_minus4 = bv.get_expGolomb();
      DEBUG_PRINT(log2_max_pic_order_cnt_lsb_minus4);
    } else if (pic_order_cnt_type == 1) {
      DEBUG_TAB;
      bv.skipBits(1); // delta_pic_order_always_zero_flag
      (void)bv.get_expGolombSigned(); // offset_for_non_ref_pic
      (void)bv.get_expGolombSigned(); // offset_for_top_to_bottom_field
      unsigned num_ref_frames_in_pic_order_cnt_cycle = bv.get_expGolomb();
      DEBUG_PRINT(num_ref_frames_in_pic_order_cnt_cycle);
      for (unsigned i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; ++i) {
	(void)bv.get_expGolombSigned(); // offset_for_ref_frame[i]
      }
    }
    unsigned max_num_ref_frames = bv.get_expGolomb();
    DEBUG_PRINT(max_num_ref_frames);
    Boolean gaps_in_frame_num_value_allowed_flag = bv.get1BitBoolean();
    DEBUG_PRINT(gaps_in_frame_num_value_allowed_flag);
    unsigned pic_width_in_mbs_minus1 = bv.get_expGolomb();
    DEBUG_PRINT(pic_width_in_mbs_minus1);
    unsigned pic_height_in_map_units_minus1 = bv.get_expGolomb();
    DEBUG_PRINT(pic_height_in_map_units_minus1);
    Boolean frame_mbs_only_flag = bv.get1BitBoolean();
    DEBUG_PRINT(frame_mbs_only_flag);
    if (!frame_mbs_only_flag) {
      bv.skipBits(1); // mb_adaptive_frame_field_flag
    }
    bv.skipBits(1); // direct_8x8_inference_flag
    Boolean frame_cropping_flag = bv.get1BitBoolean();
    DEBUG_PRINT(frame_cropping_flag);
    if (frame_cropping_flag) {
      (void)bv.get_expGolomb(); // frame_crop_left_offset
      (void)bv.get_expGolomb(); // frame_crop_right_offset
      (void)bv.get_expGolomb(); // frame_crop_top_offset
      (void)bv.get_expGolomb(); // frame_crop_bottom_offset
    }
    Boolean vui_parameters_present_flag = bv.get1BitBoolean();
    DEBUG_PRINT(vui_parameters_present_flag);
    if (vui_parameters_present_flag) {
      DEBUG_TAB;
      analyze_vui_parameters(bv, num_units_in_tick, time_scale);
    }
  } else { // 265
    unsigned i;

    bv.skipBits(16); // nal_unit_header
    bv.skipBits(4); // sps_video_parameter_set_id
    unsigned sps_max_sub_layers_minus1 = bv.getBits(3);
    DEBUG_PRINT(sps_max_sub_layers_minus1);
    bv.skipBits(1); // sps_temporal_id_nesting_flag
    profile_tier_level(bv, sps_max_sub_layers_minus1);
    (void)bv.get_expGolomb(); // sps_seq_parameter_set_id
    unsigned chroma_format_idc = bv.get_expGolomb();
    DEBUG_PRINT(chroma_format_idc);
    if (chroma_format_idc == 3) bv.skipBits(1); // separate_colour_plane_flag
    unsigned pic_width_in_luma_samples = bv.get_expGolomb();
    DEBUG_PRINT(pic_width_in_luma_samples);
    unsigned pic_height_in_luma_samples = bv.get_expGolomb();
    DEBUG_PRINT(pic_height_in_luma_samples);
    Boolean conformance_window_flag = bv.get1BitBoolean();
    DEBUG_PRINT(conformance_window_flag);
    if (conformance_window_flag) {
      DEBUG_TAB;
      unsigned conf_win_left_offset = bv.get_expGolomb();
      DEBUG_PRINT(conf_win_left_offset);
      unsigned conf_win_right_offset = bv.get_expGolomb();
      DEBUG_PRINT(conf_win_right_offset);
      unsigned conf_win_top_offset = bv.get_expGolomb();
      DEBUG_PRINT(conf_win_top_offset);
      unsigned conf_win_bottom_offset = bv.get_expGolomb();
      DEBUG_PRINT(conf_win_bottom_offset);
    }
    (void)bv.get_expGolomb(); // bit_depth_luma_minus8
    (void)bv.get_expGolomb(); // bit_depth_chroma_minus8
    unsigned log2_max_pic_order_cnt_lsb_minus4 = bv.get_expGolomb();
    Boolean sps_sub_layer_ordering_info_present_flag = bv.get1BitBoolean();
    DEBUG_PRINT(sps_sub_layer_ordering_info_present_flag);
    for (i = (sps_sub_layer_ordering_info_present_flag ? 0 : sps_max_sub_layers_minus1);
	 i <= sps_max_sub_layers_minus1; ++i) {
      (void)bv.get_expGolomb(); // sps_max_dec_pic_buffering_minus1[i]
      (void)bv.get_expGolomb(); // sps_max_num_reorder_pics[i]
      (void)bv.get_expGolomb(); // sps_max_latency_increase[i]
    }
    (void)bv.get_expGolomb(); // log2_min_luma_coding_block_size_minus3
    (void)bv.get_expGolomb(); // log2_diff_max_min_luma_coding_block_size
    (void)bv.get_expGolomb(); // log2_min_transform_block_size_minus2
    (void)bv.get_expGolomb(); // log2_diff_max_min_transform_block_size
    (void)bv.get_expGolomb(); // max_transform_hierarchy_depth_inter
    (void)bv.get_expGolomb(); // max_transform_hierarchy_depth_intra
    Boolean scaling_list_enabled_flag = bv.get1BitBoolean();
    DEBUG_PRINT(scaling_list_enabled_flag);
    if (scaling_list_enabled_flag) {
      DEBUG_TAB;
      Boolean sps_scaling_list_data_present_flag = bv.get1BitBoolean();
      DEBUG_PRINT(sps_scaling_list_data_present_flag);
      if (sps_scaling_list_data_present_flag) {
	// scaling_list_data()
	DEBUG_TAB;
	for (unsigned sizeId = 0; sizeId < 4; ++sizeId) {
	  DEBUG_PRINT(sizeId);
	  for (unsigned matrixId = 0; matrixId < (sizeId == 3 ? 2 : 6); ++matrixId) {
	    DEBUG_TAB;
	    DEBUG_PRINT(matrixId);
	    Boolean scaling_list_pred_mode_flag = bv.get1BitBoolean();
	    DEBUG_PRINT(scaling_list_pred_mode_flag);
	    if (!scaling_list_pred_mode_flag) {
	      (void)bv.get_expGolomb(); // scaling_list_pred_matrix_id_delta[sizeId][matrixId]
	    } else {
	      unsigned const c = 1 << (4+(sizeId<<1));
	      unsigned coefNum = c < 64 ? c : 64;
	      if (sizeId > 1) {
		(void)bv.get_expGolomb(); // scaling_list_dc_coef_minus8[sizeId][matrixId]
	      }
	      for (i = 0; i < coefNum; ++i) {
		(void)bv.get_expGolomb(); // scaling_list_delta_coef
	      }
	    }
	  } 
	}
      }
    }
    bv.skipBits(2); // amp_enabled_flag, sample_adaptive_offset_enabled_flag
    Boolean pcm_enabled_flag = bv.get1BitBoolean();
    DEBUG_PRINT(pcm_enabled_flag);
    if (pcm_enabled_flag) {
      bv.skipBits(8); // pcm_sample_bit_depth_luma_minus1, pcm_sample_bit_depth_chroma_minus1
      (void)bv.get_expGolomb(); // log2_min_pcm_luma_coding_block_size_minus3
      (void)bv.get_expGolomb(); // log2_diff_max_min_pcm_luma_coding_block_size
      bv.skipBits(1); // pcm_loop_filter_disabled_flag
    }
    unsigned num_short_term_ref_pic_sets = bv.get_expGolomb();
    DEBUG_PRINT(num_short_term_ref_pic_sets);
    unsigned num_negative_pics = 0, prev_num_negative_pics = 0;
    unsigned num_positive_pics = 0, prev_num_positive_pics = 0;
    for (i = 0; i < num_short_term_ref_pic_sets; ++i) {
      // short_term_ref_pic_set(i):
      DEBUG_TAB;
      DEBUG_PRINT(i);
      Boolean inter_ref_pic_set_prediction_flag = False;
      if (i != 0) {
	inter_ref_pic_set_prediction_flag = bv.get1BitBoolean();
      }
      DEBUG_PRINT(inter_ref_pic_set_prediction_flag);
      if (inter_ref_pic_set_prediction_flag) {
	DEBUG_TAB;
	if (i == num_short_term_ref_pic_sets) {
	  // This can't happen here, but it's in the spec, so we include it for completeness
	  (void)bv.get_expGolomb(); // delta_idx_minus1
	}
	bv.skipBits(1); // delta_rps_sign
	(void)bv.get_expGolomb(); // abs_delta_rps_minus1
	unsigned NumDeltaPocs = prev_num_negative_pics + prev_num_positive_pics; // correct???
	for (unsigned j = 0; j < NumDeltaPocs; ++j) {
	  DEBUG_PRINT(j);
	  Boolean used_by_curr_pic_flag = bv.get1BitBoolean();
	  DEBUG_PRINT(used_by_curr_pic_flag);
	  if (!used_by_curr_pic_flag) bv.skipBits(1); // use_delta_flag[j]
	}
      } else {
	prev_num_negative_pics = num_negative_pics;
	num_negative_pics = bv.get_expGolomb();
	DEBUG_PRINT(num_negative_pics);
	prev_num_positive_pics = num_positive_pics;
	num_positive_pics = bv.get_expGolomb();
	DEBUG_PRINT(num_positive_pics);
	unsigned k;
	for (k = 0; k < num_negative_pics; ++k) {
	  (void)bv.get_expGolomb(); // delta_poc_s0_minus1[k]
	  bv.skipBits(1); // used_by_curr_pic_s0_flag[k]
	}
	for (k = 0; k < num_positive_pics; ++k) {
	  (void)bv.get_expGolomb(); // delta_poc_s1_minus1[k]
	  bv.skipBits(1); // used_by_curr_pic_s1_flag[k]
	}
      }
    }
    Boolean long_term_ref_pics_present_flag = bv.get1BitBoolean();
    DEBUG_PRINT(long_term_ref_pics_present_flag);
    if (long_term_ref_pics_present_flag) {
      DEBUG_TAB;
      unsigned num_long_term_ref_pics_sps = bv.get_expGolomb();
      DEBUG_PRINT(num_long_term_ref_pics_sps);
      for (i = 0; i < num_long_term_ref_pics_sps; ++i) {
	bv.skipBits(log2_max_pic_order_cnt_lsb_minus4); // lt_ref_pic_poc_lsb_sps[i]
	bv.skipBits(1); // used_by_curr_pic_lt_sps_flag[1]
      }
    }
    bv.skipBits(2); // sps_temporal_mvp_enabled_flag, strong_intra_smoothing_enabled_flag
    Boolean vui_parameters_present_flag = bv.get1BitBoolean();
    DEBUG_PRINT(vui_parameters_present_flag);
    if (vui_parameters_present_flag) {
      DEBUG_TAB;
      analyze_vui_parameters(bv, num_units_in_tick, time_scale);
    }
    Boolean sps_extension_flag = bv.get1BitBoolean();
    DEBUG_PRINT(sps_extension_flag);
  }
}

#define SEI_MAX_SIZE 5000 // larger than the largest possible SEI NAL unit

#ifdef DEBUG
#define MAX_SEI_PAYLOAD_TYPE_DESCRIPTION_H264 46
char const* sei_payloadType_description_h264[MAX_SEI_PAYLOAD_TYPE_DESCRIPTION_H264+1] = {
  "buffering_period", //0
  "pic_timing", //1
  "pan_scan_rect", //2
  "filler_payload", //3
  "user_data_registered_itu_t_t35", //4
  "user_data_unregistered", //5
  "recovery_point", //6
  "dec_ref_pic_marking_repetition", //7
  "spare_pic", //8
  "scene_info", //9
  "sub_seq_info", //10
  "sub_seq_layer_characteristics", //11
  "sub_seq_characteristics", //12
  "full_frame_freeze", //13
  "full_frame_freeze_release", //14
  "full_frame_snapshot", //15
  "progressive_refinement_segment_start", //16
  "progressive_refinement_segment_end", //17
  "motion_constrained_slice_group_set", //18
  "film_grain_characteristics", //19
  "deblocking_filter_display_preference", //20
  "stereo_video_info", //21
  "post_filter_hint", //22
  "tone_mapping_info", //23
  "scalability_info", //24
  "sub_pic_scalable_layer", //25
  "non_required_layer_rep", //26
  "priority_layer_info", //27
  "layers_not_present", //28
  "layer_dependency_change", //29
  "scalable_nesting", //30
  "base_layer_temporal_hrd", //31
  "quality_layer_integrity_check", //32
  "redundant_pic_property", //33
  "tl0_dep_rep_index", //34
  "tl_switching_point", //35
  "parallel_decoding_info", //36
  "mvc_scalable_nesting", //37
  "view_scalability_info", //38
  "multiview_scene_info", //39
  "multiview_acquisition_info", //40
  "non_required_view_component", //41
  "view_dependency_change", //42
  "operation_points_not_present", //43
  "base_view_temporal_hrd", //44
  "frame_packing_arrangement", //45
  "reserved_sei_message" // 46 or higher
};
#endif

void H264or5VideoStreamParser::analyze_sei_data(u_int8_t nal_unit_type) {
  // Begin by making a copy of the NAL unit data, removing any 'emulation prevention' bytes:
  u_int8_t sei[SEI_MAX_SIZE];
  unsigned seiSize;
  removeEmulationBytes(sei, sizeof sei, seiSize);

  unsigned j = 1; // skip the initial byte (forbidden_zero_bit; nal_ref_idc; nal_unit_type); we've already seen it 
  while (j < seiSize) {
    unsigned payloadType = 0;
    do {
      payloadType += sei[j];
    } while (sei[j++] == 255 && j < seiSize);
    if (j >= seiSize) break;

    unsigned payloadSize = 0;
    do {
      payloadSize += sei[j];
    } while (sei[j++] == 255 && j < seiSize);
    if (j >= seiSize) break;

#ifdef DEBUG
    char const* description;
    if (fHNumber == 264) {
      unsigned descriptionNum = payloadType <= MAX_SEI_PAYLOAD_TYPE_DESCRIPTION_H264
	? payloadType : MAX_SEI_PAYLOAD_TYPE_DESCRIPTION_H264;
      description = sei_payloadType_description_h264[descriptionNum];
    } else { // 265
      description =
	payloadType == 3 ? "filler_payload" :
	payloadType == 4 ? "user_data_registered_itu_t_t35" :
	payloadType == 5 ? "user_data_unregistered" :
	payloadType == 17 ? "progressive_refinement_segment_end" :
	payloadType == 22 ? "post_filter_hint" :
	(payloadType == 132 && nal_unit_type == SUFFIX_SEI_NUT) ? "decoded_picture_hash" :
	nal_unit_type == SUFFIX_SEI_NUT ? "reserved_sei_message" :
	payloadType == 0 ? "buffering_period" :
	payloadType == 1 ? "pic_timing" :
	payloadType == 2 ? "pan_scan_rect" :
	payloadType == 6 ? "recovery_point" :
	payloadType == 9 ? "scene_info" :
	payloadType == 15 ? "picture_snapshot" :
	payloadType == 16 ? "progressive_refinement_segment_start" :
	payloadType == 19 ? "film_grain_characteristics" :
	payloadType == 23 ? "tone_mapping_info" :
	payloadType == 45 ? "frame_packing_arrangement" :
	payloadType == 47 ? "display_orientation" :
	payloadType == 128 ? "structure_of_pictures_info" :
	payloadType == 129 ? "active_parameter_sets" :
	payloadType == 130 ? "decoding_unit_info" :
	payloadType == 131 ? "temporal_sub_layer_zero_index" :
	payloadType == 133 ? "scalable_nesting" :
	payloadType == 134 ? "region_refresh_info" : "reserved_sei_message";
    }
    fprintf(stderr, "\tpayloadType %d (\"%s\"); payloadSize %d\n", payloadType, description, payloadSize);
#endif

    analyze_sei_payload(payloadType, payloadSize, &sei[j]);
    j += payloadSize;
  }
}

void H264or5VideoStreamParser
::analyze_sei_payload(unsigned payloadType, unsigned payloadSize, u_int8_t* payload) {
  if (payloadType == 1/* pic_timing, for both H.264 and H.265 */) {
    BitVector bv(payload, 0, 8*payloadSize);

    DEBUG_TAB;
    if (CpbDpbDelaysPresentFlag) {
      unsigned cpb_removal_delay = bv.getBits(cpb_removal_delay_length_minus1 + 1);
      DEBUG_PRINT(cpb_removal_delay);
      unsigned dpb_output_delay = bv.getBits(dpb_output_delay_length_minus1 + 1);
      DEBUG_PRINT(dpb_output_delay);
    }
    double prevDeltaTfiDivisor = DeltaTfiDivisor; 
    if (pic_struct_present_flag) {
      unsigned pic_struct = bv.getBits(4);
      DEBUG_PRINT(pic_struct);
      // Use this to set "DeltaTfiDivisor" (which is used to compute the frame rate):
      if (fHNumber == 264) {
	DeltaTfiDivisor =
	  pic_struct == 0 ? 2.0 :
	  pic_struct <= 2 ? 1.0 :
	  pic_struct <= 4 ? 2.0 :
	  pic_struct <= 6 ? 3.0 :
	  pic_struct == 7 ? 4.0 :
	  pic_struct == 8 ? 6.0 :
	  2.0;
      } else { // H.265
	DeltaTfiDivisor =
	  pic_struct == 0 ? 2.0 :
	  pic_struct <= 2 ? 1.0 :
	  pic_struct <= 4 ? 2.0 :
	  pic_struct <= 6 ? 3.0 :
	  pic_struct == 7 ? 2.0 :
	  pic_struct == 8 ? 3.0 :
	  pic_struct <= 12 ? 1.0 :
	  2.0;
      }
    } else {
      if (fHNumber == 264) {
	// Need to get field_pic_flag from slice_header to set this properly! #####
      } else { // H.265
	DeltaTfiDivisor = 1.0;
      }
    }
    // If "DeltaTfiDivisor" has changed, and we've already computed the frame rate, then
    // adjust it, based on the new value of "DeltaTfiDivisor":
    if (DeltaTfiDivisor != prevDeltaTfiDivisor && fParsedFrameRate != 0.0) {
      usingSource()->fFrameRate = fParsedFrameRate
	= fParsedFrameRate*(prevDeltaTfiDivisor/DeltaTfiDivisor);
#ifdef DEBUG
      fprintf(stderr, "Changed frame rate to %f fps\n", usingSource()->fFrameRate);
#endif
    }
    // Ignore the rest of the payload (timestamps) for now... #####
  }
}

void H264or5VideoStreamParser::flushInput() {
  fHaveSeenFirstStartCode = False;
  fHaveSeenFirstByteOfNALUnit = False;

  StreamParser::flushInput();
}

unsigned H264or5VideoStreamParser::parse() {
  try {
    // The stream must start with a 0x00000001:
    if (!fHaveSeenFirstStartCode) {
      // Skip over any input bytes that precede the first 0x00000001:
      u_int32_t first4Bytes;
      while ((first4Bytes = test4Bytes()) != 0x00000001) {
	get1Byte(); setParseState(); // ensures that we progress over bad data
      }
      skipBytes(4); // skip this initial code
      
      setParseState();
      fHaveSeenFirstStartCode = True; // from now on
    }
    
    if (fOutputStartCodeSize > 0 && curFrameSize() == 0 && !haveSeenEOF()) {
      // Include a start code in the output:
      save4Bytes(0x00000001);
    }

    // Then save everything up until the next 0x00000001 (4 bytes) or 0x000001 (3 bytes), or we hit EOF.
    // Also make note of the first byte, because it contains the "nal_unit_type": 
    if (haveSeenEOF()) {
      // We hit EOF the last time that we tried to parse this data, so we know that any remaining unparsed data
      // forms a complete NAL unit, and that there's no 'start code' at the end:
      unsigned remainingDataSize = totNumValidBytes() - curOffset();
#ifdef DEBUG
      unsigned const trailingNALUnitSize = remainingDataSize;
#endif
      while (remainingDataSize > 0) {
	u_int8_t nextByte = get1Byte();
	if (!fHaveSeenFirstByteOfNALUnit) {
	  fFirstByteOfNALUnit = nextByte;
	  fHaveSeenFirstByteOfNALUnit = True;
	}
	saveByte(nextByte);
	--remainingDataSize;
      }

#ifdef DEBUG
      if (fHNumber == 264) {
	u_int8_t nal_ref_idc = (fFirstByteOfNALUnit&0x60)>>5;
	u_int8_t nal_unit_type = fFirstByteOfNALUnit&0x1F;
	fprintf(stderr, "Parsed trailing %d-byte NAL-unit (nal_ref_idc: %d, nal_unit_type: %d (\"%s\"))\n",
		trailingNALUnitSize, nal_ref_idc, nal_unit_type, nal_unit_type_description_h264[nal_unit_type]);
      } else { // 265
	u_int8_t nal_unit_type = (fFirstByteOfNALUnit&0x7E)>>1;
	fprintf(stderr, "Parsed trailing %d-byte NAL-unit (nal_unit_type: %d (\"%s\"))\n",
		trailingNALUnitSize, nal_unit_type, nal_unit_type_description_h265[nal_unit_type]);
      }
#endif

      (void)get1Byte(); // forces another read, which will cause EOF to get handled for real this time
      return 0;
    } else {
      u_int32_t next4Bytes = test4Bytes();
      if (!fHaveSeenFirstByteOfNALUnit) {
	fFirstByteOfNALUnit = next4Bytes>>24;
	fHaveSeenFirstByteOfNALUnit = True;
      }
      while (next4Bytes != 0x00000001 && (next4Bytes&0xFFFFFF00) != 0x00000100) {
	// We save at least some of "next4Bytes".
	if ((unsigned)(next4Bytes&0xFF) > 1) {
	  // Common case: 0x00000001 or 0x000001 definitely doesn't begin anywhere in "next4Bytes", so we save all of it:
	  save4Bytes(next4Bytes);
	  skipBytes(4);
	} else {
	  // Save the first byte, and continue testing the rest:
	  saveByte(next4Bytes>>24);
	  skipBytes(1);
	}
	setParseState(); // ensures forward progress
	next4Bytes = test4Bytes();
      }
      // Assert: next4Bytes starts with 0x00000001 or 0x000001, and we've saved all previous bytes (forming a complete NAL unit).
      // Skip over these remaining bytes, up until the start of the next NAL unit:
      if (next4Bytes == 0x00000001) {
	skipBytes(4);
      } else {
	skipBytes(3);
      }
    }

    fHaveSeenFirstByteOfNALUnit = False; // for the next NAL unit that we'll parse
    u_int8_t nal_unit_type;
    if (fHNumber == 264) {
      nal_unit_type = fFirstByteOfNALUnit&0x1F;
#ifdef DEBUG
      u_int8_t nal_ref_idc = (fFirstByteOfNALUnit&0x60)>>5;
      fprintf(stderr, "Parsed %d-byte NAL-unit (nal_ref_idc: %d, nal_unit_type: %d (\"%s\"))\n",
	      curFrameSize()-fOutputStartCodeSize, nal_ref_idc, nal_unit_type, nal_unit_type_description_h264[nal_unit_type]);
#endif
    } else { // 265
      nal_unit_type = (fFirstByteOfNALUnit&0x7E)>>1;
#ifdef DEBUG
      fprintf(stderr, "Parsed %d-byte NAL-unit (nal_unit_type: %d (\"%s\"))\n",
	      curFrameSize()-fOutputStartCodeSize, nal_unit_type, nal_unit_type_description_h265[nal_unit_type]);
#endif
    }

    // Now that we have found (& copied) a NAL unit, process it if it's of special interest to us:
    if (isVPS(nal_unit_type)) { // Video parameter set
      // First, save a copy of this NAL unit, in case the downstream object wants to see it:
      usingSource()->saveCopyOfVPS(fStartOfFrame + fOutputStartCodeSize, curFrameSize() - fOutputStartCodeSize);

      if (fParsedFrameRate == 0.0) {
	// We haven't yet parsed a frame rate from the stream.
	// So parse this NAL unit to check whether frame rate information is present:
	unsigned num_units_in_tick, time_scale;
	analyze_video_parameter_set_data(num_units_in_tick, time_scale);
	if (time_scale > 0 && num_units_in_tick > 0) {
	  usingSource()->fFrameRate = fParsedFrameRate
	    = time_scale/(DeltaTfiDivisor*num_units_in_tick);
#ifdef DEBUG
	  fprintf(stderr, "Set frame rate to %f fps\n", usingSource()->fFrameRate);
#endif
	} else {
#ifdef DEBUG
	  fprintf(stderr, "\tThis \"Video Parameter Set\" NAL unit contained no frame rate information, so we use a default frame rate of %f fps\n", usingSource()->fFrameRate);
#endif
	}
      }
    } else if (isSPS(nal_unit_type)) { // Sequence parameter set
      // First, save a copy of this NAL unit, in case the downstream object wants to see it:
      usingSource()->saveCopyOfSPS(fStartOfFrame + fOutputStartCodeSize, curFrameSize() - fOutputStartCodeSize);

      if (fParsedFrameRate == 0.0) {
	// We haven't yet parsed a frame rate from the stream.
	// So parse this NAL unit to check whether frame rate information is present:
	unsigned num_units_in_tick, time_scale;
	analyze_seq_parameter_set_data(num_units_in_tick, time_scale);
	if (time_scale > 0 && num_units_in_tick > 0) {
	  usingSource()->fFrameRate = fParsedFrameRate
	    = time_scale/(DeltaTfiDivisor*num_units_in_tick);
#ifdef DEBUG
	  fprintf(stderr, "Set frame rate to %f fps\n", usingSource()->fFrameRate);
#endif
	} else {
#ifdef DEBUG
	  fprintf(stderr, "\tThis \"Sequence Parameter Set\" NAL unit contained no frame rate information, so we use a default frame rate of %f fps\n", usingSource()->fFrameRate);
#endif
	}
      }
    } else if (isPPS(nal_unit_type)) { // Picture parameter set
      // Save a copy of this NAL unit, in case the downstream object wants to see it:
      usingSource()->saveCopyOfPPS(fStartOfFrame + fOutputStartCodeSize, curFrameSize() - fOutputStartCodeSize);
    } else if (isSEI(nal_unit_type)) { // Supplemental enhancement information (SEI)
      analyze_sei_data(nal_unit_type);
      // Later, perhaps adjust "fPresentationTime" if we saw a "pic_timing" SEI payload??? #####
    }

    usingSource()->setPresentationTime();
#ifdef DEBUG
    unsigned long secs = (unsigned long)usingSource()->fPresentationTime.tv_sec;
    unsigned uSecs = (unsigned)usingSource()->fPresentationTime.tv_usec;
    fprintf(stderr, "\tPresentation time: %lu.%06u\n", secs, uSecs);
#endif

    // Now, check whether this NAL unit ends an 'access unit'.
    // (RTP streamers need to know this in order to figure out whether or not to set the "M" bit.)
    Boolean thisNALUnitEndsAccessUnit;
    if (haveSeenEOF() || isEOF(nal_unit_type)) {
      // There is no next NAL unit, so we assume that this one ends the current 'access unit':
      thisNALUnitEndsAccessUnit = True;
    } else if (usuallyBeginsAccessUnit(nal_unit_type)) {
      // These NAL units usually *begin* an access unit, so assume that they don't end one here:
      thisNALUnitEndsAccessUnit = False;
    } else {
      // We need to check the *next* NAL unit to figure out whether
      // the current NAL unit ends an 'access unit':
      u_int8_t firstBytesOfNextNALUnit[3];
      testBytes(firstBytesOfNextNALUnit, 3);

      u_int8_t const& next_nal_unit_type = fHNumber == 264
	? (firstBytesOfNextNALUnit[0]&0x1F) : ((firstBytesOfNextNALUnit[0]&0x7E)>>1);
      if (isVCL(next_nal_unit_type)) {
	// The high-order bit of the byte after the "nal_unit_header" tells us whether it's
	// the start of a new 'access unit' (and thus the current NAL unit ends an 'access unit'):
	u_int8_t const byteAfter_nal_unit_header
	  = fHNumber == 264 ? firstBytesOfNextNALUnit[1] : firstBytesOfNextNALUnit[2];
	thisNALUnitEndsAccessUnit = (byteAfter_nal_unit_header&0x80) != 0;
      } else if (usuallyBeginsAccessUnit(next_nal_unit_type)) {
	// The next NAL unit's type is one that usually appears at the start of an 'access unit',
	// so we assume that the current NAL unit ends an 'access unit':
	thisNALUnitEndsAccessUnit = True;
      } else {
	// The next NAL unit definitely doesn't start a new 'access unit',
	// which means that the current NAL unit doesn't end one:
	thisNALUnitEndsAccessUnit = False;
      }
    }
	
    if (thisNALUnitEndsAccessUnit) {
#ifdef DEBUG
      fprintf(stderr, "*****This NAL unit ends the current access unit*****\n");
#endif
      usingSource()->fPictureEndMarker = True;
      ++usingSource()->fPictureCount;

      // Note that the presentation time for the next NAL unit will be different:
      struct timeval& nextPT = usingSource()->fNextPresentationTime; // alias
      nextPT = usingSource()->fPresentationTime;
      double nextFraction = nextPT.tv_usec/1000000.0 + 1/usingSource()->fFrameRate;
      unsigned nextSecsIncrement = (long)nextFraction;
      nextPT.tv_sec += (long)nextSecsIncrement;
      nextPT.tv_usec = (long)((nextFraction - nextSecsIncrement)*1000000);
    }
    setParseState();

    return curFrameSize();
  } catch (int /*e*/) {
#ifdef DEBUG
    fprintf(stderr, "H264or5VideoStreamParser::parse() EXCEPTION (This is normal behavior - *not* an error)\n");
#endif
    return 0;  // the parsing got interrupted
  }
}

unsigned removeH264or5EmulationBytes(u_int8_t* to, unsigned toMaxSize,
                                     u_int8_t const* from, unsigned fromSize) {
  unsigned toSize = 0;
  unsigned i = 0;
  while (i < fromSize && toSize+1 < toMaxSize) {
    if (i+2 < fromSize && from[i] == 0 && from[i+1] == 0 && from[i+2] == 3) {
      to[toSize] = to[toSize+1] = 0;
      toSize += 2;
      i += 3;
    } else {
      to[toSize] = from[i];
      toSize += 1;
      i += 1;
    }
  }

  return toSize;
}