www.pudn.com > XvidQP.rar > header.h

/* header.h 
 
	Declarations for MPEG header class 
 
	A few layer III, MPEG-2 LSF, and seeking modifications made by Jeff Tsay. 
 
   Last modified : 04/19/97 */ 
 
/* 
 *  @(#) header.h 1.7, last edit: 6/15/94 16:55:33 
 *  @(#) Copyright (C) 1993, 1994 Tobias Bading (bading@cs.tu-berlin.de) 
 *  @(#) Berlin University of Technology 
 * 
 *  This program is free software; you can redistribute it and/or modify 
 *  it under the terms of the GNU General Public License as published by 
 *  the Free Software Foundation; either version 2 of the License, or 
 *  (at your option) any later version. 
 * 
 *  This program 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 General Public License for more details. 
 * 
 *  You should have received a copy of the GNU General Public License 
 *  along with this program; if not, write to the Free Software 
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 
 */ 
 
#ifndef HEADER_H 
#define HEADER_H 
 
#include "all.h" 
#include "ibitstr.h" 
#include "crc.h" 
 
enum e_version { MPEG2_LSF, MPEG1 }; 
enum e_mode { stereo, joint_stereo, dual_channel, single_channel }; 
enum e_sample_frequency { fourtyfour_point_one, fourtyeight, thirtytwo }; 
 
// Class for extraction information from a frame header: 
class Header 
{ 
 
private: 
 
  static const uint32	frequencies[2][4]; 
  uint32		h_layer, h_protection_bit, h_bitrate_index, 
				h_padding_bit, h_mode_extension; 
  e_version h_version; 
  e_mode		h_mode; 
  e_sample_frequency	h_sample_frequency; 
  uint32		h_number_of_subbands, h_intensity_stereo_bound; 
  bool		h_copyright, h_original; 
  bool      initial_sync; 
  Crc16		*crc; 
  uint32    *offset; 
  uint16		checksum; 
  uint32    framesize; 
  uint32    nSlots; 
 
public: 
 
  Header(); 
  Header(const Header &h0); 
 
  ~Header(); 
 
  Header& operator = (const Header &h0); 
 
  bool read_header(Ibitstream *stream, Crc16 **crc); 
  // read a 32-bit header from the bitstream 
 
  // functions to query header contents: 
  e_version version()		 const { return h_version; } 
  uint32		layer()         const { return h_layer; } 
  uint32		bitrate_index() const { return h_bitrate_index; } 
 
  e_sample_frequency	sample_frequency() const 
  { 
     return h_sample_frequency; 
  } 
 
  uint32		frequency() const 
  { 
     return frequencies[h_version][h_sample_frequency]; 
  } 
 
  e_mode		mode()         const { return h_mode; } 
  bool		checksums()    const { return (bool) !h_protection_bit; } 
  bool		copyright()    const { return h_copyright; } 
  bool		original()     const { return h_original; } 
 
  bool		checksum_ok () const { return (bool) (checksum == crc->checksum ()); } 
			// compares computed checksum with stream checksum 
 
  // Seeking and layer III stuff 
  bool      padding()        const { return (bool) h_padding_bit; } 
  uint32    slots()          const { return nSlots; } 
  uint32		mode_extension() const { return h_mode_extension; } 
  uint32		calculate_framesize(); // made public 
 
  // functions which return header informations as strings: 
  const char *	layer_string() const; 
  const char *	bitrate_string() const; 
  const char *	sample_frequency_string() const; 
  const char *	mode_string() const; 
  const char * version_string() const; 
 
  uint32		number_of_subbands() const 
  // returns the number of subbands in the current frame 
  { 
     return h_number_of_subbands; 
  } 
 
  uint32		intensity_stereo_bound() const 
  // (Layer II joint stereo only) 
  // returns the number of subbands which are in stereo mode, 
  // subbands above that limit are in intensity stereo mode 
  { 
     return h_intensity_stereo_bound; 
  } 
 
  // Scrolling stuff 
 
#ifdef SEEK_STOP 
  bool      stream_seek(Ibitstream *stream, uint32 seek_pos); 
#endif // SEEK_STOP 
 
  uint32    max_number_of_frames(Ibitstream *stream) const; 
  uint32    min_number_of_frames(Ibitstream *stream) const; 
 
  real      ms_per_frame() const; 
  				// milliseconds per frame, for time display 
 
  real      total_ms(Ibitstream *stream) const; 
 
}; 
 
#endif