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/* layer.cpp
Created by SMF aka Antoine Laydier <laydier@usa.net>.
Minor modifications by Kai Vehmanen <k@eca.cx>.
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.
*/
/*=============================================================================
HEADERs
=============================================================================*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>
#include "layer.h"
/*=============================================================================
Class : Layers
=============================================================================*/
const int Layer::MPG_MD_STEREO = 0;
const int Layer::MPG_MD_JOINT_STEREO = 1;
const int Layer::MPG_MD_DUAL_CHANNEL = 2;
const int Layer::MPG_MD_MONO = 3;
const int Layer::MPG_MD_LR_LR = 0;
const int Layer::MPG_MD_LR_I = 1;
const int Layer::MPG_MD_MS_LR = 2;
const int Layer::MPG_MD_MS_I = 3;
const char *Layer::mode_names[5] = {"stereo", "j-stereo", "dual-ch",
"single-ch", "multi-ch"};
const char *Layer::layer_names[3] = {"I", "II", "III"};
const char *Layer::version_names[3] = {"MPEG-1", "MPEG-2 LSF", "MPEG-2.5"};
const char *Layer::version_nums[3] = {"1", "2", "2.5"};
const unsigned int Layer::bitrates[3][3][15] =
{
{
{0, 32, 64, 96, 128, 160, 192, 224, 256, 288, 320, 352, 384, 416, 448},
{0, 32, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384},
{0, 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320}
},
{
{0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256},
{0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160},
{0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160}
},
{
{0, 32, 48, 56, 64, 80, 96, 112, 128, 144, 160, 176, 192, 224, 256},
{0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160},
{0, 8, 16, 24, 32, 40, 48, 56, 64, 80, 96, 112, 128, 144, 160}
}
};
const unsigned int Layer::s_freq[3][4] =
{
{44100, 48000, 32000, 0},
{22050, 24000, 16000, 0},
{11025, 8000, 8000, 0}
};
const char * Layer::mode_name(void) { return (Layer::mode_names[mode_rep]); }
const char * Layer::layer_name(void) { return (Layer::layer_names[lay_rep - 1]); }
const char * Layer::version_name(void) { return (Layer::version_names[version_rep]); }
const char * Layer::version_num(void) { return (Layer::version_nums[version_rep]); }
int Layer::mode(void) { return(mode_rep); }
unsigned int Layer::bitrate(void)
{ return (Layer::bitrates[version_rep][lay_rep - 1][bitrate_index_rep]); }
unsigned int Layer::sfreq(void)
{ return (Layer::s_freq[version_rep][sampling_frequency_rep]); }
unsigned long Layer::length(void) { return bitrate() ? (fileSize_rep / (unsigned long)bitrate() /125) : 0; }
unsigned int Layer::pcmPerFrame(void) { return pcm_rep; }
bool Layer::get(const char* filename)
{
unsigned char *buff = new unsigned char[1024];
unsigned char *buffer;
size_t temp;
size_t readsize;
struct stat buf;
FILE *file;
// --
// 22.3.2000 - added the second parameter for getting
// around FILE* compatibility issues, k@eca.cx
stat(filename, &buf);
fileSize_rep = (unsigned long)buf.st_size;
/* Theoretically reading 1024 instead of just 4 means a performance hit
* if we transfer over net filesystems... However, no filesystem I know
* of uses block sizes under 1024 bytes.
*/
file = fopen(filename,"r");
if (!file) return(false);
fseek(file, 0, SEEK_SET);
readsize = fread(buff, 1, 1024, file);
fclose(file);
readsize -= 4;
if (readsize <= 0) {
delete[] buff;
return (false);
}
buffer = buff-1;
/* Scan through the block looking for a header */
do {
buffer++;
temp = ((buffer[0] << 4) & 0xFF0) | ((buffer[1] >> 4) & 0xE);
} while ((temp != 0xFFE) && ((size_t)(buffer-buff)<readsize));
if (temp != 0xFFE) {
delete[] buff;
return (false);
} else {
switch ((buffer[1] >> 3 & 0x3)) {
case 3:
version_rep = 0;
break;
case 2:
version_rep = 1;
break;
case 0:
version_rep = 2;
break;
default:
delete[] buff;
return (false);
}
lay_rep = 4 - ((buffer[1] >> 1) & 0x3);
error_protection_rep = !(buffer[1] & 0x1);
bitrate_index_rep = (buffer[2] >> 4) & 0x0F;
sampling_frequency_rep = (buffer[2] >> 2) & 0x3;
padding_rep = (buffer[2] >> 1) & 0x01;
extension_rep = buffer[2] & 0x01;
mode_rep = (buffer[3] >> 6) & 0x3;
mode_ext_rep = (buffer[3] >> 4) & 0x03;
copyright_rep = (buffer[3] >> 3) & 0x01;
original_rep = (buffer[3] >> 2) & 0x1;
emphasis_rep = (buffer[3]) & 0x3;
stereo_rep = (mode_rep == Layer::MPG_MD_MONO) ? 1 : 2;
// Added by Cp
pcm_rep = 32;
if (lay_rep == 3) {
pcm_rep *= 18;
if (version_rep == 0)
pcm_rep *= 2;
}
else{
pcm_rep *= 12;
if (lay_rep == 2)
pcm_rep *= 3;
}
delete[] buff;
return (true);
}
}
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