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/*C
(c) 2005 bl0rg.net
**/
#include "conf.h"
#include <assert.h>
#include <stdlib.h>
#include "mp3.h"
/*M
\emph{Bitrate table for MPEG Audio Layer III version 1.0.}
Free format MP3s are considered invalid (for now).
**/
unsigned long bitratetable[16] = {
-1, 32, 40, 48, 56, 64, 80, 96,112,128,160,192,224,256,320, -1
};
/*M
\emph{Samplerate table for MPEG Audio Layer III version 1.0.}
**/
unsigned short sampleratetable[4] = {
44100, 48000, 32000, -1
};
/*M
\emph{Calculate various information about the MP3 frame.}
\verb|frame size| and \verb|frame data size| are given in
bytes. \verb|frame data size| is the size of the MP3 frame without
header and without side information.
**/
void mp3_calc_hdr(mp3_frame_t *frame) {
assert(frame != NULL);
frame->bitrate = bitratetable[frame->bitrate_index];
frame->samplerate = sampleratetable[frame->samplerfindex];
frame->samplelen = 1152; /* only layer III */
frame->si_size = frame->mode != (unsigned char)3 ? 32 : 17;
frame->si_bitsize = frame->si_size * 8;
/* calculate frame length */
frame->frame_size = 144000 * frame->bitrate;
frame->frame_size /= frame->samplerate;
frame->frame_size += frame->padding_bit;
frame->frame_data_size = frame->frame_size - 4 - frame->si_size;
if (frame->protected == 0)
frame->frame_data_size -= 2;
frame->usec = (double)frame->frame_size * 8 * 1000.0 / ((double)frame->bitrate);
}
unsigned long mp3_frame_size(mp3_frame_t *frame) {
return MP3_HDR_SIZE + frame->si_size + frame->adu_size + (frame->protected ? 0 : 2);
}
/*M
**/
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