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/*
* decode_mp3.c
*
* Copyright (C) Thomas Oestreich - June 2001
*
* This file is part of transcode, a video stream processing tool
*
* transcode 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, or (at your option)
* any later version.
*
* transcode 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 GNU Make; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#include <stdint.h>
#include "transcode.h"
#include "libtc/libtc.h"
#include "tcinfo.h"
#include "ioaux.h"
#include "tc.h"
#ifdef HAVE_LAME
#include "mpg123.h"
#define MP3_PCM_SIZE 1152
static uint16_t buffer[MP3_PCM_SIZE<<2];
static uint16_t ch1[MP3_PCM_SIZE], ch2[MP3_PCM_SIZE];
#endif // HAVE_LAME
#define MP3_AUDIO_ID 0x55
#define MP2_AUDIO_ID 0x50
/*
* About MP2/3 handling differences:
* It is possible that lame_decode_initfile() when looking for an MP3 syncbyte
* finds an invalid one (esp. in broken mp3 streams). Thats why we use the
* format argument to decide which syncword detection is to be done. The
* syncword detection for mp2 also finds mp3 sync bytes but NOT the other way round.
*/
/* ------------------------------------------------------------
*
* decoder thread
*
* ------------------------------------------------------------*/
static void decode_mpaudio(decode_t *decode, int format)
{
#ifdef HAVE_LAME
int samples = 0, j, bytes, channels = 0, i, padding = 0;
int verbose;
mp3data_struct *mp3data = NULL;
FILE *in_file = NULL;
if (format != MP2_AUDIO_ID && format != MP3_AUDIO_ID) {
tc_log_error(__FILE__, "wrong mpeg audio format: 0x%x", format);
exit(1);
}
verbose = decode->verbose;
// init decoder
mp3data = tc_zalloc(sizeof(mp3data_struct));
if (mp3data == NULL) {
tc_log_error(__FILE__, "out of memory");
exit(1);
}
if (lame_decode_init() < 0) {
tc_log_error(__FILE__, "failed to init decoder");
exit(1);
}
in_file = fdopen(decode->fd_in, "r");
if (format == MP3_AUDIO_ID) {
int c = 0;
/* padding detection */
while (!(c = fgetc(in_file)))
padding++;
if (c != EOF)
ungetc(c, in_file);
}
samples = lame_decode_initfile(in_file, mp3data, format);
if (verbose) {
tc_log_info(__FILE__, "channels=%d, samplerate=%d Hz, bitrate=%d kbps, (%d)",
mp3data->stereo, mp3data->samplerate, mp3data->bitrate,
mp3data->framesize);
}
if (format == MP3_AUDIO_ID) {
if (decode->padrate > 0) {
padding = (int)((double)padding / (double)decode->padrate * mp3data->samplerate)
* mp3data->stereo * 2;
memset(buffer, 0, sizeof(buffer));
while (padding >= sizeof(buffer)) {
if (tc_pwrite(decode->fd_out, (uint8_t *)buffer, sizeof(buffer)) != sizeof(buffer)) {
tc_log_error(__FILE__, "error while writing padding output data");
import_exit(1);
}
padding -= sizeof(buffer);
}
if (padding && tc_pwrite(decode->fd_out, (uint8_t *)buffer, padding) != padding) {
tc_log_error(__FILE__, "error while writing final padding output data");
import_exit(1);
}
}
}
// decoder loop
channels = mp3data->stereo;
while ((samples=lame_decode_fromfile(in_file, ch1, ch2, mp3data)) > 0) {
// interleave data
j = 0;
switch (channels) {
case 1: // mono
ac_memcpy (buffer, ch1, samples * sizeof(uint16_t));
break;
case 2: // stereo
for (i=0; i < samples; i++) {
*(buffer+j+0) = ch1[i];
*(buffer+j+1) = ch2[i];
j+=2;
}
break;
}
bytes = samples * channels * sizeof(uint16_t);
if (tc_pwrite(decode->fd_out, (uint8_t *) buffer, bytes) != bytes) {
tc_log_error(__FILE__, "error while writing output data");
import_exit(1);
break; /* broken pipe */
}
}
import_exit(0);
#else // HAVE_LAME
tc_log_error(__FILE__, "no lame support available");
import_exit(1);
#endif
}
void decode_mp3(decode_t *decode)
{
decode_mpaudio(decode, MP3_AUDIO_ID);
}
void decode_mp2(decode_t *decode)
{
decode_mpaudio(decode, MP2_AUDIO_ID);
}
/*************************************************************************/
/*
* Local variables:
* c-file-style: "stroustrup"
* c-file-offsets: ((case-label . *) (statement-case-intro . *))
* indent-tabs-mode: nil
* End:
*
* vim: expandtab shiftwidth=4:
*/
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