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/*
* A52 decoder
* Copyright (c) 2001 Gerard Lantau.
*
* 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.
*/
#include "avcodec.h"
#include "liba52/a52.h"
#ifdef CONFIG_A52BIN
#include <dlfcn.h>
static const char* liba52name = "liba52.so.0";
#endif
/**
* liba52 - Copyright (C) Aaron Holtzman
* released under the GPL license.
*/
typedef struct AC3DecodeState {
UINT8 inbuf[4096]; /* input buffer */
UINT8 *inbuf_ptr;
int frame_size;
int flags;
int channels;
a52_state_t* state;
sample_t* samples;
/*
* virtual method table
*
* using this function table so the liba52 doesn't
* have to be really linked together with ffmpeg
* and might be linked in runtime - this allows binary
* distribution of ffmpeg library which doens't depend
* on liba52 library - but if user has it installed
* it will be used - user might install such library
* separately
*/
void* handle;
a52_state_t* (*a52_init)(uint32_t mm_accel);
sample_t* (*a52_samples)(a52_state_t * state);
int (*a52_syncinfo)(uint8_t * buf, int * flags,
int * sample_rate, int * bit_rate);
int (*a52_frame)(a52_state_t * state, uint8_t * buf, int * flags,
sample_t * level, sample_t bias);
void (*a52_dynrng)(a52_state_t * state,
sample_t (* call) (sample_t, void *), void * data);
int (*a52_block)(a52_state_t * state);
void (*a52_free)(a52_state_t * state);
} AC3DecodeState;
#ifdef CONFIG_A52BIN
static void* dlsymm(void* handle, const char* symbol)
{
void* f = dlsym(handle, symbol);
if (!f)
fprintf(stderr, "A52 Decoder - function '%s' can't be resolved\n", symbol);
return f;
}
#endif
static int a52_decode_init(AVCodecContext *avctx)
{
AC3DecodeState *s = avctx->priv_data;
#ifdef CONFIG_A52BIN
s->handle = dlopen(liba52name, RTLD_LAZY);
if (!s->handle)
{
fprintf(stderr, "A52 library %s could not be opened! \n%s\n", liba52name, dlerror());
return -1;
}
s->a52_init = (a52_state_t* (*)(uint32_t)) dlsymm(s->handle, "a52_init");
s->a52_samples = (sample_t* (*)(a52_state_t*)) dlsymm(s->handle, "a52_samples");
s->a52_syncinfo = (int (*)(uint8_t*, int*, int*, int*)) dlsymm(s->handle, "a52_syncinfo");
s->a52_frame = (int (*)(a52_state_t*, uint8_t*, int*, sample_t*, sample_t)) dlsymm(s->handle, "a52_frame");
s->a52_block = (int (*)(a52_state_t*)) dlsymm(s->handle, "a52_block");
s->a52_free = (void (*)(a52_state_t*)) dlsymm(s->handle, "a52_free");
if (!s->a52_init || !s->a52_samples || !s->a52_syncinfo
|| !s->a52_frame || !s->a52_block || !s->a52_free)
{
dlclose(s->handle);
return -1;
}
#else
/* static linked version */
s->handle = 0;
s->a52_init = a52_init;
s->a52_samples = a52_samples;
s->a52_syncinfo = a52_syncinfo;
s->a52_frame = a52_frame;
s->a52_block = a52_block;
s->a52_free = a52_free;
#endif
s->state = s->a52_init(0); /* later use CPU flags */
s->samples = s->a52_samples(s->state);
s->inbuf_ptr = s->inbuf;
s->frame_size = 0;
return 0;
}
/**** the following two functions comes from a52dec */
static inline int blah (int32_t i)
{
if (i > 0x43c07fff)
return 32767;
else if (i < 0x43bf8000)
return -32768;
return i - 0x43c00000;
}
static inline void float_to_int (float * _f, INT16 * s16, int nchannels)
{
int i, j, c;
int32_t * f = (int32_t *) _f; // XXX assumes IEEE float format
j = 0;
nchannels *= 256;
for (i = 0; i < 256; i++) {
for (c = 0; c < nchannels; c += 256)
s16[j++] = blah (f[i + c]);
}
}
/**** end */
#define HEADER_SIZE 7
static int a52_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
UINT8 *buf, int buf_size)
{
AC3DecodeState *s = avctx->priv_data;
UINT8 *buf_ptr;
int flags, i, len;
int sample_rate, bit_rate;
short *out_samples = data;
float level;
static const int ac3_channels[8] = {
2, 1, 2, 3, 3, 4, 4, 5
};
*data_size = 0;
buf_ptr = buf;
while (buf_size > 0) {
len = s->inbuf_ptr - s->inbuf;
if (s->frame_size == 0) {
/* no header seen : find one. We need at least 7 bytes to parse it */
len = HEADER_SIZE - len;
if (len > buf_size)
len = buf_size;
memcpy(s->inbuf_ptr, buf_ptr, len);
buf_ptr += len;
s->inbuf_ptr += len;
buf_size -= len;
if ((s->inbuf_ptr - s->inbuf) == HEADER_SIZE) {
len = s->a52_syncinfo(s->inbuf, &s->flags, &sample_rate, &bit_rate);
if (len == 0) {
/* no sync found : move by one byte (inefficient, but simple!) */
memcpy(s->inbuf, s->inbuf + 1, HEADER_SIZE - 1);
s->inbuf_ptr--;
} else {
s->frame_size = len;
/* update codec info */
avctx->sample_rate = sample_rate;
s->channels = ac3_channels[s->flags & 7];
if (s->flags & A52_LFE)
s->channels++;
if (avctx->channels == 0)
/* No specific number of channel requested */
avctx->channels = s->channels;
else if (s->channels < avctx->channels) {
fprintf(stderr, "ac3dec: AC3 Source channels are less than specified: output to %d channels.. (frmsize: %d)\n", s->channels, len);
avctx->channels = s->channels;
}
avctx->bit_rate = bit_rate;
}
}
} else if (len < s->frame_size) {
len = s->frame_size - len;
if (len > buf_size)
len = buf_size;
memcpy(s->inbuf_ptr, buf_ptr, len);
buf_ptr += len;
s->inbuf_ptr += len;
buf_size -= len;
} else {
flags = s->flags;
if (avctx->channels == 1)
flags = A52_MONO;
else if (avctx->channels == 2)
flags = A52_STEREO;
else
flags |= A52_ADJUST_LEVEL;
level = 1;
if (s->a52_frame(s->state, s->inbuf, &flags, &level, 384)) {
fail:
s->inbuf_ptr = s->inbuf;
s->frame_size = 0;
continue;
}
for (i = 0; i < 6; i++) {
if (s->a52_block(s->state))
goto fail;
float_to_int(s->samples, out_samples + i * 256 * avctx->channels, avctx->channels);
}
s->inbuf_ptr = s->inbuf;
s->frame_size = 0;
*data_size = 6 * avctx->channels * 256 * sizeof(INT16);
break;
}
}
return buf_ptr - buf;
}
static int a52_decode_end(AVCodecContext *avctx)
{
AC3DecodeState *s = avctx->priv_data;
s->a52_free(s->state);
#ifdef CONFIG_A52BIN
dlclose(s->handle);
#endif
return 0;
}
AVCodec ac3_decoder = {
"ac3",
CODEC_TYPE_AUDIO,
CODEC_ID_AC3,
sizeof(AC3DecodeState),
a52_decode_init,
NULL,
a52_decode_end,
a52_decode_frame,
};
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