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/*
* A52 decoder using liba52
* Copyright (c) 2001 Fabrice Bellard.
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file a52dec.c
* A52 decoder using liba52
*/
#include "avcodec.h"
#include <a52dec/a52.h>
#ifdef CONFIG_LIBA52BIN
#include <dlfcn.h>
static const char* liba52name = "liba52.so.0";
#endif
/**
* liba52 - Copyright (C) Aaron Holtzman
* released under the GPL license.
*/
typedef struct AC3DecodeState {
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_LIBA52BIN
static void* dlsymm(void* handle, const char* symbol)
{
void* f = dlsym(handle, symbol);
if (!f)
av_log( NULL, AV_LOG_ERROR, "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_LIBA52BIN
s->handle = dlopen(liba52name, RTLD_LAZY);
if (!s->handle)
{
av_log( avctx, AV_LOG_ERROR, "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
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);
/* allow downmixing to stereo or mono */
if (avctx->channels > 0 && avctx->request_channels > 0 &&
avctx->request_channels < avctx->channels &&
avctx->request_channels <= 2) {
avctx->channels = avctx->request_channels;
}
return 0;
}
/**** the following function comes from a52dec */
static inline void float_to_int (float * _f, int16_t * 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++] = av_clip_int16(f[i + c] - 0x43c00000);
}
}
/**** end */
#define HEADER_SIZE 7
static int a52_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
uint8_t *buf, int buf_size)
{
AC3DecodeState *s = avctx->priv_data;
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;
if (buf_size < HEADER_SIZE) {
av_log(avctx, AV_LOG_ERROR, "Error decoding frame, not enough bytes for header\n");
return -1;
}
len = s->a52_syncinfo(buf, &s->flags, &sample_rate, &bit_rate);
if (len == 0) {
av_log(avctx, AV_LOG_ERROR, "Error decoding frame, no sync byte at begin\n");
return -1;
}
if (buf_size < len) {
av_log(avctx, AV_LOG_ERROR, "Error decoding frame, not enough bytes\n");
return -1;
}
/* update codec info */
avctx->sample_rate = sample_rate;
s->channels = ac3_channels[s->flags & 7];
if (s->flags & A52_LFE)
s->channels++;
if (avctx->request_channels > 0 &&
avctx->request_channels <= 2 &&
avctx->request_channels < s->channels) {
avctx->channels = avctx->request_channels;
} else {
avctx->channels = s->channels;
}
avctx->bit_rate = bit_rate;
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, buf, &flags, &level, 384)) {
fail:
av_log(avctx, AV_LOG_ERROR, "Error decoding frame\n");
return -1;
}
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);
}
*data_size = 6 * avctx->channels * 256 * sizeof(int16_t);
return len;
}
static int a52_decode_end(AVCodecContext *avctx)
{
AC3DecodeState *s = avctx->priv_data;
s->a52_free(s->state);
#ifdef CONFIG_LIBA52BIN
dlclose(s->handle);
#endif
return 0;
}
AVCodec liba52_decoder = {
"liba52",
CODEC_TYPE_AUDIO,
CODEC_ID_AC3,
sizeof(AC3DecodeState),
a52_decode_init,
NULL,
a52_decode_end,
a52_decode_frame,
};
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