mirror of https://git.ffmpeg.org/ffmpeg.git
251 lines
7.6 KiB
C
251 lines
7.6 KiB
C
/*
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* A52 decoder
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* Copyright (c) 2001 Fabrice Bellard.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "avcodec.h"
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#include "liba52/a52.h"
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#ifdef CONFIG_A52BIN
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#include <dlfcn.h>
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static const char* liba52name = "liba52.so.0";
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#endif
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/**
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* liba52 - Copyright (C) Aaron Holtzman
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* released under the GPL license.
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*/
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typedef struct AC3DecodeState {
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UINT8 inbuf[4096]; /* input buffer */
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UINT8 *inbuf_ptr;
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int frame_size;
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int flags;
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int channels;
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a52_state_t* state;
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sample_t* samples;
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/*
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* virtual method table
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*
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* using this function table so the liba52 doesn't
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* have to be really linked together with ffmpeg
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* and might be linked in runtime - this allows binary
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* distribution of ffmpeg library which doens't depend
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* on liba52 library - but if user has it installed
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* it will be used - user might install such library
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* separately
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*/
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void* handle;
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a52_state_t* (*a52_init)(uint32_t mm_accel);
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sample_t* (*a52_samples)(a52_state_t * state);
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int (*a52_syncinfo)(uint8_t * buf, int * flags,
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int * sample_rate, int * bit_rate);
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int (*a52_frame)(a52_state_t * state, uint8_t * buf, int * flags,
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sample_t * level, sample_t bias);
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void (*a52_dynrng)(a52_state_t * state,
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sample_t (* call) (sample_t, void *), void * data);
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int (*a52_block)(a52_state_t * state);
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void (*a52_free)(a52_state_t * state);
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} AC3DecodeState;
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#ifdef CONFIG_A52BIN
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static void* dlsymm(void* handle, const char* symbol)
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{
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void* f = dlsym(handle, symbol);
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if (!f)
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fprintf(stderr, "A52 Decoder - function '%s' can't be resolved\n", symbol);
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return f;
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}
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#endif
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static int a52_decode_init(AVCodecContext *avctx)
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{
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AC3DecodeState *s = avctx->priv_data;
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#ifdef CONFIG_A52BIN
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s->handle = dlopen(liba52name, RTLD_LAZY);
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if (!s->handle)
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{
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fprintf(stderr, "A52 library %s could not be opened! \n%s\n", liba52name, dlerror());
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return -1;
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}
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s->a52_init = (a52_state_t* (*)(uint32_t)) dlsymm(s->handle, "a52_init");
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s->a52_samples = (sample_t* (*)(a52_state_t*)) dlsymm(s->handle, "a52_samples");
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s->a52_syncinfo = (int (*)(uint8_t*, int*, int*, int*)) dlsymm(s->handle, "a52_syncinfo");
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s->a52_frame = (int (*)(a52_state_t*, uint8_t*, int*, sample_t*, sample_t)) dlsymm(s->handle, "a52_frame");
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s->a52_block = (int (*)(a52_state_t*)) dlsymm(s->handle, "a52_block");
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s->a52_free = (void (*)(a52_state_t*)) dlsymm(s->handle, "a52_free");
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if (!s->a52_init || !s->a52_samples || !s->a52_syncinfo
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|| !s->a52_frame || !s->a52_block || !s->a52_free)
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{
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dlclose(s->handle);
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return -1;
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}
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#else
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/* static linked version */
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s->handle = 0;
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s->a52_init = a52_init;
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s->a52_samples = a52_samples;
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s->a52_syncinfo = a52_syncinfo;
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s->a52_frame = a52_frame;
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s->a52_block = a52_block;
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s->a52_free = a52_free;
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#endif
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s->state = s->a52_init(0); /* later use CPU flags */
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s->samples = s->a52_samples(s->state);
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s->inbuf_ptr = s->inbuf;
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s->frame_size = 0;
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return 0;
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}
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/**** the following two functions comes from a52dec */
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static inline int blah (int32_t i)
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{
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if (i > 0x43c07fff)
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return 32767;
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else if (i < 0x43bf8000)
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return -32768;
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return i - 0x43c00000;
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}
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static inline void float_to_int (float * _f, INT16 * s16, int nchannels)
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{
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int i, j, c;
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int32_t * f = (int32_t *) _f; // XXX assumes IEEE float format
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j = 0;
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nchannels *= 256;
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for (i = 0; i < 256; i++) {
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for (c = 0; c < nchannels; c += 256)
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s16[j++] = blah (f[i + c]);
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}
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}
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/**** end */
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#define HEADER_SIZE 7
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static int a52_decode_frame(AVCodecContext *avctx,
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void *data, int *data_size,
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UINT8 *buf, int buf_size)
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{
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AC3DecodeState *s = avctx->priv_data;
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UINT8 *buf_ptr;
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int flags, i, len;
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int sample_rate, bit_rate;
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short *out_samples = data;
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float level;
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static const int ac3_channels[8] = {
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2, 1, 2, 3, 3, 4, 4, 5
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};
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*data_size = 0;
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buf_ptr = buf;
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while (buf_size > 0) {
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len = s->inbuf_ptr - s->inbuf;
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if (s->frame_size == 0) {
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/* no header seen : find one. We need at least 7 bytes to parse it */
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len = HEADER_SIZE - len;
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if (len > buf_size)
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len = buf_size;
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memcpy(s->inbuf_ptr, buf_ptr, len);
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buf_ptr += len;
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s->inbuf_ptr += len;
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buf_size -= len;
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if ((s->inbuf_ptr - s->inbuf) == HEADER_SIZE) {
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len = s->a52_syncinfo(s->inbuf, &s->flags, &sample_rate, &bit_rate);
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if (len == 0) {
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/* no sync found : move by one byte (inefficient, but simple!) */
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memcpy(s->inbuf, s->inbuf + 1, HEADER_SIZE - 1);
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s->inbuf_ptr--;
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} else {
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s->frame_size = len;
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/* update codec info */
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avctx->sample_rate = sample_rate;
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s->channels = ac3_channels[s->flags & 7];
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if (s->flags & A52_LFE)
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s->channels++;
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if (avctx->channels == 0)
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/* No specific number of channel requested */
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avctx->channels = s->channels;
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else if (s->channels < avctx->channels) {
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fprintf(stderr, "ac3dec: AC3 Source channels are less than specified: output to %d channels.. (frmsize: %d)\n", s->channels, len);
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avctx->channels = s->channels;
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}
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avctx->bit_rate = bit_rate;
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}
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}
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} else if (len < s->frame_size) {
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len = s->frame_size - len;
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if (len > buf_size)
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len = buf_size;
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memcpy(s->inbuf_ptr, buf_ptr, len);
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buf_ptr += len;
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s->inbuf_ptr += len;
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buf_size -= len;
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} else {
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flags = s->flags;
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if (avctx->channels == 1)
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flags = A52_MONO;
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else if (avctx->channels == 2)
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flags = A52_STEREO;
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else
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flags |= A52_ADJUST_LEVEL;
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level = 1;
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if (s->a52_frame(s->state, s->inbuf, &flags, &level, 384)) {
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fail:
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s->inbuf_ptr = s->inbuf;
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s->frame_size = 0;
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continue;
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}
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for (i = 0; i < 6; i++) {
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if (s->a52_block(s->state))
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goto fail;
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float_to_int(s->samples, out_samples + i * 256 * avctx->channels, avctx->channels);
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}
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s->inbuf_ptr = s->inbuf;
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s->frame_size = 0;
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*data_size = 6 * avctx->channels * 256 * sizeof(INT16);
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break;
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}
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}
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return buf_ptr - buf;
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}
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static int a52_decode_end(AVCodecContext *avctx)
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{
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AC3DecodeState *s = avctx->priv_data;
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s->a52_free(s->state);
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#ifdef CONFIG_A52BIN
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dlclose(s->handle);
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#endif
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return 0;
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}
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AVCodec ac3_decoder = {
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"ac3",
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CODEC_TYPE_AUDIO,
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CODEC_ID_AC3,
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sizeof(AC3DecodeState),
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a52_decode_init,
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NULL,
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a52_decode_end,
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a52_decode_frame,
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};
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