/*
* AC3 decoder
- * Copyright (c) 2001 Gerard Lantau.
+ * Copyright (c) 2001 Fabrice Bellard.
*
- * 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 library 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 of the License, or (at your option) any later version.
*
- * This program is distributed in the hope that it will be useful,
+ * This library 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.
+ * 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 General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
+
+/**
+ * @file ac3dec.c
+ * AC3 decoder.
+ */
+
+//#define DEBUG
+
#include "avcodec.h"
#include "libac3/ac3.h"
/* currently, I use libac3 which is Copyright (C) Aaron Holtzman and
released under the GPL license. I may reimplement it someday... */
typedef struct AC3DecodeState {
- UINT8 inbuf[4096]; /* input buffer */
- UINT8 *inbuf_ptr;
+ uint8_t inbuf[4096]; /* input buffer */
+ uint8_t *inbuf_ptr;
int frame_size;
int flags;
+ int channels;
ac3_state_t state;
} AC3DecodeState;
static inline int blah (int32_t i)
{
if (i > 0x43c07fff)
- return 32767;
+ return 32767;
else if (i < 0x43bf8000)
- return -32768;
+ return -32768;
else
- return i - 0x43c00000;
-}
-
-static inline void float_to_int (float * _f, INT16 * s16)
-{
- int i;
- int32_t * f = (int32_t *) _f; // XXX assumes IEEE float format
-
- for (i = 0; i < 256; i++) {
- s16[2*i] = blah (f[i]);
- s16[2*i+1] = blah (f[i+256]);
- }
+ return i - 0x43c00000;
}
-static inline void float_to_int_mono (float * _f, INT16 * s16)
+static inline void float_to_int (float * _f, int16_t * s16, int nchannels)
{
- int i;
- int32_t * f = (int32_t *) _f; // XXX assumes IEEE float format
+ 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++) {
- s16[i] = blah (f[i]);
+ for (c = 0; c < nchannels; c += 256)
+ s16[j++] = blah (f[i + c]);
}
}
#define HEADER_SIZE 7
-static int ac3_decode_frame(AVCodecContext *avctx,
+static int ac3_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
- UINT8 *buf, int buf_size)
+ uint8_t *buf, int buf_size)
{
AC3DecodeState *s = avctx->priv_data;
- UINT8 *buf_ptr;
+ uint8_t *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;
s->frame_size = len;
/* update codec info */
avctx->sample_rate = sample_rate;
- if ((s->flags & AC3_CHANNEL_MASK) == AC3_MONO)
- avctx->channels = 1;
- else
- avctx->channels = 2;
+ s->channels = ac3_channels[s->flags & 7];
+ if (s->flags & AC3_LFE)
+ s->channels++;
+ if (avctx->channels == 0)
+ /* No specific number of channel requested */
+ avctx->channels = s->channels;
+ else if (s->channels < avctx->channels) {
+ av_log( avctx, AV_LOG_INFO, "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;
}
}
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 = AC3_MONO;
- else
+ else if (avctx->channels == 2)
flags = AC3_STEREO;
-
- flags |= AC3_ADJUST_LEVEL;
+ else
+ flags |= AC3_ADJUST_LEVEL;
level = 1;
if (ac3_frame (&s->state, s->inbuf, &flags, &level, 384)) {
fail:
for (i = 0; i < 6; i++) {
if (ac3_block (&s->state))
goto fail;
- if (avctx->channels == 1)
- float_to_int_mono (*samples, out_samples + i * 256);
- else
- float_to_int (*samples, out_samples + i * 512);
+ float_to_int (*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);
+ *data_size = 6 * avctx->channels * 256 * sizeof(int16_t);
break;
}
}
projects / ffmpeg / blobdiff