* The simplest AC3 encoder
* Copyright (c) 2000 Fabrice Bellard.
*
- * This library is free software; you can redistribute it and/or
+ * 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 of the License, or (at your option) any later version.
+ * version 2.1 of the License, or (at your option) any later version.
*
- * This library is distributed in the hope that it will be useful,
+ * 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 this library; if not, write to the Free Software
+ * License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
//#define DEBUG_BITALLOC
#include "avcodec.h"
#include "bitstream.h"
+#include "crc.h"
#include "ac3.h"
typedef struct AC3EncodeContext {
unsigned int bsid;
unsigned int frame_size_min; /* minimum frame size in case rounding is necessary */
unsigned int frame_size; /* current frame size in words */
+ unsigned int bits_written;
+ unsigned int samples_written;
int halfratecod;
unsigned int frmsizecod;
unsigned int fscod; /* frequency */
#define EXP_DIFF_THRESHOLD 1000
static void fft_init(int ln);
-static void ac3_crc_init(void);
static inline int16_t fix15(float a)
{
bit_alloc(s, bap, encoded_exp, exp_strategy, frame_bits, csnroffst, 0) < 0)
csnroffst -= SNR_INC1;
if (csnroffst < 0) {
- av_log(NULL, AV_LOG_ERROR, "Yack, Error !!!\n");
+ av_log(NULL, AV_LOG_ERROR, "Bit allocation failed, try increasing the bitrate, -ab 384 for example!\n");
return -1;
}
while ((csnroffst + SNR_INC1) <= 63 &&
for(j=0;j<v;j++) masktab[k++]=i;
l += v;
}
- bndtab[50] = 0;
+ bndtab[50] = l;
}
s->bit_rate = bitrate;
s->frmsizecod = i << 1;
s->frame_size_min = (bitrate * 1000 * AC3_FRAME_SIZE) / (freq * 16);
- /* for now we do not handle fractional sizes */
+ s->bits_written = 0;
+ s->samples_written = 0;
s->frame_size = s->frame_size_min;
/* bit allocation init */
xsin1[i] = fix15(-sin(alpha));
}
- ac3_crc_init();
-
avctx->coded_frame= avcodec_alloc_frame();
avctx->coded_frame->key_frame= 1;
}
}
-/* compute the ac3 crc */
-
#define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
-static void ac3_crc_init(void)
-{
- unsigned int c, n, k;
-
- for(n=0;n<256;n++) {
- c = n << 8;
- for (k = 0; k < 8; k++) {
- if (c & (1 << 15))
- c = ((c << 1) & 0xffff) ^ (CRC16_POLY & 0xffff);
- else
- c = c << 1;
- }
- crc_table[n] = c;
- }
-}
-
-static unsigned int ac3_crc(uint8_t *data, int n, unsigned int crc)
-{
- int i;
- for(i=0;i<n;i++) {
- crc = (crc_table[data[i] ^ (crc >> 8)] ^ (crc << 8)) & 0xffff;
- }
- return crc;
-}
-
static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
{
unsigned int c;
/* Now we must compute both crcs : this is not so easy for crc1
because it is at the beginning of the data... */
frame_size_58 = (frame_size >> 1) + (frame_size >> 3);
- crc1 = ac3_crc(frame + 4, (2 * frame_size_58) - 4, 0);
+ crc1 = bswap_16(av_crc(av_crc8005, 0, frame + 4, 2 * frame_size_58 - 4));
/* XXX: could precompute crc_inv */
crc_inv = pow_poly((CRC16_POLY >> 1), (16 * frame_size_58) - 16, CRC16_POLY);
crc1 = mul_poly(crc_inv, crc1, CRC16_POLY);
frame[2] = crc1 >> 8;
frame[3] = crc1;
- crc2 = ac3_crc(frame + 2 * frame_size_58, (frame_size - frame_size_58) * 2 - 2, 0);
+ crc2 = bswap_16(av_crc(av_crc8005, 0, frame + 2 * frame_size_58, (frame_size - frame_size_58) * 2 - 2));
frame[2*frame_size - 2] = crc2 >> 8;
frame[2*frame_size - 1] = crc2;
v = 14 - log2_tab(input_samples, N);
if (v < 0)
v = 0;
- exp_samples[i][ch] = v - 8;
+ exp_samples[i][ch] = v - 9;
lshift_tab(input_samples, N, v);
/* do the MDCT */
}
}
+ /* adjust for fractional frame sizes */
+ while(s->bits_written >= s->bit_rate*1000 && s->samples_written >= s->sample_rate) {
+ s->bits_written -= s->bit_rate*1000;
+ s->samples_written -= s->sample_rate;
+ }
+ s->frame_size = s->frame_size_min + (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate*1000);
+ s->bits_written += s->frame_size * 16;
+ s->samples_written += AC3_FRAME_SIZE;
+
compute_bit_allocation(s, bap, encoded_exp, exp_strategy, frame_bits);
/* everything is known... let's output the frame */
output_frame_header(s, frame);