/*
- * The simplest AC3 encoder
+ * The simplest AC-3 encoder
* Copyright (c) 2000 Fabrice Bellard.
*
* This file is part of FFmpeg.
/**
* @file ac3enc.c
- * The simplest AC3 encoder.
+ * The simplest AC-3 encoder.
*/
//#define DEBUG
//#define DEBUG_BITALLOC
+#include "libavutil/crc.h"
#include "avcodec.h"
#include "bitstream.h"
-#include "crc.h"
#include "ac3.h"
typedef struct AC3EncodeContext {
static int16_t costab[64];
static int16_t sintab[64];
-static int16_t fft_rev[512];
static int16_t xcos1[128];
static int16_t xsin1[128];
/* new exponents are sent if their Norm 1 exceed this number */
#define EXP_DIFF_THRESHOLD 1000
-static void fft_init(int ln);
-
static inline int16_t fix15(float a)
{
int v;
static void fft_init(int ln)
{
- int i, j, m, n;
+ int i, n;
float alpha;
n = 1 << ln;
costab[i] = fix15(cos(alpha));
sintab[i] = fix15(sin(alpha));
}
-
- for(i=0;i<n;i++) {
- m=0;
- for(j=0;j<ln;j++) {
- m |= ((i >> j) & 1) << (ln-j-1);
- }
- fft_rev[i]=m;
- }
}
/* butter fly op */
/* reverse */
for(j=0;j<np;j++) {
- int k;
- IComplex tmp;
- k = fft_rev[j];
- if (k < j) {
- tmp = z[k];
- z[k] = z[j];
- z[j] = tmp;
- }
+ int k = ff_reverse[j] >> (8 - ln);
+ if (k < j)
+ FFSWAP(IComplex, z[k], z[j]);
}
/* pass 0 */
for(ch=0;ch<s->nb_all_channels;ch++) {
ff_ac3_bit_alloc_calc_bap(mask[i][ch], psd[i][ch], 0,
s->nb_coefs[ch], snr_offset,
- s->bit_alloc.floor, bap[i][ch]);
+ s->bit_alloc.floor, ff_ac3_bap_tab,
+ bap[i][ch]);
frame_bits += compute_mantissa_size(s, bap[i][ch],
s->nb_coefs[ch]);
}
uint8_t bap1[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50];
- static int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
+ static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
/* init default parameters */
s->slow_decay_code = 2;
return 0;
}
-static int AC3_encode_init(AVCodecContext *avctx)
+static av_cold int AC3_encode_init(AVCodecContext *avctx)
{
int freq = avctx->sample_rate;
int bitrate = avctx->bit_rate;
AC3EncodeContext *s = avctx->priv_data;
int i, j, ch;
float alpha;
+ int bw_code;
static const uint8_t channel_mode_defs[6] = {
0x01, /* C */
0x02, /* L R */
s->frame_size = s->frame_size_min;
/* bit allocation init */
+ if(avctx->cutoff) {
+ /* calculate bandwidth based on user-specified cutoff frequency */
+ int cutoff = av_clip(avctx->cutoff, 1, s->sample_rate >> 1);
+ int fbw_coeffs = cutoff * 512 / s->sample_rate;
+ bw_code = av_clip((fbw_coeffs - 73) / 3, 0, 60);
+ } else {
+ /* use default bandwidth setting */
+ /* XXX: should compute the bandwidth according to the frame
+ size, so that we avoid annoying high frequency artifacts */
+ bw_code = 50;
+ }
for(ch=0;ch<s->nb_channels;ch++) {
/* bandwidth for each channel */
- /* XXX: should compute the bandwidth according to the frame
- size, so that we avoid anoying high freq artefacts */
- s->chbwcod[ch] = 50; /* sample bandwidth as mpeg audio layer 2 table 0 */
- s->nb_coefs[ch] = ((s->chbwcod[ch] + 12) * 3) + 37;
+ s->chbwcod[ch] = bw_code;
+ s->nb_coefs[ch] = bw_code * 3 + 73;
}
if (s->lfe) {
s->nb_coefs[s->lfe_channel] = 7; /* fixed */
return 0;
}
-/* output the AC3 frame header */
+/* output the AC-3 frame header */
static void output_frame_header(AC3EncodeContext *s, unsigned char *frame)
{
init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
return v & ((1 << qbits)-1);
}
-/* Output one audio block. There are NB_BLOCKS audio blocks in one AC3
+/* Output one audio block. There are NB_BLOCKS audio blocks in one AC-3
frame */
static void output_audio_block(AC3EncodeContext *s,
uint8_t exp_strategy[AC3_MAX_CHANNELS],
/* 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 = bswap_16(av_crc(av_crc8005, 0, frame + 4, 2 * frame_size_58 - 4));
+ crc1 = bswap_16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 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);
AV_WB16(frame+2,crc1);
- crc2 = bswap_16(av_crc(av_crc8005, 0, frame + 2 * frame_size_58, (frame_size - frame_size_58) * 2 - 2));
+ crc2 = bswap_16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
+ frame + 2 * frame_size_58,
+ (frame_size - frame_size_58) * 2 - 2));
AV_WB16(frame+2*frame_size-2,crc2);
// printf("n=%d frame_size=%d\n", n, frame_size);
return output_frame_end(s);
}
-static int AC3_encode_close(AVCodecContext *avctx)
+static av_cold int AC3_encode_close(AVCodecContext *avctx)
{
av_freep(&avctx->coded_frame);
return 0;
AC3_encode_frame,
AC3_encode_close,
NULL,
+ .sample_fmts = (enum SampleFormat[]){SAMPLE_FMT_S16,SAMPLE_FMT_NONE},
+ .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52 / AC-3"),
};
projects / ffmpeg / blobdiff