mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
136 lines
3.6 KiB
136 lines
3.6 KiB
/* |
|
* The simplest AC-3 encoder |
|
* Copyright (c) 2000 Fabrice Bellard |
|
* Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com> |
|
* Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de> |
|
* |
|
* This file is part of Libav. |
|
* |
|
* Libav 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. |
|
* |
|
* Libav 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 Libav; if not, write to the Free Software |
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
|
*/ |
|
|
|
/** |
|
* @file |
|
* floating-point AC-3 encoder. |
|
*/ |
|
|
|
#define CONFIG_AC3ENC_FLOAT 1 |
|
#include "ac3enc.h" |
|
#include "eac3enc.h" |
|
#include "kbdwin.h" |
|
|
|
|
|
#if CONFIG_AC3_ENCODER |
|
#define AC3ENC_TYPE AC3ENC_TYPE_AC3 |
|
#include "ac3enc_opts_template.c" |
|
static const AVClass ac3enc_class = { "AC-3 Encoder", av_default_item_name, |
|
ac3_options, LIBAVUTIL_VERSION_INT }; |
|
#endif |
|
|
|
#include "ac3enc_template.c" |
|
|
|
|
|
/** |
|
* Finalize MDCT and free allocated memory. |
|
*/ |
|
av_cold void ff_ac3_float_mdct_end(AC3EncodeContext *s) |
|
{ |
|
ff_mdct_end(&s->mdct); |
|
av_freep(&s->mdct_window); |
|
} |
|
|
|
|
|
/** |
|
* Initialize MDCT tables. |
|
* @param nbits log2(MDCT size) |
|
*/ |
|
av_cold int ff_ac3_float_mdct_init(AC3EncodeContext *s) |
|
{ |
|
float *window; |
|
int i, n, n2; |
|
|
|
n = 1 << 9; |
|
n2 = n >> 1; |
|
|
|
window = av_malloc(n * sizeof(*window)); |
|
if (!window) { |
|
av_log(s->avctx, AV_LOG_ERROR, "Cannot allocate memory.\n"); |
|
return AVERROR(ENOMEM); |
|
} |
|
ff_kbd_window_init(window, 5.0, n2); |
|
for (i = 0; i < n2; i++) |
|
window[n-1-i] = window[i]; |
|
s->mdct_window = window; |
|
|
|
return ff_mdct_init(&s->mdct, 9, 0, -2.0 / n); |
|
} |
|
|
|
|
|
/** |
|
* Apply KBD window to input samples prior to MDCT. |
|
*/ |
|
static void apply_window(DSPContext *dsp, float *output, const float *input, |
|
const float *window, unsigned int len) |
|
{ |
|
dsp->vector_fmul(output, input, window, len); |
|
} |
|
|
|
|
|
/** |
|
* Normalize the input samples. |
|
* Not needed for the floating-point encoder. |
|
*/ |
|
static int normalize_samples(AC3EncodeContext *s) |
|
{ |
|
return 0; |
|
} |
|
|
|
|
|
/** |
|
* Scale MDCT coefficients from float to 24-bit fixed-point. |
|
*/ |
|
static void scale_coefficients(AC3EncodeContext *s) |
|
{ |
|
int chan_size = AC3_MAX_COEFS * s->num_blocks; |
|
s->ac3dsp.float_to_fixed24(s->fixed_coef_buffer + chan_size, |
|
s->mdct_coef_buffer + chan_size, |
|
chan_size * s->channels); |
|
} |
|
|
|
|
|
/** |
|
* Clip MDCT coefficients to allowable range. |
|
*/ |
|
static void clip_coefficients(DSPContext *dsp, float *coef, unsigned int len) |
|
{ |
|
dsp->vector_clipf(coef, coef, COEF_MIN, COEF_MAX, len); |
|
} |
|
|
|
|
|
#if CONFIG_AC3_ENCODER |
|
AVCodec ff_ac3_encoder = { |
|
.name = "ac3", |
|
.type = AVMEDIA_TYPE_AUDIO, |
|
.id = CODEC_ID_AC3, |
|
.priv_data_size = sizeof(AC3EncodeContext), |
|
.init = ff_ac3_encode_init, |
|
.encode = ff_ac3_float_encode_frame, |
|
.close = ff_ac3_encode_close, |
|
.sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_FLT,AV_SAMPLE_FMT_NONE}, |
|
.long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"), |
|
.priv_class = &ac3enc_class, |
|
.channel_layouts = ff_ac3_channel_layouts, |
|
}; |
|
#endif
|
|
|