FFmpeg: libavcodec/ac3enc_fixed.c Source File
Go to the documentation of this file. 1 /*
2 * The simplest AC-3 encoder
3 * Copyright (c) 2000 Fabrice Bellard
4 * Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com>
5 * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
6 *
7 * This file is part of FFmpeg.
8 *
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 */
23
24 /**
25 * @file
26 * fixed-point AC-3 encoder.
27 */
28
29 #define AC3ENC_FLOAT 0
35
39 {
40 s->ac3dsp.sum_square_butterfly_int32(sum, coef0, coef1,
len);
41 }
42
43 /*
44 * Clip MDCT coefficients to allowable range.
45 */
48 {
50 }
51
52
53 /*
54 * Calculate a single coupling coordinate.
55 */
57 {
59 return 1048576;
60 } else {
61 uint64_t coord = energy_ch / (energy_cpl >> 24);
62 uint32_t coord32 =
FFMIN(coord, 1073741824);
63 coord32 =
ff_sqrt(coord32) << 9;
65 }
66 }
67
69
70 /**
71 * Initialize MDCT tables.
72 *
73 * @param s AC-3 encoder private context
74 * @return 0 on success, negative error code on failure
75 */
77 {
79 const float scale = -1.0f;
80
81 int32_t *iwin =
s->mdct_window_fixed;
82
85 iwin[
i] =
lrintf(fwin[
i] * (1 << 22));
86
90
93 }
94
95
97 {
100
103
107
109 }
110
111
113 .
p.
name =
"ac3_fixed",
128 };
#define FF_CODEC_CAP_INIT_CLEANUP
The codec allows calling the close function for deallocation even if the init function returned a fai...
Filter the word "frame" indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
static av_cold int ac3_fixed_mdct_init(AVCodecContext *avctx, AC3EncodeContext *s)
Initialize MDCT tables.
@ AV_SAMPLE_FMT_S32P
signed 32 bits, planar
int ff_ac3_encode_frame(AVCodecContext *avctx, AVPacket *avpkt, const AVFrame *frame, int *got_packet_ptr)
av_cold int av_tx_init(AVTXContext **ctx, av_tx_fn *tx, enum AVTXType type, int inv, int len, const void *scale, uint64_t flags)
Initialize a transform context with the given configuration (i)MDCTs with an odd length are currently...
static int encode_frame(OutputFile *of, OutputStream *ost, AVFrame *frame, AVPacket *pkt)
void(* vector_clip_int32)(int32_t *dst, const int32_t *src, int32_t min, int32_t max, unsigned int len)
Clip each element in an array of int32_t to a given minimum and maximum value.
AVCodec p
The public AVCodec.
int flags
AV_CODEC_FLAG_*.
AVFixedDSPContext * avpriv_alloc_fixed_dsp(int bit_exact)
Allocate and initialize a fixed DSP context.
#define FF_CODEC_ENCODE_CB(func)
static av_cold int ac3_fixed_encode_init(AVCodecContext *avctx)
const AVChannelLayout ff_ac3_ch_layouts[19]
List of supported channel layouts.
#define AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE
This encoder can reorder user opaque values from input AVFrames and return them with corresponding ou...
#define CODEC_LONG_NAME(str)
const FFCodec ff_ac3_fixed_encoder
AC-3 encoder private context.
int(* init)(AVBSFContext *ctx)
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() or get_encode_buffer() for allocating buffers and supports custom allocators.
static void clip_coefficients(AudioDSPContext *adsp, int32_t *coef, unsigned int len)
static CoefType calc_cpl_coord(CoefSumType energy_ch, CoefSumType energy_cpl)
#define CODEC_SAMPLEFMTS(...)
const int ff_ac3_sample_rate_tab[]
#define i(width, name, range_min, range_max)
const char * name
Name of the codec implementation.
static void sum_square_butterfly(AC3EncodeContext *s, int64_t sum[4], const int32_t *coef0, const int32_t *coef1, int len)
main external API structure.
#define CODEC_SAMPLERATES_ARRAY(array)
av_cold void ff_kbd_window_init(float *window, float alpha, int n)
Generate a Kaiser-Bessel Derived Window.
const AVClass ff_ac3enc_class
const FFCodecDefault ff_ac3_enc_defaults[]
av_cold int ff_ac3_encode_init(AVCodecContext *avctx)
#define AV_CODEC_FLAG_BITEXACT
Use only bitexact stuff (except (I)DCT).
static void scale(int *out, const int *in, const int w, const int h, const int shift)
av_cold int ff_ac3_encode_close(AVCodecContext *avctx)
Finalize encoding and free any memory allocated by the encoder.
#define CODEC_CH_LAYOUTS_ARRAY(array)
Generated on Tue Nov 18 2025 19:21:57 for FFmpeg by
doxygen
1.8.17