FFmpeg
g728dec.c
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1 /*
2  * G.728 decoder
3  * Copyright (c) 2025 Peter Ross
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "avcodec.h"
23 #include "celp_filters.h"
24 #include "codec_internal.h"
25 #include "decode.h"
26 #include "get_bits.h"
27 #include "g728data.h"
28 #include "lpc_functions.h"
29 #include "ra288.h"
30 #include "libavutil/float_dsp.h"
31 #include "libavutil/mem.h"
32 #include "libavutil/mem_internal.h"
33 #include "libavutil/opt.h"
34 #include "libavutil/thread.h"
35 
36 #define MAX_BACKWARD_FILTER_ORDER LPC
37 #define MAX_BACKWARD_FILTER_LEN NFRSZ
38 #define MAX_BACKWARD_FILTER_NONREC NONR
39 #define ATTEN 0.75f
40 #include "g728_template.c"
41 
42 #define LPCW 10 /* Perceptual weighting filter order */
43 #define GOFF 32.0f /* Log-gain offset value */
44 
45 static float g728_gq_db[8];
46 static float g728_y_db[128];
47 static float g728_wnr_r[FFALIGN(NSBSZ,16)];
48 static float g728_wnrg_r[FFALIGN(NSBGSZ, 16)];
49 static float g728_facv_f[FFALIGN(LPC, 16)];
50 
51 static av_cold void g728_init_static_data(void)
52 {
53  for(int i = 0; i < FF_ARRAY_ELEMS(amptable); i++)
54  g728_gq_db[i] = 10.0f*log10f(amptable[i] * amptable[i]);
55 
56  for (int i = 0; i < FF_ARRAY_ELEMS(codetable); i++) {
57  float cby[IDIM];
58  for (int j = 0; j < IDIM; j++)
59  cby[j] = codetable[i][j] * (1.0f/(1<<11));
60  g728_y_db[i] = 10.0f*log10f(ff_scalarproduct_float_c(cby, cby, IDIM) / IDIM);
61  }
62 
63  for (int i = 0; i < NSBSZ; i++)
64  g728_wnr_r[i] = g728_wnr[NSBSZ - 1 - i] * (1.0f/(1<<15));
65  for (int i = 0; i < NSBGSZ; i++)
66  g728_wnrg_r[i] = g728_wnrg[NSBGSZ - 1 - i] * (1.0f/(1<<15));
67  for (int i = 0; i < LPC; i++)
68  g728_facv_f[i] = g728_facv[i] * (1.0f/(1<<14));
69 }
70 
71 typedef struct {
72  AVFloatDSPContext *fdsp;
73  int valid;
74  float a[LPC];
75  DECLARE_ALIGNED(32, float, sb)[NSBSZ];
76  DECLARE_ALIGNED(32, float, sbg)[NSBGSZ];
77  DECLARE_ALIGNED(32, float, gp)[FFALIGN(LPCLG, 16)];
78  DECLARE_ALIGNED(32, float, atmp)[FFALIGN(LPC, 16)];
79  float rexp[LPC + 1];
80  float rexpg[LPCLG + 1];
81  float r[LPC + 1];
82  float alpha;
83 } G728Context;
84 
85 static av_cold int g728_decode_init(AVCodecContext *avctx)
86 {
87  static AVOnce init_static_once = AV_ONCE_INIT;
88  G728Context *s = avctx->priv_data;
89 
90  s->fdsp = avpriv_float_dsp_alloc(avctx->flags & AV_CODEC_FLAG_BITEXACT);
91  if (!s->fdsp)
92  return AVERROR(ENOMEM);
93 
94  s->gp[0] = -1.0f;
95  for (int i = 0; i < NUPDATE; i++)
96  s->sbg[NSBGSZ - 1 -i] = -GOFF;
97 
98  avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
99 
100  av_channel_layout_uninit(&avctx->ch_layout);
101  avctx->ch_layout = (AVChannelLayout)AV_CHANNEL_LAYOUT_MONO;
102 
103  ff_thread_once(&init_static_once, g728_init_static_data);
104  return 0;
105 }
106 
107 static av_cold int g728_decode_close(AVCodecContext *avctx)
108 {
109  G728Context *s = avctx->priv_data;
110  av_freep(&s->fdsp);
111  return 0;
112 }
113 
114 static int hybrid_window(AVFloatDSPContext *fdsp,
115  int order, int n, int non_rec, float *out,
116  const float *hist, float *out2, const float *window)
117 {
118  do_hybrid_window(fdsp->vector_fmul, order, n, non_rec, out, hist, out2, window);
119  return out[order] != 0.0f;
120 }
121 
122 static void decode_frame(G728Context *s, GetBitContext *gb, float *dst)
123 {
124  float *gstate = s->sbg + NSBGSZ - 2;
125 
126  for (int idx = 0; idx < NUPDATE; idx++) {
127  DECLARE_ALIGNED(32, float, et)[IDIM];
128  float *statelpc = s->sb + NSBSZ - NFRSZ + idx*IDIM;
129  float gain, gain_db;
130  int is, ig;
131 
132  gain_db = 0.0f;
133  for (int i = 0; i < LPCLG; i++)
134  gain_db -= s->gp[i] * gstate[-i];
135  gain_db = av_clipf(gain_db, -GOFF, 28.0f);
136 
137  is = get_bits(gb, 7); // shape index
138  ig = get_bits(gb, 3); // gain index
139 
140  gain = powf(10.0f, (gain_db + GOFF) * .05f) * amptable[ig] * (1.0f/(1<<11));
141  for (int i = 0; i < IDIM; i++)
142  et[i] = codetable[is][i] * gain;
143 
144  ff_celp_lp_synthesis_filterf(statelpc, s->a, et, IDIM, LPC);
145 
146  for (int i = 0; i < IDIM; i++) {
147  statelpc[i] = av_clipf(statelpc[i], -4095.0f, 4095.0f);
148  dst[idx*IDIM + i] = statelpc[i] * (1.0f/(1<<12));
149  }
150 
151  gstate++;
152  *gstate = FFMAX(-GOFF, g728_gq_db[ig] + g728_y_db[is] + gain_db);
153 
154  if (idx == 0) {
155  DECLARE_ALIGNED(32, float, gptmp)[FFALIGN(LPCLG, 16)];
156  if (s->valid && (s->valid = !compute_lpc_coefs(s->r + 1, LPCW, LPC, s->atmp, 0, 0, 1, &s->alpha))) {
157  s->fdsp->vector_fmul(s->atmp, s->atmp, g728_facv_f, FFALIGN(LPC, 16));
158  }
159  if (hybrid_window(s->fdsp, LPCLG, NUPDATE, NONRLG, s->r, s->sbg, s->rexpg, g728_wnrg_r) &&
160  !compute_lpc_coefs(s->r, 0, LPCLG, gptmp, 0, 0, 1, &s->alpha)) {
161  s->fdsp->vector_fmul(s->gp, gptmp, gain_bw_tab, FFALIGN(LPCLG, 16));
162  }
163  memmove(s->sbg, s->sbg + NUPDATE, sizeof(float)*(LPCLG + NONRLG));
164  gstate = s->sbg + NSBGSZ - 1 - NUPDATE;
165  } else if (idx == 1) {
166  if (s->valid)
167  memcpy(s->a, s->atmp, sizeof(float)*LPC);
168  }
169  }
170 
171  s->valid = 0;
172  if (hybrid_window(s->fdsp, LPC, NFRSZ, NONR, s->r, s->sb, s->rexp, g728_wnr_r)) {
173  s->valid = !compute_lpc_coefs(s->r, 0, LPCW, s->atmp, 0, 0, 1, &s->alpha);
174  }
175 
176  memmove(s->sb, s->sb + NFRSZ, sizeof(float)*(LPC + NONR));
177 }
178 
179 static int g728_decode_frame(AVCodecContext *avctx, AVFrame *frame,
180  int *got_frame_ptr, AVPacket *avpkt)
181 {
182  G728Context *s = avctx->priv_data;
183  GetBitContext gb;
184  int ret;
185  int nb_frames = avpkt->size / 5;
186 
187  if (!nb_frames)
188  return AVERROR_INVALIDDATA;
189 
190  if ((ret = init_get_bits8(&gb, avpkt->data, avpkt->size)) < 0)
191  return ret;
192 
193 #define SAMPLES_PER_FRAME 20
194 
195  frame->nb_samples = nb_frames * SAMPLES_PER_FRAME;
196  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
197  return ret;
198 
199  for (int i = 0; i < nb_frames; i++)
200  decode_frame(s, &gb, (float *)frame->data[0] + i * 20);
201 
202  *got_frame_ptr = 1;
203 
204  return nb_frames * 5;
205 }
206 
207 const FFCodec ff_g728_decoder = {
208  .p.name = "g728",
209  CODEC_LONG_NAME("G.728)"),
210  .p.type = AVMEDIA_TYPE_AUDIO,
211  .p.id = AV_CODEC_ID_G728,
212  .priv_data_size = sizeof(G728Context),
213  .init = g728_decode_init,
214  .close = g728_decode_close,
215  FF_CODEC_DECODE_CB(g728_decode_frame),
216  .p.capabilities = AV_CODEC_CAP_CHANNEL_CONF |
217  AV_CODEC_CAP_DR1,
218 };
g728_wnrg
static const uint16_t g728_wnrg[NSBGSZ]
Definition: g728data.h:54
G728Context::fdsp
AVFloatDSPContext * fdsp
Definition: g728dec.c:72
r
const char * r
Definition: vf_curves.c:127
AVERROR
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
opt.h
g728_wnr_r
static float g728_wnr_r[FFALIGN(NSBSZ, 16)]
Definition: g728dec.c:47
mem_internal.h
out
FILE * out
Definition: movenc.c:55
is
The official guide to swscale for confused that is
Definition: swscale.txt:28
thread.h
codetable
static const int16_t codetable[128][5]
Definition: ra288.h:34
g728_decode_frame
static int g728_decode_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame_ptr, AVPacket *avpkt)
Definition: g728dec.c:179
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:410
AVPacket::data
uint8_t * data
Definition: packet.h:535
FFCodec
Definition: codec_internal.h:127
g728_decode_close
static av_cold int g728_decode_close(AVCodecContext *avctx)
Definition: g728dec.c:107
SAMPLES_PER_FRAME
#define SAMPLES_PER_FRAME
FFMAX
#define FFMAX(a, b)
Definition: macros.h:47
NFRSZ
#define NFRSZ
Definition: g728data.h:30
ff_celp_lp_synthesis_filterf
void ff_celp_lp_synthesis_filterf(float *out, const float *filter_coeffs, const float *in, int buffer_length, int filter_length)
LP synthesis filter.
Definition: celp_filters.c:85
NONRLG
#define NONRLG
Definition: g728data.h:32
ff_g728_decoder
const FFCodec ff_g728_decoder
Definition: g728dec.c:207
close
static av_cold void close(AVCodecParserContext *s)
Definition: apv_parser.c:135
get_bits
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:318
window
static SDL_Window * window
Definition: ffplay.c:361
FFCodec::p
AVCodec p
The public AVCodec.
Definition: codec_internal.h:131
AVCodecContext::ch_layout
AVChannelLayout ch_layout
Audio channel layout.
Definition: avcodec.h:1039
log10f
#define log10f(x)
Definition: libm.h:416
GetBitContext
Definition: get_bits.h:108
AVCodecContext::flags
int flags
AV_CODEC_FLAG_*.
Definition: avcodec.h:488
ff_thread_once
static int ff_thread_once(char *control, void(*routine)(void))
Definition: thread.h:205
FF_ARRAY_ELEMS
#define FF_ARRAY_ELEMS(a)
Definition: sinewin_tablegen.c:29
av_cold
#define av_cold
Definition: attributes.h:90
init_get_bits8
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:528
FF_CODEC_DECODE_CB
#define FF_CODEC_DECODE_CB(func)
Definition: codec_internal.h:341
s
#define s(width, name)
Definition: cbs_vp9.c:198
G728Context::alpha
float alpha
Definition: g728dec.c:82
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:201
NUPDATE
#define NUPDATE
Definition: g728data.h:33
decode.h
get_bits.h
NONR
#define NONR
Definition: g728data.h:31
LPCLG
#define LPCLG
Definition: g728data.h:29
g728data.h
gain_bw_tab
static const float gain_bw_tab[FFALIGN(10, 16)]
gain bandwidth broadening table
Definition: ra288.h:144
CODEC_LONG_NAME
#define CODEC_LONG_NAME(str)
Definition: codec_internal.h:326
g728_template.c
AV_ONCE_INIT
#define AV_ONCE_INIT
Definition: thread.h:203
LPCW
#define LPCW
Definition: g728dec.c:42
GOFF
#define GOFF
Definition: g728dec.c:43
celp_filters.h
av_clipf
av_clipf
Definition: af_crystalizer.c:122
AV_CODEC_ID_G728
@ AV_CODEC_ID_G728
Definition: codec_id.h:556
AVOnce
#define AVOnce
Definition: thread.h:202
float_dsp.h
g728_facv_f
static float g728_facv_f[FFALIGN(LPC, 16)]
Definition: g728dec.c:49
ff_scalarproduct_float_c
float ff_scalarproduct_float_c(const float *v1, const float *v2, int len)
Return the scalar product of two vectors of floats.
Definition: float_scalarproduct.c:24
AV_CODEC_CAP_CHANNEL_CONF
#define AV_CODEC_CAP_CHANNEL_CONF
Codec should fill in channel configuration and samplerate instead of container.
Definition: codec.h:91
f
f
Definition: af_crystalizer.c:122
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1635
init
int(* init)(AVBSFContext *ctx)
Definition: dts2pts.c:368
AV_CODEC_CAP_DR1
#define AV_CODEC_CAP_DR1
Codec uses get_buffer() or get_encode_buffer() for allocating buffers and supports custom allocators.
Definition: codec.h:52
AVPacket::size
int size
Definition: packet.h:536
powf
#define powf(x, y)
Definition: libm.h:52
AVChannelLayout
An AVChannelLayout holds information about the channel layout of audio data.
Definition: channel_layout.h:319
codec_internal.h
DECLARE_ALIGNED
#define DECLARE_ALIGNED(n, t, v)
Definition: mem_internal.h:104
AVFloatDSPContext::vector_fmul
void(* vector_fmul)(float *dst, const float *src0, const float *src1, int len)
Calculate the entry wise product of two vectors of floats and store the result in a vector of floats.
Definition: float_dsp.h:38
dst
uint8_t ptrdiff_t const uint8_t ptrdiff_t int intptr_t intptr_t int int16_t * dst
Definition: dsp.h:87
AVCodecContext::sample_fmt
enum AVSampleFormat sample_fmt
audio sample format
Definition: avcodec.h:1031
g728_wnr
static const uint16_t g728_wnr[NSBSZ]
Definition: g728data.h:39
AVFloatDSPContext
Definition: float_dsp.h:24
a
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
Definition: undefined.txt:41
do_hybrid_window
static void do_hybrid_window(void(*vector_fmul)(float *dst, const float *src0, const float *src1, int len), int order, int n, int non_rec, float *out, const float *hist, float *out2, const float *window)
Hybrid window filtering, see blocks 36 and 49 of the G.728 specification.
Definition: g728_template.c:40
g728_y_db
static float g728_y_db[128]
Definition: g728dec.c:46
g728_facv
static const uint16_t g728_facv[LPC]
Definition: g728data.h:62
g728_decode_init
static av_cold int g728_decode_init(AVCodecContext *avctx)
Definition: g728dec.c:85
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:256
compute_lpc_coefs
static int compute_lpc_coefs(const LPC_TYPE *autoc, int i, int max_order, LPC_TYPE *lpc, int lpc_stride, int fail, int normalize, LPC_TYPE *err_ptr)
Levinson-Durbin recursion.
Definition: lpc_functions.h:54
NSBGSZ
#define NSBGSZ
Definition: g728data.h:36
IDIM
#define IDIM
Definition: g728data.h:27
hybrid_window
static int hybrid_window(AVFloatDSPContext *fdsp, int order, int n, int non_rec, float *out, const float *hist, float *out2, const float *window)
Definition: g728dec.c:114
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:179
G728Context
Definition: g728dec.c:71
decode_frame
static void decode_frame(G728Context *s, GetBitContext *gb, float *dst)
Definition: g728dec.c:122
LPC
#define LPC
Definition: g728data.h:28
g728_gq_db
static float g728_gq_db[8]
Definition: g728dec.c:45
NSBSZ
#define NSBSZ
Definition: g728data.h:35
avcodec.h
ret
ret
Definition: filter_design.txt:187
frame
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
Definition: filter_design.txt:264
AVCodecContext
main external API structure.
Definition: avcodec.h:431
lpc_functions.h
av_channel_layout_uninit
void av_channel_layout_uninit(AVChannelLayout *channel_layout)
Free any allocated data in the channel layout and reset the channel count to 0.
Definition: channel_layout.c:442
G728Context::valid
int valid
Definition: g728dec.c:73
mem.h
AV_CODEC_FLAG_BITEXACT
#define AV_CODEC_FLAG_BITEXACT
Use only bitexact stuff (except (I)DCT).
Definition: avcodec.h:322
AV_CHANNEL_LAYOUT_MONO
#define AV_CHANNEL_LAYOUT_MONO
Definition: channel_layout.h:394
amptable
static const float amptable[8]
Definition: ra288.h:29
FFALIGN
#define FFALIGN(x, a)
Definition: macros.h:78
AVPacket
This structure stores compressed data.
Definition: packet.h:512
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:458
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
avpriv_float_dsp_alloc
av_cold AVFloatDSPContext * avpriv_float_dsp_alloc(int bit_exact)
Allocate a float DSP context.
Definition: float_dsp.c:135
g728_init_static_data
static av_cold void g728_init_static_data(void)
Definition: g728dec.c:51
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
g728_wnrg_r
static float g728_wnrg_r[FFALIGN(NSBGSZ, 16)]
Definition: g728dec.c:48
ra288.h
AV_SAMPLE_FMT_FLT
@ AV_SAMPLE_FMT_FLT
float
Definition: samplefmt.h:60
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