FFmpeg
dfpwmenc.c
Go to the documentation of this file.
1 /*
2  * DFPWM encoder
3  * Copyright (c) 2022 Jack Bruienne
4  * Copyright (c) 2012, 2016 Ben "GreaseMonkey" Russell
5  *
6  * This file is part of FFmpeg.
7  *
8  * FFmpeg is free software; you can redistribute it and/or
9  * modify it under the terms of the GNU Lesser General Public
10  * License as published by the Free Software Foundation; either
11  * version 2.1 of the License, or (at your option) any later version.
12  *
13  * FFmpeg is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16  * Lesser General Public License for more details.
17  *
18  * You should have received a copy of the GNU Lesser General Public
19  * License along with FFmpeg; if not, write to the Free Software
20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21  */
22 
23 /**
24  * @file
25  * DFPWM1a encoder
26  */
27 
28 #include "libavutil/internal.h"
29 #include "avcodec.h"
30 #include "codec_id.h"
31 #include "codec_internal.h"
32 #include "encode.h"
33 
34 typedef struct {
35  int fq, q, s, lt;
36 } DFPWMState;
37 
38 // DFPWM codec from https://github.com/ChenThread/dfpwm/blob/master/1a/
39 // Licensed in the public domain
40 
41 // note, len denotes how many compressed bytes there are (uncompressed bytes / 8).
42 static void au_compress(DFPWMState *state, int len, uint8_t *outbuf, const uint8_t *inbuf)
43 {
44  unsigned d = 0;
45  for (int i = 0; i < len; i++) {
46  for (int j = 0; j < 8; j++) {
47  int nq, st, ns;
48  // get sample
49  int v = *(inbuf++) - 128;
50  // set bit / target
51  int t = (v > state->q || (v == state->q && v == 127) ? 127 : -128);
52  d >>= 1;
53  if(t > 0)
54  d |= 0x80;
55 
56  // adjust charge
57  nq = state->q + ((state->s * (t-state->q) + 512)>>10);
58  if(nq == state->q && nq != t)
59  nq += (t == 127 ? 1 : -1);
60  state->q = nq;
61 
62  // adjust strength
63  st = (t != state->lt ? 0 : 1023);
64  ns = state->s;
65  if(ns != st)
66  ns += (st != 0 ? 1 : -1);
67  if(ns < 8) ns = 8;
68  state->s = ns;
69 
70  state->lt = t;
71  }
72 
73  // output bits
74  *(outbuf++) = d;
75  }
76 }
77 
79 {
81 
82  state->fq = 0;
83  state->q = 0;
84  state->s = 0;
85  state->lt = -128;
86 
87  ctx->bits_per_coded_sample = 1;
88 
89  return 0;
90 }
91 
92 static int dfpwm_enc_frame(struct AVCodecContext *ctx, struct AVPacket *packet,
93  const struct AVFrame *frame, int *got_packet)
94 {
96  int size = frame->nb_samples * frame->ch_layout.nb_channels / 8 + (frame->nb_samples % 8 > 0 ? 1 : 0);
98 
99  if (ret) {
100  *got_packet = 0;
101  return ret;
102  }
103 
104  au_compress(state, size, packet->data, frame->data[0]);
105 
106  *got_packet = 1;
107  return 0;
108 }
109 
111  .p.name = "dfpwm",
112  CODEC_LONG_NAME("DFPWM1a audio"),
113  .p.type = AVMEDIA_TYPE_AUDIO,
114  .p.id = AV_CODEC_ID_DFPWM,
115  .priv_data_size = sizeof(DFPWMState),
116  .init = dfpwm_enc_init,
118  .p.sample_fmts = (const enum AVSampleFormat[]){AV_SAMPLE_FMT_U8, AV_SAMPLE_FMT_NONE},
121 };
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:340
encode.h
au_compress
static void au_compress(DFPWMState *state, int len, uint8_t *outbuf, const uint8_t *inbuf)
Definition: dfpwmenc.c:42
FFCodec
Definition: codec_internal.h:127
AVChannelLayout::nb_channels
int nb_channels
Number of channels in this layout.
Definition: channel_layout.h:323
AVFrame::data
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:361
FFCodec::p
AVCodec p
The public AVCodec.
Definition: codec_internal.h:131
state
static struct @377 state
dfpwm_enc_frame
static int dfpwm_enc_frame(struct AVCodecContext *ctx, struct AVPacket *packet, const struct AVFrame *frame, int *got_packet)
Definition: dfpwmenc.c:92
AVFrame::ch_layout
AVChannelLayout ch_layout
Channel layout of the audio data.
Definition: frame.h:802
FF_CODEC_ENCODE_CB
#define FF_CODEC_ENCODE_CB(func)
Definition: codec_internal.h:315
av_cold
#define av_cold
Definition: attributes.h:90
codec_id.h
s
#define s(width, name)
Definition: cbs_vp9.c:198
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE
#define AV_CODEC_CAP_ENCODER_REORDERED_OPAQUE
This encoder can reorder user opaque values from input AVFrames and return them with corresponding ou...
Definition: codec.h:159
ctx
AVFormatContext * ctx
Definition: movenc.c:48
CODEC_LONG_NAME
#define CODEC_LONG_NAME(str)
Definition: codec_internal.h:272
frame
static AVFrame * frame
Definition: demux_decode.c:54
dfpwm_enc_init
static av_cold int dfpwm_enc_init(struct AVCodecContext *ctx)
Definition: dfpwmenc.c:78
AV_CODEC_CAP_VARIABLE_FRAME_SIZE
#define AV_CODEC_CAP_VARIABLE_FRAME_SIZE
Audio encoder supports receiving a different number of samples in each call.
Definition: codec.h:128
init
int(* init)(AVBSFContext *ctx)
Definition: dts2pts.c:365
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
codec_internal.h
AV_SAMPLE_FMT_NONE
@ AV_SAMPLE_FMT_NONE
Definition: samplefmt.h:56
size
int size
Definition: twinvq_data.h:10344
ns
#define ns(max_value, name, subs,...)
Definition: cbs_av1.c:608
AVFrame::nb_samples
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:420
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:255
internal.h
AV_SAMPLE_FMT_U8
@ AV_SAMPLE_FMT_U8
unsigned 8 bits
Definition: samplefmt.h:57
AVSampleFormat
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:55
packet
enum AVPacketSideDataType packet
Definition: decode.c:1425
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:194
len
int len
Definition: vorbis_enc_data.h:426
avcodec.h
ret
ret
Definition: filter_design.txt:187
AVCodecContext
main external API structure.
Definition: avcodec.h:445
ff_get_encode_buffer
int ff_get_encode_buffer(AVCodecContext *avctx, AVPacket *avpkt, int64_t size, int flags)
Get a buffer for a packet.
Definition: encode.c:105
ff_dfpwm_encoder
const FFCodec ff_dfpwm_encoder
Definition: dfpwmenc.c:110
DFPWMState
Definition: dfpwmdec.c:34
AVPacket
This structure stores compressed data.
Definition: packet.h:499
d
d
Definition: ffmpeg_filter.c:424
AV_CODEC_ID_DFPWM
@ AV_CODEC_ID_DFPWM
Definition: codec_id.h:539
AVFormatContext::priv_data
void * priv_data
Format private data.
Definition: avformat.h:1391