FFmpeg
dfpwmdec.c
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1 /*
2  * DFPWM decoder
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 decoder
26  */
27 
28 #include "libavutil/internal.h"
29 #include "avcodec.h"
30 #include "codec_id.h"
31 #include "codec_internal.h"
32 #include "decode.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 static void au_decompress(DFPWMState *state, int fs, int len,
42  uint8_t *outbuf, const uint8_t *inbuf)
43 {
44  unsigned d;
45  for (int i = 0; i < len; i++) {
46  // get bits
47  d = *(inbuf++);
48  for (int j = 0; j < 8; j++) {
49  int nq, lq, st, ns, ov;
50  // set target
51  int t = ((d&1) ? 127 : -128);
52  d >>= 1;
53 
54  // adjust charge
55  nq = state->q + ((state->s * (t-state->q) + 512)>>10);
56  if(nq == state->q && nq != t)
57  nq += (t == 127 ? 1 : -1);
58  lq = state->q;
59  state->q = nq;
60 
61  // adjust strength
62  st = (t != state->lt ? 0 : 1023);
63  ns = state->s;
64  if(ns != st)
65  ns += (st != 0 ? 1 : -1);
66  if(ns < 8) ns = 8;
67  state->s = ns;
68 
69  // FILTER: perform antijerk
70  ov = (t != state->lt ? (nq+lq+1)>>1 : nq);
71 
72  // FILTER: perform LPF
73  state->fq += ((fs*(ov-state->fq) + 0x80)>>8);
74  ov = state->fq;
75 
76  // output sample
77  *(outbuf++) = ov + 128;
78 
79  state->lt = t;
80  }
81  }
82 }
83 
85 {
87 
88  state->fq = 0;
89  state->q = 0;
90  state->s = 0;
91  state->lt = -128;
92 
93  ctx->sample_fmt = AV_SAMPLE_FMT_U8;
94  ctx->bits_per_raw_sample = 8;
95 
96  return 0;
97 }
98 
100  int *got_frame, struct AVPacket *packet)
101 {
103  int ret;
104 
105  if (packet->size * 8LL % ctx->ch_layout.nb_channels)
106  return AVERROR_PATCHWELCOME;
107 
108  frame->nb_samples = packet->size * 8LL / ctx->ch_layout.nb_channels;
109  if (frame->nb_samples <= 0) {
110  av_log(ctx, AV_LOG_ERROR, "invalid number of samples in packet\n");
111  return AVERROR_INVALIDDATA;
112  }
113 
114  if ((ret = ff_get_buffer(ctx, frame, 0)) < 0)
115  return ret;
116 
117  au_decompress(state, 140, packet->size, frame->data[0], packet->data);
118 
119  *got_frame = 1;
120  return packet->size;
121 }
122 
124  .p.name = "dfpwm",
125  CODEC_LONG_NAME("DFPWM1a audio"),
126  .p.type = AVMEDIA_TYPE_AUDIO,
127  .p.id = AV_CODEC_ID_DFPWM,
128  .priv_data_size = sizeof(DFPWMState),
129  .init = dfpwm_dec_init,
131  .p.capabilities = AV_CODEC_CAP_DR1,
132 };
state
static struct @335 state
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:325
AVPacket::data
uint8_t * data
Definition: packet.h:374
FFCodec
Definition: codec_internal.h:119
ff_dfpwm_decoder
const FFCodec ff_dfpwm_decoder
Definition: dfpwmdec.c:123
init
static int init
Definition: av_tx.c:47
FFCodec::p
AVCodec p
The public AVCodec.
Definition: codec_internal.h:123
DFPWMState::s
int s
Definition: dfpwmdec.c:35
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
av_cold
#define av_cold
Definition: attributes.h:90
codec_id.h
FF_CODEC_DECODE_CB
#define FF_CODEC_DECODE_CB(func)
Definition: codec_internal.h:279
au_decompress
static void au_decompress(DFPWMState *state, int fs, int len, uint8_t *outbuf, const uint8_t *inbuf)
Definition: dfpwmdec.c:41
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
ctx
AVFormatContext * ctx
Definition: movenc.c:48
decode.h
CODEC_LONG_NAME
#define CODEC_LONG_NAME(str)
Definition: codec_internal.h:264
AVERROR_PATCHWELCOME
#define AVERROR_PATCHWELCOME
Not yet implemented in FFmpeg, patches welcome.
Definition: error.h:64
fs
#define fs(width, name, subs,...)
Definition: cbs_vp9.c:258
dfpwm_dec_frame
static int dfpwm_dec_frame(struct AVCodecContext *ctx, AVFrame *frame, int *got_frame, struct AVPacket *packet)
Definition: dfpwmdec.c:99
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1450
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:375
codec_internal.h
ns
#define ns(max_value, name, subs,...)
Definition: cbs_av1.c:682
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
internal.h
AV_SAMPLE_FMT_U8
@ AV_SAMPLE_FMT_U8
unsigned 8 bits
Definition: samplefmt.h:57
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:211
len
int len
Definition: vorbis_enc_data.h:426
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
dfpwm_dec_init
static av_cold int dfpwm_dec_init(struct AVCodecContext *ctx)
Definition: dfpwmdec.c:84
AVCodecContext
main external API structure.
Definition: avcodec.h:398
DFPWMState
Definition: dfpwmdec.c:34
AVPacket
This structure stores compressed data.
Definition: packet.h:351
d
d
Definition: ffmpeg_filter.c:156
AV_CODEC_ID_DFPWM
@ AV_CODEC_ID_DFPWM
Definition: codec_id.h:529
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:27
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
AVFormatContext::priv_data
void * priv_data
Format private data.
Definition: avformat.h:1244