FFmpeg
apac.c
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1 /*
2  * APAC audio decoder
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "libavutil/audio_fifo.h"
22 #include "libavutil/internal.h"
23 #include "libavutil/intreadwrite.h"
24 #include "avcodec.h"
25 #include "codec_internal.h"
26 #include "decode.h"
27 #include "get_bits.h"
28 
29 typedef struct ChContext {
30  int have_code;
35  uint8_t block[32 * 2];
37 } ChContext;
38 
39 typedef struct APACContext {
41  int skip;
42 
43  int cur_ch;
45 
46  uint8_t *bitstream;
47  int64_t max_framesize;
50 } APACContext;
51 
52 static av_cold int apac_close(AVCodecContext *avctx)
53 {
54  APACContext *s = avctx->priv_data;
55 
56  av_freep(&s->bitstream);
57  s->bitstream_size = 0;
58 
59  for (int ch = 0; ch < 2; ch++) {
60  ChContext *c = &s->ch[ch];
61 
62  av_audio_fifo_free(c->samples);
63  }
64 
65  return 0;
66 }
67 
68 static av_cold int apac_init(AVCodecContext *avctx)
69 {
70  APACContext *s = avctx->priv_data;
71 
72  if (avctx->bits_per_coded_sample > 8)
74  else
76 
77  if (avctx->ch_layout.nb_channels < 1 ||
78  avctx->ch_layout.nb_channels > 2 ||
79  avctx->bits_per_coded_sample < 8 ||
80  avctx->bits_per_coded_sample > 16
81  )
82  return AVERROR_INVALIDDATA;
83 
84  for (int ch = 0; ch < avctx->ch_layout.nb_channels; ch++) {
85  ChContext *c = &s->ch[ch];
86 
87  c->bit_length = avctx->bits_per_coded_sample;
88  c->block_length = 8;
89  c->have_code = 0;
90  c->samples = av_audio_fifo_alloc(avctx->sample_fmt, 1, 1024);
91  if (!c->samples)
92  return AVERROR(ENOMEM);
93  }
94 
95  s->max_framesize = 1024;
96  s->bitstream = av_realloc_f(s->bitstream, s->max_framesize + AV_INPUT_BUFFER_PADDING_SIZE, sizeof(*s->bitstream));
97  if (!s->bitstream)
98  return AVERROR(ENOMEM);
99 
100  return 0;
101 }
102 
104 {
105  if (get_bits1(gb)) {
106  int code = get_bits(gb, 2);
107 
108  switch (code) {
109  case 0:
110  c->bit_length--;
111  break;
112  case 1:
113  c->bit_length++;
114  break;
115  case 2:
116  c->bit_length = get_bits(gb, 5);
117  break;
118  case 3:
119  c->block_length = get_bits(gb, 4);
120  return 1;
121  }
122  }
123 
124  return 0;
125 }
126 
128  int *got_frame_ptr, AVPacket *pkt)
129 {
130  APACContext *s = avctx->priv_data;
131  GetBitContext *gb = &s->gb;
132  int ret, n, buf_size, input_buf_size;
133  const uint8_t *buf;
134  int nb_samples;
135 
136  if (!pkt->size && s->bitstream_size <= 0) {
137  *got_frame_ptr = 0;
138  return 0;
139  }
140 
141  buf_size = pkt->size;
142  input_buf_size = buf_size;
143 
144  if (s->bitstream_index > 0 && s->bitstream_size > 0) {
145  memmove(s->bitstream, &s->bitstream[s->bitstream_index], s->bitstream_size);
146  s->bitstream_index = 0;
147  }
148 
149  if (s->bitstream_index + s->bitstream_size + buf_size > s->max_framesize) {
150  s->bitstream = av_realloc_f(s->bitstream, s->bitstream_index +
151  s->bitstream_size +
152  buf_size + AV_INPUT_BUFFER_PADDING_SIZE,
153  sizeof(*s->bitstream));
154  if (!s->bitstream)
155  return AVERROR(ENOMEM);
156  s->max_framesize = s->bitstream_index + s->bitstream_size + buf_size;
157  }
158  if (pkt->data)
159  memcpy(&s->bitstream[s->bitstream_index + s->bitstream_size], pkt->data, buf_size);
160  buf = &s->bitstream[s->bitstream_index];
161  buf_size += s->bitstream_size;
162  s->bitstream_size = buf_size;
163 
164  frame->nb_samples = s->bitstream_size * 16 * 8;
165  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
166  return ret;
167 
168  if ((ret = init_get_bits8(gb, buf, buf_size)) < 0)
169  return ret;
170 
171  skip_bits(gb, s->skip);
172  s->skip = 0;
173 
174  while (get_bits_left(gb) > 0) {
175  for (int ch = s->cur_ch; ch < avctx->ch_layout.nb_channels; ch++) {
176  ChContext *c = &s->ch[ch];
177  int16_t *dst16 = (int16_t *)c->block;
178  uint8_t *dst8 = (uint8_t *)c->block;
179  void *samples[4];
180 
181  samples[0] = &c->block[0];
182  if (get_bits_left(gb) < 16 && pkt->size) {
183  s->cur_ch = ch;
184  goto end;
185  }
186 
187  if (!c->have_code && get_code(c, gb))
188  get_code(c, gb);
189  c->have_code = 0;
190 
191  if (c->block_length <= 0)
192  continue;
193 
194  if (c->bit_length < 0 ||
195  c->bit_length > 17) {
196  c->bit_length = avctx->bits_per_coded_sample;
197  s->bitstream_index = 0;
198  s->bitstream_size = 0;
199  return AVERROR_INVALIDDATA;
200  }
201 
202  if (get_bits_left(gb) < c->block_length * c->bit_length) {
203  if (pkt->size) {
204  c->have_code = 1;
205  s->cur_ch = ch;
206  goto end;
207  } else {
208  break;
209  }
210  }
211 
212  for (int i = 0; i < c->block_length; i++) {
213  int val = get_bits_long(gb, c->bit_length);
214  unsigned delta = (val & 1) ? ~(val >> 1) : (val >> 1);
215  int sample;
216 
217  delta += c->last_delta;
218  sample = c->last_sample + delta;
219  c->last_delta = delta;
220  c->last_sample = sample;
221 
222  switch (avctx->sample_fmt) {
223  case AV_SAMPLE_FMT_S16P:
224  dst16[i] = sample;
225  break;
226  case AV_SAMPLE_FMT_U8P:
227  dst8[i] = sample;
228  break;
229  }
230  }
231 
232  av_audio_fifo_write(c->samples, samples, c->block_length);
233  }
234 
235  s->cur_ch = 0;
236  }
237 end:
238  nb_samples = frame->nb_samples;
239  for (int ch = 0; ch < avctx->ch_layout.nb_channels; ch++)
240  nb_samples = FFMIN(av_audio_fifo_size(s->ch[ch].samples), nb_samples);
241 
242  frame->nb_samples = nb_samples;
243  for (int ch = 0; ch < avctx->ch_layout.nb_channels; ch++) {
244  void *samples[1] = { frame->extended_data[ch] };
245  av_audio_fifo_read(s->ch[ch].samples, samples, nb_samples);
246  }
247 
248  s->skip = get_bits_count(gb) - 8 * (get_bits_count(gb) / 8);
249  n = get_bits_count(gb) / 8;
250 
251  if (nb_samples > 0 || pkt->size)
252  *got_frame_ptr = 1;
253 
254  if (s->bitstream_size > 0) {
255  s->bitstream_index += n;
256  s->bitstream_size -= n;
257  return input_buf_size;
258  }
259  return n;
260 }
261 
263  .p.name = "apac",
264  CODEC_LONG_NAME("Marian's A-pac audio"),
265  .p.type = AVMEDIA_TYPE_AUDIO,
266  .p.id = AV_CODEC_ID_APAC,
267  .priv_data_size = sizeof(APACContext),
268  .init = apac_init,
270  .close = apac_close,
271  .p.capabilities = AV_CODEC_CAP_DELAY |
274  .caps_internal = FF_CODEC_CAP_INIT_CLEANUP,
275  .p.sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_U8P,
278 };
AV_CODEC_ID_APAC
@ AV_CODEC_ID_APAC
Definition: codec_id.h:537
av_audio_fifo_free
void av_audio_fifo_free(AVAudioFifo *af)
Free an AVAudioFifo.
Definition: audio_fifo.c:48
FF_CODEC_CAP_INIT_CLEANUP
#define FF_CODEC_CAP_INIT_CLEANUP
The codec allows calling the close function for deallocation even if the init function returned a fai...
Definition: codec_internal.h:42
get_bits_left
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:664
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
get_bits_long
static unsigned int get_bits_long(GetBitContext *s, int n)
Read 0-32 bits.
Definition: get_bits.h:411
get_bits_count
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:256
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:330
AVPacket::data
uint8_t * data
Definition: packet.h:374
FFCodec
Definition: codec_internal.h:127
APACContext::bitstream_size
int bitstream_size
Definition: apac.c:48
AVChannelLayout::nb_channels
int nb_channels
Number of channels in this layout.
Definition: channel_layout.h:311
skip_bits
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:371
get_bits
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:325
AVAudioFifo
Context for an Audio FIFO Buffer.
Definition: audio_fifo.c:37
FFCodec::p
AVCodec p
The public AVCodec.
Definition: codec_internal.h:131
AVCodecContext::ch_layout
AVChannelLayout ch_layout
Audio channel layout.
Definition: avcodec.h:2092
GetBitContext
Definition: get_bits.h:107
APACContext::ch
ChContext ch[2]
Definition: apac.c:44
val
static double val(void *priv, double ch)
Definition: aeval.c:77
get_code
static int get_code(ChContext *c, GetBitContext *gb)
Definition: apac.c:103
pkt
AVPacket * pkt
Definition: movenc.c:59
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:524
APACContext::gb
GetBitContext gb
Definition: apac.c:40
FF_CODEC_DECODE_CB
#define FF_CODEC_DECODE_CB(func)
Definition: codec_internal.h:306
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:256
av_audio_fifo_write
int av_audio_fifo_write(AVAudioFifo *af, void **data, int nb_samples)
Write data to an AVAudioFifo.
Definition: audio_fifo.c:119
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
init
int(* init)(AVBSFContext *ctx)
Definition: dts2pts_bsf.c:365
decode.h
get_bits.h
APACContext::cur_ch
int cur_ch
Definition: apac.c:43
CODEC_LONG_NAME
#define CODEC_LONG_NAME(str)
Definition: codec_internal.h:272
ChContext::block
uint8_t block[32 *2]
Definition: apac.c:35
av_realloc_f
#define av_realloc_f(p, o, n)
Definition: tableprint_vlc.h:32
ChContext
Definition: apac.c:29
av_audio_fifo_alloc
AVAudioFifo * av_audio_fifo_alloc(enum AVSampleFormat sample_fmt, int channels, int nb_samples)
Allocate an AVAudioFifo.
Definition: audio_fifo.c:62
get_bits1
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:378
apac_init
static av_cold int apac_init(AVCodecContext *avctx)
Definition: apac.c:68
ChContext::last_sample
int last_sample
Definition: apac.c:31
ChContext::have_code
int have_code
Definition: apac.c:30
c
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
APACContext::skip
int skip
Definition: apac.c:41
ff_get_buffer
int ff_get_buffer(AVCodecContext *avctx, AVFrame *frame, int flags)
Get a buffer for a frame.
Definition: decode.c:1461
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
AV_SAMPLE_FMT_U8P
@ AV_SAMPLE_FMT_U8P
unsigned 8 bits, planar
Definition: samplefmt.h:63
codec_internal.h
APACContext::bitstream_index
int bitstream_index
Definition: apac.c:49
AVCodecContext::sample_fmt
enum AVSampleFormat sample_fmt
audio sample format
Definition: avcodec.h:1056
AV_SAMPLE_FMT_NONE
@ AV_SAMPLE_FMT_NONE
Definition: samplefmt.h:56
sample
#define sample
Definition: flacdsp_template.c:44
ff_apac_decoder
const FFCodec ff_apac_decoder
Definition: apac.c:262
av_audio_fifo_size
int av_audio_fifo_size(AVAudioFifo *af)
Get the current number of samples in the AVAudioFifo available for reading.
Definition: audio_fifo.c:221
AV_SAMPLE_FMT_S16P
@ AV_SAMPLE_FMT_S16P
signed 16 bits, planar
Definition: samplefmt.h:64
AVCodecContext::bits_per_coded_sample
int bits_per_coded_sample
bits per sample/pixel from the demuxer (needed for huffyuv).
Definition: avcodec.h:1477
av_audio_fifo_read
int av_audio_fifo_read(AVAudioFifo *af, void **data, int nb_samples)
Read data from an AVAudioFifo.
Definition: audio_fifo.c:174
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
code
and forward the test the status of outputs and forward it to the corresponding return FFERROR_NOT_READY If the filters stores internally one or a few frame for some it can consider them to be part of the FIFO and delay acknowledging a status change accordingly Example code
Definition: filter_design.txt:178
internal.h
APACContext::max_framesize
int64_t max_framesize
Definition: apac.c:47
AVSampleFormat
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:55
APACContext
Definition: apac.c:39
delta
float delta
Definition: vorbis_enc_data.h:430
FFMIN
#define FFMIN(a, b)
Definition: macros.h:49
audio_fifo.h
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:211
ChContext::block_length
int block_length
Definition: apac.c:34
avcodec.h
ChContext::samples
AVAudioFifo * samples
Definition: apac.c:36
ChContext::bit_length
int bit_length
Definition: apac.c:33
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
AV_INPUT_BUFFER_PADDING_SIZE
#define AV_INPUT_BUFFER_PADDING_SIZE
Definition: defs.h:40
AVCodecContext
main external API structure.
Definition: avcodec.h:431
apac_close
static av_cold int apac_close(AVCodecContext *avctx)
Definition: apac.c:52
AV_CODEC_CAP_DELAY
#define AV_CODEC_CAP_DELAY
Encoder or decoder requires flushing with NULL input at the end in order to give the complete and cor...
Definition: codec.h:82
samples
Filter the word “frame” indicates either a video frame or a group of audio samples
Definition: filter_design.txt:8
AV_CODEC_CAP_SUBFRAMES
#define AV_CODEC_CAP_SUBFRAMES
Codec can output multiple frames per AVPacket Normally demuxers return one frame at a time,...
Definition: codec.h:100
APACContext::bitstream
uint8_t * bitstream
Definition: apac.c:46
AVPacket
This structure stores compressed data.
Definition: packet.h:351
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:458
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:34
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
ChContext::last_delta
int last_delta
Definition: apac.c:32
apac_decode
static int apac_decode(AVCodecContext *avctx, AVFrame *frame, int *got_frame_ptr, AVPacket *pkt)
Definition: apac.c:127