FFmpeg
libopencore-amr.c
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1 /*
2  * AMR Audio decoder stub
3  * Copyright (c) 2003 The FFmpeg project
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 "config_components.h"
23 
24 #include <inttypes.h>
25 
26 #include "libavutil/avstring.h"
28 #include "libavutil/common.h"
29 #include "libavutil/opt.h"
30 #include "avcodec.h"
31 #include "audio_frame_queue.h"
32 #include "codec_internal.h"
33 #include "encode.h"
34 #include "internal.h"
35 
36 #if CONFIG_LIBOPENCORE_AMRNB_DECODER || CONFIG_LIBOPENCORE_AMRWB_DECODER
37 static int amr_decode_fix_avctx(AVCodecContext *avctx)
38 {
39  const int is_amr_wb = 1 + (avctx->codec_id == AV_CODEC_ID_AMR_WB);
40 
41  if (!avctx->sample_rate)
42  avctx->sample_rate = 8000 * is_amr_wb;
43 
44  if (avctx->ch_layout.nb_channels > 1) {
45  avpriv_report_missing_feature(avctx, "multi-channel AMR");
46  return AVERROR_PATCHWELCOME;
47  }
48 
52  return 0;
53 }
54 #endif
55 
56 #if CONFIG_LIBOPENCORE_AMRNB
57 
58 #include <opencore-amrnb/interf_dec.h>
59 #include <opencore-amrnb/interf_enc.h>
60 
61 typedef struct AMRContext {
63  void *dec_state;
64  void *enc_state;
65  int enc_bitrate;
66  int enc_mode;
67  int enc_dtx;
68  int enc_last_frame;
69  AudioFrameQueue afq;
70 } AMRContext;
71 
72 #if CONFIG_LIBOPENCORE_AMRNB_DECODER
73 static av_cold int amr_nb_decode_init(AVCodecContext *avctx)
74 {
75  AMRContext *s = avctx->priv_data;
76  int ret;
77 
78  if ((ret = amr_decode_fix_avctx(avctx)) < 0)
79  return ret;
80 
81  s->dec_state = Decoder_Interface_init();
82  if (!s->dec_state) {
83  av_log(avctx, AV_LOG_ERROR, "Decoder_Interface_init error\n");
84  return -1;
85  }
86 
87  return 0;
88 }
89 
90 static av_cold int amr_nb_decode_close(AVCodecContext *avctx)
91 {
92  AMRContext *s = avctx->priv_data;
93 
94  Decoder_Interface_exit(s->dec_state);
95 
96  return 0;
97 }
98 
99 static int amr_nb_decode_frame(AVCodecContext *avctx, AVFrame *frame,
100  int *got_frame_ptr, AVPacket *avpkt)
101 {
102  const uint8_t *buf = avpkt->data;
103  int buf_size = avpkt->size;
104  AMRContext *s = avctx->priv_data;
105  static const uint8_t block_size[16] = { 12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0 };
106  enum Mode dec_mode;
107  int packet_size, ret;
108 
109  ff_dlog(avctx, "amr_decode_frame buf=%p buf_size=%d frame_count=%d!!\n",
110  buf, buf_size, avctx->frame_number);
111 
112  /* get output buffer */
113  frame->nb_samples = 160;
114  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
115  return ret;
116 
117  dec_mode = (buf[0] >> 3) & 0x000F;
118  packet_size = block_size[dec_mode] + 1;
119 
120  if (packet_size > buf_size) {
121  av_log(avctx, AV_LOG_ERROR, "AMR frame too short (%d, should be %d)\n",
122  buf_size, packet_size);
123  return AVERROR_INVALIDDATA;
124  }
125 
126  ff_dlog(avctx, "packet_size=%d buf= 0x%"PRIx8" %"PRIx8" %"PRIx8" %"PRIx8"\n",
127  packet_size, buf[0], buf[1], buf[2], buf[3]);
128  /* call decoder */
129  Decoder_Interface_Decode(s->dec_state, buf, (short *)frame->data[0], 0);
130 
131  *got_frame_ptr = 1;
132 
133  return packet_size;
134 }
135 
137  .p.name = "libopencore_amrnb",
138  .p.long_name = NULL_IF_CONFIG_SMALL("OpenCORE AMR-NB (Adaptive Multi-Rate Narrow-Band)"),
139  .p.type = AVMEDIA_TYPE_AUDIO,
140  .p.id = AV_CODEC_ID_AMR_NB,
141  .caps_internal = FF_CODEC_CAP_NOT_INIT_THREADSAFE,
142  .priv_data_size = sizeof(AMRContext),
143  .init = amr_nb_decode_init,
144  .close = amr_nb_decode_close,
145  FF_CODEC_DECODE_CB(amr_nb_decode_frame),
146  .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
147 };
148 #endif /* CONFIG_LIBOPENCORE_AMRNB_DECODER */
149 
150 #if CONFIG_LIBOPENCORE_AMRNB_ENCODER
151 /* Common code for fixed and float version*/
152 typedef struct AMR_bitrates {
153  int rate;
154  enum Mode mode;
155 } AMR_bitrates;
156 
157 /* Match desired bitrate */
158 static int get_bitrate_mode(int bitrate, void *log_ctx)
159 {
160  /* make the correspondence between bitrate and mode */
161  static const AMR_bitrates rates[] = {
162  { 4750, MR475 }, { 5150, MR515 }, { 5900, MR59 }, { 6700, MR67 },
163  { 7400, MR74 }, { 7950, MR795 }, { 10200, MR102 }, { 12200, MR122 }
164  };
165  int i, best = -1, min_diff = 0;
166  char log_buf[200];
167 
168  for (i = 0; i < 8; i++) {
169  if (rates[i].rate == bitrate)
170  return rates[i].mode;
171  if (best < 0 || abs(rates[i].rate - bitrate) < min_diff) {
172  best = i;
173  min_diff = abs(rates[i].rate - bitrate);
174  }
175  }
176  /* no bitrate matching exactly, log a warning */
177  snprintf(log_buf, sizeof(log_buf), "bitrate not supported: use one of ");
178  for (i = 0; i < 8; i++)
179  av_strlcatf(log_buf, sizeof(log_buf), "%.2fk, ", rates[i].rate / 1000.f);
180  av_strlcatf(log_buf, sizeof(log_buf), "using %.2fk", rates[best].rate / 1000.f);
181  av_log(log_ctx, AV_LOG_WARNING, "%s\n", log_buf);
182 
183  return best;
184 }
185 
186 static const AVOption options[] = {
187  { "dtx", "Allow DTX (generate comfort noise)", offsetof(AMRContext, enc_dtx), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_ENCODING_PARAM },
188  { NULL }
189 };
190 
191 static const AVClass amrnb_class = {
192  .class_name = "libopencore_amrnb",
193  .item_name = av_default_item_name,
194  .option = options,
195  .version = LIBAVUTIL_VERSION_INT,
196 };
197 
198 static av_cold int amr_nb_encode_init(AVCodecContext *avctx)
199 {
200  AMRContext *s = avctx->priv_data;
201 
202  if (avctx->sample_rate != 8000 && avctx->strict_std_compliance > FF_COMPLIANCE_UNOFFICIAL) {
203  av_log(avctx, AV_LOG_ERROR, "Only 8000Hz sample rate supported\n");
204  return AVERROR(ENOSYS);
205  }
206 
207  if (avctx->ch_layout.nb_channels != 1) {
208  av_log(avctx, AV_LOG_ERROR, "Only mono supported\n");
209  return AVERROR(ENOSYS);
210  }
211 
212  avctx->frame_size = 160;
213  avctx->initial_padding = 50;
214  ff_af_queue_init(avctx, &s->afq);
215 
216  s->enc_state = Encoder_Interface_init(s->enc_dtx);
217  if (!s->enc_state) {
218  av_log(avctx, AV_LOG_ERROR, "Encoder_Interface_init error\n");
219  return -1;
220  }
221 
222  s->enc_mode = get_bitrate_mode(avctx->bit_rate, avctx);
223  s->enc_bitrate = avctx->bit_rate;
224 
225  return 0;
226 }
227 
228 static av_cold int amr_nb_encode_close(AVCodecContext *avctx)
229 {
230  AMRContext *s = avctx->priv_data;
231 
232  Encoder_Interface_exit(s->enc_state);
233  ff_af_queue_close(&s->afq);
234  return 0;
235 }
236 
237 static int amr_nb_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
238  const AVFrame *frame, int *got_packet_ptr)
239 {
240  AMRContext *s = avctx->priv_data;
241  int written, ret;
242  int16_t *flush_buf = NULL;
243  const int16_t *samples = frame ? (const int16_t *)frame->data[0] : NULL;
244 
245  if (s->enc_bitrate != avctx->bit_rate) {
246  s->enc_mode = get_bitrate_mode(avctx->bit_rate, avctx);
247  s->enc_bitrate = avctx->bit_rate;
248  }
249 
250  if ((ret = ff_alloc_packet(avctx, avpkt, 32)) < 0)
251  return ret;
252 
253  if (frame) {
254  if (frame->nb_samples < avctx->frame_size) {
255  flush_buf = av_calloc(avctx->frame_size, sizeof(*flush_buf));
256  if (!flush_buf)
257  return AVERROR(ENOMEM);
258  memcpy(flush_buf, samples, frame->nb_samples * sizeof(*flush_buf));
259  samples = flush_buf;
260  if (frame->nb_samples < avctx->frame_size - avctx->initial_padding)
261  s->enc_last_frame = -1;
262  }
263  if ((ret = ff_af_queue_add(&s->afq, frame)) < 0) {
264  av_freep(&flush_buf);
265  return ret;
266  }
267  } else {
268  if (s->enc_last_frame < 0)
269  return 0;
270  flush_buf = av_calloc(avctx->frame_size, sizeof(*flush_buf));
271  if (!flush_buf)
272  return AVERROR(ENOMEM);
273  samples = flush_buf;
274  s->enc_last_frame = -1;
275  }
276 
277  written = Encoder_Interface_Encode(s->enc_state, s->enc_mode, samples,
278  avpkt->data, 0);
279  ff_dlog(avctx, "amr_nb_encode_frame encoded %u bytes, bitrate %u, first byte was %#02x\n",
280  written, s->enc_mode, avpkt->data[0]);
281 
282  /* Get the next frame pts/duration */
283  ff_af_queue_remove(&s->afq, avctx->frame_size, &avpkt->pts,
284  &avpkt->duration);
285 
286  avpkt->size = written;
287  *got_packet_ptr = 1;
288  av_freep(&flush_buf);
289  return 0;
290 }
291 
293  .p.name = "libopencore_amrnb",
294  .p.long_name = NULL_IF_CONFIG_SMALL("OpenCORE AMR-NB (Adaptive Multi-Rate Narrow-Band)"),
295  .p.type = AVMEDIA_TYPE_AUDIO,
296  .p.id = AV_CODEC_ID_AMR_NB,
297  .caps_internal = FF_CODEC_CAP_NOT_INIT_THREADSAFE,
298  .priv_data_size = sizeof(AMRContext),
299  .init = amr_nb_encode_init,
300  FF_CODEC_ENCODE_CB(amr_nb_encode_frame),
301  .close = amr_nb_encode_close,
303  .p.sample_fmts = (const enum AVSampleFormat[]){ AV_SAMPLE_FMT_S16,
305  .p.priv_class = &amrnb_class,
306 };
307 #endif /* CONFIG_LIBOPENCORE_AMRNB_ENCODER */
308 
309 #endif /* CONFIG_LIBOPENCORE_AMRNB */
310 
311 /* -----------AMR wideband ------------*/
312 #if CONFIG_LIBOPENCORE_AMRWB_DECODER
313 
314 #include <opencore-amrwb/dec_if.h>
315 #include <opencore-amrwb/if_rom.h>
316 
317 typedef struct AMRWBContext {
318  void *state;
319 } AMRWBContext;
320 
321 static av_cold int amr_wb_decode_init(AVCodecContext *avctx)
322 {
323  AMRWBContext *s = avctx->priv_data;
324  int ret;
325 
326  if ((ret = amr_decode_fix_avctx(avctx)) < 0)
327  return ret;
328 
329  s->state = D_IF_init();
330 
331  return 0;
332 }
333 
334 static int amr_wb_decode_frame(AVCodecContext *avctx, AVFrame *frame,
335  int *got_frame_ptr, AVPacket *avpkt)
336 {
337  const uint8_t *buf = avpkt->data;
338  int buf_size = avpkt->size;
339  AMRWBContext *s = avctx->priv_data;
340  int mode, ret;
341  int packet_size;
342  static const uint8_t block_size[16] = {18, 24, 33, 37, 41, 47, 51, 59, 61, 6, 6, 0, 0, 0, 1, 1};
343 
344  /* get output buffer */
345  frame->nb_samples = 320;
346  if ((ret = ff_get_buffer(avctx, frame, 0)) < 0)
347  return ret;
348 
349  mode = (buf[0] >> 3) & 0x000F;
350  packet_size = block_size[mode];
351 
352  if (packet_size > buf_size) {
353  av_log(avctx, AV_LOG_ERROR, "AMR frame too short (%d, should be %d)\n",
354  buf_size, packet_size + 1);
355  return AVERROR_INVALIDDATA;
356  }
357  if (!packet_size) {
358  av_log(avctx, AV_LOG_ERROR, "amr packet_size invalid\n");
359  return AVERROR_INVALIDDATA;
360  }
361 
362  D_IF_decode(s->state, buf, (short *)frame->data[0], _good_frame);
363 
364  *got_frame_ptr = 1;
365 
366  return packet_size;
367 }
368 
369 static int amr_wb_decode_close(AVCodecContext *avctx)
370 {
371  AMRWBContext *s = avctx->priv_data;
372 
373  D_IF_exit(s->state);
374  return 0;
375 }
376 
378  .p.name = "libopencore_amrwb",
379  .p.long_name = NULL_IF_CONFIG_SMALL("OpenCORE AMR-WB (Adaptive Multi-Rate Wide-Band)"),
380  .p.type = AVMEDIA_TYPE_AUDIO,
381  .p.id = AV_CODEC_ID_AMR_WB,
382  .p.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_CHANNEL_CONF,
383  .p.wrapper_name = "libopencore_amrwb",
384  .caps_internal = FF_CODEC_CAP_NOT_INIT_THREADSAFE,
385  .priv_data_size = sizeof(AMRWBContext),
386  .init = amr_wb_decode_init,
387  .close = amr_wb_decode_close,
388  FF_CODEC_DECODE_CB(amr_wb_decode_frame),
389 };
390 
391 #endif /* CONFIG_LIBOPENCORE_AMRWB_DECODER */
AVCodecContext::frame_size
int frame_size
Number of samples per channel in an audio frame.
Definition: avcodec.h:1035
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:186
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
ff_af_queue_remove
void ff_af_queue_remove(AudioFrameQueue *afq, int nb_samples, int64_t *pts, int64_t *duration)
Remove frame(s) from the queue.
Definition: audio_frame_queue.c:75
AVCodecContext::sample_rate
int sample_rate
samples per second
Definition: avcodec.h:1007
ff_af_queue_close
void ff_af_queue_close(AudioFrameQueue *afq)
Close AudioFrameQueue.
Definition: audio_frame_queue.c:36
ff_af_queue_init
av_cold void ff_af_queue_init(AVCodecContext *avctx, AudioFrameQueue *afq)
Initialize AudioFrameQueue.
Definition: audio_frame_queue.c:28
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:325
internal.h
AVPacket::data
uint8_t * data
Definition: packet.h:374
AVOption
AVOption.
Definition: opt.h:251
encode.h
AV_CHANNEL_LAYOUT_MONO
#define AV_CHANNEL_LAYOUT_MONO
Definition: channel_layout.h:353
AV_CODEC_ID_AMR_NB
@ AV_CODEC_ID_AMR_NB
Definition: codec_id.h:412
FF_CODEC_CAP_NOT_INIT_THREADSAFE
#define FF_CODEC_CAP_NOT_INIT_THREADSAFE
The codec is not known to be init-threadsafe (i.e.
Definition: codec_internal.h:33
FFCodec
Definition: codec_internal.h:118
AVPacket::duration
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: packet.h:392
AVChannelLayout::nb_channels
int nb_channels
Number of channels in this layout.
Definition: channel_layout.h:300
av_strlcatf
size_t av_strlcatf(char *dst, size_t size, const char *fmt,...)
Definition: avstring.c:104
FF_COMPLIANCE_UNOFFICIAL
#define FF_COMPLIANCE_UNOFFICIAL
Allow unofficial extensions.
Definition: avcodec.h:1313
AV_CODEC_ID_AMR_WB
@ AV_CODEC_ID_AMR_WB
Definition: codec_id.h:413
init
static int init
Definition: av_tx.c:47
FFCodec::p
AVCodec p
The public AVCodec.
Definition: codec_internal.h:122
AVCodecContext::ch_layout
AVChannelLayout ch_layout
Audio channel layout.
Definition: avcodec.h:2065
audio_frame_queue.h
AVCodecContext::initial_padding
int initial_padding
Audio only.
Definition: avcodec.h:1732
ff_libopencore_amrnb_decoder
const FFCodec ff_libopencore_amrnb_decoder
FF_CODEC_ENCODE_CB
#define FF_CODEC_ENCODE_CB(func)
Definition: codec_internal.h:269
ff_af_queue_add
int ff_af_queue_add(AudioFrameQueue *afq, const AVFrame *f)
Add a frame to the queue.
Definition: audio_frame_queue.c:44
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
Mode
Mode
Frame type (Table 1a in 3GPP TS 26.101)
Definition: amrnbdata.h:39
FF_CODEC_DECODE_CB
#define FF_CODEC_DECODE_CB(func)
Definition: codec_internal.h:260
s
#define s(width, name)
Definition: cbs_vp9.c:256
AV_OPT_FLAG_ENCODING_PARAM
#define AV_OPT_FLAG_ENCODING_PARAM
a generic parameter which can be set by the user for muxing or encoding
Definition: opt.h:281
ff_libopencore_amrnb_encoder
const FFCodec ff_libopencore_amrnb_encoder
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
AudioFrameQueue
Definition: audio_frame_queue.h:32
av_class
static const AVClass av_class
Definition: options.c:152
AMRWBContext::state
void * state
Definition: libvo-amrwbenc.c:38
AMRContext
Definition: amrnbdec.c:101
AV_OPT_FLAG_AUDIO_PARAM
#define AV_OPT_FLAG_AUDIO_PARAM
Definition: opt.h:283
AVCodecContext::codec_id
enum AVCodecID codec_id
Definition: avcodec.h:408
if
if(ret)
Definition: filter_design.txt:179
LIBAVUTIL_VERSION_INT
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:66
NULL
#define NULL
Definition: coverity.c:32
AVERROR_PATCHWELCOME
#define AVERROR_PATCHWELCOME
Not yet implemented in FFmpeg, patches welcome.
Definition: error.h:64
AVCodecContext::bit_rate
int64_t bit_rate
the average bitrate
Definition: avcodec.h:448
av_default_item_name
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:237
abs
#define abs(x)
Definition: cuda_runtime.h:35
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:630
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:109
ff_dlog
#define ff_dlog(a,...)
Definition: tableprint_vlc.h:28
options
const OptionDef options[]
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:1462
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
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
ff_libopencore_amrwb_decoder
const FFCodec ff_libopencore_amrwb_decoder
AVChannelLayout
An AVChannelLayout holds information about the channel layout of audio data.
Definition: channel_layout.h:290
codec_internal.h
AVCodecContext::sample_fmt
enum AVSampleFormat sample_fmt
audio sample format
Definition: avcodec.h:1023
AV_SAMPLE_FMT_NONE
@ AV_SAMPLE_FMT_NONE
Definition: samplefmt.h:56
avpriv_report_missing_feature
void avpriv_report_missing_feature(void *avc, const char *msg,...) av_printf_format(2
Log a generic warning message about a missing feature.
bitrate
int64_t bitrate
Definition: h264_levels.c:131
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:269
AVPacket::pts
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:367
common.h
AVSampleFormat
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:55
AV_SAMPLE_FMT_S16
@ AV_SAMPLE_FMT_S16
signed 16 bits
Definition: samplefmt.h:58
AVCodec::name
const char * name
Name of the codec implementation.
Definition: codec.h:211
av_calloc
void * av_calloc(size_t nmemb, size_t size)
Definition: mem.c:272
avcodec.h
ret
ret
Definition: filter_design.txt:187
AVClass::class_name
const char * class_name
The name of the class; usually it is the same name as the context structure type to which the AVClass...
Definition: log.h:71
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::strict_std_compliance
int strict_std_compliance
strictly follow the standard (MPEG-4, ...).
Definition: avcodec.h:1309
AVCodecContext
main external API structure.
Definition: avcodec.h:398
channel_layout.h
AMRWBContext
Definition: amrwbdec.c:48
rates
static const int rates[]
Definition: swresample.c:103
mode
mode
Definition: ebur128.h:83
AV_OPT_TYPE_INT
@ AV_OPT_TYPE_INT
Definition: opt.h:225
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
AVCodecContext::frame_number
int frame_number
Frame counter, set by libavcodec.
Definition: avcodec.h:1046
AVPacket
This structure stores compressed data.
Definition: packet.h:351
AVCodecContext::priv_data
void * priv_data
Definition: avcodec.h:425
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:34
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
avstring.h
AV_CODEC_CAP_SMALL_LAST_FRAME
#define AV_CODEC_CAP_SMALL_LAST_FRAME
Codec can be fed a final frame with a smaller size.
Definition: codec.h:87
snprintf
#define snprintf
Definition: snprintf.h:34
ff_alloc_packet
int ff_alloc_packet(AVCodecContext *avctx, AVPacket *avpkt, int64_t size)
Check AVPacket size and allocate data.
Definition: encode.c:35