FFmpeg
speedhqenc.c
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1 /*
2  * SpeedHQ encoder
3  * Copyright (c) 2000, 2001 Fabrice Bellard
4  * Copyright (c) 2003 Alex Beregszaszi
5  * Copyright (c) 2003-2004 Michael Niedermayer
6  * Copyright (c) 2020 FFmpeg
7  *
8  * This file is part of FFmpeg.
9  *
10  * FFmpeg is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU Lesser General Public
12  * License as published by the Free Software Foundation; either
13  * version 2.1 of the License, or (at your option) any later version.
14  *
15  * FFmpeg is distributed in the hope that it will be useful,
16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18  * Lesser General Public License for more details.
19  *
20  * You should have received a copy of the GNU Lesser General Public
21  * License along with FFmpeg; if not, write to the Free Software
22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23  */
24 
25 /**
26  * @file
27  * SpeedHQ encoder.
28  */
29 
30 #include "libavutil/pixdesc.h"
31 #include "libavutil/thread.h"
32 
33 #include "avcodec.h"
34 #include "mpeg12.h"
35 #include "mpegvideo.h"
36 #include "speedhqenc.h"
37 
38 extern RLTable ff_rl_speedhq;
40 
41 static uint16_t mpeg12_vlc_dc_lum_code_reversed[12];
43 
44 /* simple include everything table for dc, first byte is bits
45  * number next 3 are code */
46 static uint32_t speedhq_lum_dc_uni[512];
47 static uint32_t speedhq_chr_dc_uni[512];
48 
49 static uint8_t uni_speedhq_ac_vlc_len[64 * 64 * 2];
50 
51 static uint32_t reverse(uint32_t num, int bits)
52 {
53  return bitswap_32(num) >> (32 - bits);
54 }
55 
56 static void reverse_code(const uint16_t *code, const uint8_t *bits,
57  uint16_t *reversed_code, int num_entries)
58 {
59  for (int i = 0; i < num_entries; i++)
60  reversed_code[i] = reverse(code[i], bits[i]);
61 }
62 
64 {
65  /* Exactly the same as MPEG-2, except little-endian. */
69  12);
73  12);
74 
76 
77  /* build unified dc encoding tables */
78  for (int i = -255; i < 256; i++) {
79  int adiff, index;
80  int bits, code;
81  int diff = i;
82 
83  adiff = FFABS(diff);
84  if (diff < 0)
85  diff--;
86  index = av_log2(2 * adiff);
87 
91  speedhq_lum_dc_uni[i + 255] = bits + (code << 8);
92 
96  speedhq_chr_dc_uni[i + 255] = bits + (code << 8);
97  }
98 
100 }
101 
103 {
104  static AVOnce init_static_once = AV_ONCE_INIT;
105 
107 
108  if (s->width > 65500 || s->height > 65500) {
109  av_log(s, AV_LOG_ERROR, "SpeedHQ does not support resolutions above 65500x65500\n");
110  return AVERROR(EINVAL);
111  }
112 
113  s->min_qcoeff = -2048;
114  s->max_qcoeff = 2047;
115 
116  ff_thread_once(&init_static_once, speedhq_init_static_data);
117 
122 
123  switch (s->avctx->pix_fmt) {
124  case AV_PIX_FMT_YUV420P:
125  s->avctx->codec_tag = MKTAG('S','H','Q','0');
126  break;
127  case AV_PIX_FMT_YUV422P:
128  s->avctx->codec_tag = MKTAG('S','H','Q','2');
129  break;
130  case AV_PIX_FMT_YUV444P:
131  s->avctx->codec_tag = MKTAG('S','H','Q','4');
132  break;
133  default:
134  av_assert0(0);
135  }
136 
137  return 0;
138 }
139 
141 {
142  put_bits_le(&s->pb, 8, 100 - s->qscale * 2); /* FIXME why doubled */
143  put_bits_le(&s->pb, 24, 4); /* no second field */
144 
145  /* length of first slice, will be filled out later */
146  s->slice_start = 4;
147  put_bits_le(&s->pb, 24, 0);
148 }
149 
151 {
152  int slice_len;
153 
154  flush_put_bits_le(&s->pb);
155  slice_len = s->pb.buf_ptr - (s->pb.buf + s->slice_start);
156  AV_WL24(s->pb.buf + s->slice_start, slice_len);
157 
158  /* length of next slice, will be filled out later */
159  s->slice_start = s->pb.buf_ptr - s->pb.buf;
160  put_bits_le(&s->pb, 24, 0);
161 }
162 
163 static inline void encode_dc(PutBitContext *pb, int diff, int component)
164 {
165  unsigned int diff_u = diff + 255;
166  if (diff_u >= 511) {
167  int index;
168 
169  if (diff < 0) {
170  index = av_log2_16bit(-2 * diff);
171  diff--;
172  } else {
173  index = av_log2_16bit(2 * diff);
174  }
175  if (component == 0)
176  put_bits_le(pb,
177  ff_mpeg12_vlc_dc_lum_bits[index] + index,
179  (av_mod_uintp2(diff, index) << ff_mpeg12_vlc_dc_lum_bits[index]));
180  else
181  put_bits_le(pb,
182  ff_mpeg12_vlc_dc_chroma_bits[index] + index,
184  (av_mod_uintp2(diff, index) << ff_mpeg12_vlc_dc_chroma_bits[index]));
185  } else {
186  if (component == 0)
187  put_bits_le(pb,
188  speedhq_lum_dc_uni[diff + 255] & 0xFF,
189  speedhq_lum_dc_uni[diff + 255] >> 8);
190  else
191  put_bits_le(pb,
192  speedhq_chr_dc_uni[diff + 255] & 0xFF,
193  speedhq_chr_dc_uni[diff + 255] >> 8);
194  }
195 }
196 
197 static void encode_block(MpegEncContext *s, int16_t *block, int n)
198 {
199  int alevel, level, last_non_zero, dc, i, j, run, last_index, sign;
200  int code;
201  int component, val;
202 
203  /* DC coef */
204  component = (n <= 3 ? 0 : (n&1) + 1);
205  dc = block[0]; /* overflow is impossible */
206  val = s->last_dc[component] - dc; /* opposite of most codecs */
207  encode_dc(&s->pb, val, component);
208  s->last_dc[component] = dc;
209 
210  /* now quantify & encode AC coefs */
211  last_non_zero = 0;
212  last_index = s->block_last_index[n];
213 
214  for (i = 1; i <= last_index; i++) {
215  j = s->intra_scantable.permutated[i];
216  level = block[j];
217 
218  /* encode using VLC */
219  if (level != 0) {
220  run = i - last_non_zero - 1;
221 
222  alevel = level;
223  MASK_ABS(sign, alevel);
224  sign &= 1;
225 
226  if (alevel <= ff_rl_speedhq.max_level[0][run]) {
227  code = ff_rl_speedhq.index_run[0][run] + alevel - 1;
228  /* store the VLC & sign at once */
229  put_bits_le(&s->pb, ff_rl_speedhq.table_vlc[code][1] + 1,
230  ff_rl_speedhq.table_vlc[code][0] + (sign << ff_rl_speedhq.table_vlc[code][1]));
231  } else {
232  /* escape seems to be pretty rare <5% so I do not optimize it */
233  put_bits_le(&s->pb, ff_rl_speedhq.table_vlc[121][1], ff_rl_speedhq.table_vlc[121][0]);
234  /* escape: only clip in this case */
235  put_bits_le(&s->pb, 6, run);
236  put_bits_le(&s->pb, 12, level + 2048);
237  }
238  last_non_zero = i;
239  }
240  }
241  /* end of block */
242  put_bits_le(&s->pb, ff_rl_speedhq.table_vlc[122][1], ff_rl_speedhq.table_vlc[122][0]);
243 }
244 
246 {
247  int i;
248  for(i=0;i<6;i++) {
249  encode_block(s, block[i], i);
250  }
251  if (s->chroma_format == CHROMA_444) {
252  encode_block(s, block[8], 8);
253  encode_block(s, block[9], 9);
254 
255  encode_block(s, block[6], 6);
256  encode_block(s, block[7], 7);
257 
258  encode_block(s, block[10], 10);
259  encode_block(s, block[11], 11);
260  } else if (s->chroma_format == CHROMA_422) {
261  encode_block(s, block[6], 6);
262  encode_block(s, block[7], 7);
263  }
264 
265  s->i_tex_bits += get_bits_diff(s);
266 }
267 
268 static int ff_speedhq_mb_rows_in_slice(int slice_num, int mb_height)
269 {
270  return mb_height / 4 + (slice_num < (mb_height % 4));
271 }
272 
273 int ff_speedhq_mb_y_order_to_mb(int mb_y_order, int mb_height, int *first_in_slice)
274 {
275  int slice_num = 0;
276  while (mb_y_order >= ff_speedhq_mb_rows_in_slice(slice_num, mb_height)) {
277  mb_y_order -= ff_speedhq_mb_rows_in_slice(slice_num, mb_height);
278  slice_num++;
279  }
280  *first_in_slice = (mb_y_order == 0);
281  return mb_y_order * 4 + slice_num;
282 }
283 
284 #if CONFIG_SPEEDHQ_ENCODER
285 static const AVClass speedhq_class = {
286  .class_name = "speedhq encoder",
287  .item_name = av_default_item_name,
288  .option = ff_mpv_generic_options,
289  .version = LIBAVUTIL_VERSION_INT,
290 };
291 
293  .name = "speedhq",
294  .long_name = NULL_IF_CONFIG_SMALL("NewTek SpeedHQ"),
295  .type = AVMEDIA_TYPE_VIDEO,
296  .id = AV_CODEC_ID_SPEEDHQ,
297  .priv_data_size = sizeof(MpegEncContext),
299  .encode2 = ff_mpv_encode_picture,
300  .close = ff_mpv_encode_end,
301  .caps_internal = FF_CODEC_CAP_INIT_CLEANUP,
302  .pix_fmts = (const enum AVPixelFormat[]) {
305  },
306  .priv_class = &speedhq_class,
307 };
308 #endif
#define FF_CODEC_CAP_INIT_CLEANUP
The codec allows calling the close function for deallocation even if the init function returned a fai...
Definition: internal.h:49
#define MASK_ABS(mask, level)
Definition: mathops.h:155
static uint8_t uni_speedhq_ac_vlc_len[64 *64 *2]
Definition: speedhqenc.c:49
void ff_mpeg1_init_uni_ac_vlc(const RLTable *rl, uint8_t *uni_ac_vlc_len)
Definition: mpeg12enc.c:68
planar YUV 4:4:4, 24bpp, (1 Cr & Cb sample per 1x1 Y samples)
Definition: pixfmt.h:71
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:31
void ff_speedhq_encode_picture_header(MpegEncContext *s)
Definition: speedhqenc.c:140
static av_always_inline uint32_t bitswap_32(uint32_t x)
Definition: mathops.h:243
const unsigned char ff_mpeg12_vlc_dc_lum_bits[12]
Definition: mpeg12data.c:55
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:235
int av_log2(unsigned v)
Definition: intmath.c:26
void ff_speedhq_end_slice(MpegEncContext *s)
Definition: speedhqenc.c:150
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:746
int min_qcoeff
minimum encodable coefficient
Definition: mpegvideo.h:308
mpegvideo header.
uint8_t permutated[64]
Definition: idctdsp.h:33
const uint16_t ff_mpeg12_vlc_dc_lum_code[12]
Definition: mpeg12data.c:52
uint8_t run
Definition: svq3.c:203
uint8_t * intra_ac_vlc_length
Definition: mpegvideo.h:311
fg index
int av_log2_16bit(unsigned v)
Definition: intmath.c:31
AVCodec.
Definition: codec.h:197
int qscale
QP.
Definition: mpegvideo.h:204
RLTable.
Definition: rl.h:39
static void encode_block(MpegEncContext *s, int16_t *block, int n)
Definition: speedhqenc.c:197
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:72
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
#define AV_WL24(p, d)
Definition: intreadwrite.h:464
const AVOption ff_mpv_generic_options[]
Definition: mpegvideo_enc.c:87
The exact code depends on how similar the blocks are and how related they are to the block
uint8_t
#define av_cold
Definition: attributes.h:88
static uint32_t speedhq_lum_dc_uni[512]
Definition: speedhqenc.c:46
int8_t * max_level[2]
encoding & decoding
Definition: rl.h:46
static uint32_t reverse(uint32_t num, int bits)
Definition: speedhqenc.c:51
int max_qcoeff
maximum encodable coefficient
Definition: mpegvideo.h:309
#define AVOnce
Definition: thread.h:172
#define MAX_LEVEL
Definition: rl.h:36
#define CHROMA_444
Definition: mpegvideo.h:490
#define av_log(a,...)
static int get_bits_diff(MpegEncContext *s)
Definition: mpegvideo.h:777
int slice_context_count
number of used thread_contexts
Definition: mpegvideo.h:156
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
int last_dc[3]
last DC values for MPEG-1
Definition: mpegvideo.h:185
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:117
const uint16_t ff_mpeg12_vlc_dc_chroma_code[12]
Definition: mpeg12data.c:59
uint8_t * intra_chroma_ac_vlc_length
Definition: mpegvideo.h:313
uint8_t * buf
Definition: put_bits.h:54
const char * name
Name of the codec implementation.
Definition: codec.h:204
uint8_t bits
Definition: vp3data.h:141
RLTable ff_rl_speedhq
Definition: speedhq.c:137
planar YUV 4:2:2, 16bpp, (1 Cr & Cb sample per 2x1 Y samples)
Definition: pixfmt.h:70
static void flush_put_bits_le(PutBitContext *s)
Definition: put_bits.h:168
uint8_t * intra_ac_vlc_last_length
Definition: mpegvideo.h:312
static void put_bits_le(PutBitContext *s, int n, BitBuf value)
Definition: put_bits.h:262
#define CHROMA_422
Definition: mpegvideo.h:489
const uint16_t(* table_vlc)[2]
Definition: rl.h:42
SpeedHQ encoder.
static uint16_t mpeg12_vlc_dc_chroma_code_reversed[12]
Definition: speedhqenc.c:42
const unsigned char ff_mpeg12_vlc_dc_chroma_bits[12]
Definition: mpeg12data.c:62
static uint8_t speedhq_static_rl_table_store[2][2 *MAX_RUN+MAX_LEVEL+3]
Definition: speedhqenc.c:39
#define FFABS(a)
Absolute value, Note, INT_MIN / INT64_MIN result in undefined behavior as they are not representable ...
Definition: common.h:72
#define s(width, name)
Definition: cbs_vp9.c:257
int block_last_index[12]
last non zero coefficient in block
Definition: mpegvideo.h:86
static uint32_t speedhq_chr_dc_uni[512]
Definition: speedhqenc.c:47
av_cold void ff_rl_init(RLTable *rl, uint8_t static_store[2][2 *MAX_RUN+MAX_LEVEL+3])
Definition: rl.c:28
#define AV_ONCE_INIT
Definition: thread.h:173
AVCodec ff_speedhq_encoder
Libavcodec external API header.
static int ff_speedhq_mb_rows_in_slice(int slice_num, int mb_height)
Definition: speedhqenc.c:268
uint8_t * intra_chroma_ac_vlc_last_length
Definition: mpegvideo.h:314
Tag MUST be and< 10hcoeff half pel interpolation filter coefficients, hcoeff[0] are the 2 middle coefficients[1] are the next outer ones and so on, resulting in a filter like:...eff[2], hcoeff[1], hcoeff[0], hcoeff[0], hcoeff[1], hcoeff[2]...the sign of the coefficients is not explicitly stored but alternates after each coeff and coeff[0] is positive, so...,+,-,+,-,+,+,-,+,-,+,...hcoeff[0] is not explicitly stored but found by subtracting the sum of all stored coefficients with signs from 32 hcoeff[0]=32-hcoeff[1]-hcoeff[2]-...a good choice for hcoeff and htaps is htaps=6 hcoeff={40,-10, 2}an alternative which requires more computations at both encoder and decoder side and may or may not be better is htaps=8 hcoeff={42,-14, 6,-2}ref_frames minimum of the number of available reference frames and max_ref_frames for example the first frame after a key frame always has ref_frames=1spatial_decomposition_type wavelet type 0 is a 9/7 symmetric compact integer wavelet 1 is a 5/3 symmetric compact integer wavelet others are reserved stored as delta from last, last is reset to 0 if always_reset||keyframeqlog quality(logarithmic quantizer scale) stored as delta from last, last is reset to 0 if always_reset||keyframemv_scale stored as delta from last, last is reset to 0 if always_reset||keyframe FIXME check that everything works fine if this changes between framesqbias dequantization bias stored as delta from last, last is reset to 0 if always_reset||keyframeblock_max_depth maximum depth of the block tree stored as delta from last, last is reset to 0 if always_reset||keyframequant_table quantization tableHighlevel bitstream structure:==============================--------------------------------------------|Header|--------------------------------------------|------------------------------------|||Block0||||split?||||yes no||||.........intra?||||:Block01:yes no||||:Block02:.................||||:Block03::y DC::ref index:||||:Block04::cb DC::motion x:||||.........:cr DC::motion y:||||.................|||------------------------------------||------------------------------------|||Block1|||...|--------------------------------------------|------------------------------------|||Y subbands||Cb subbands||Cr subbands||||------||------||------|||||LL0||HL0||||LL0||HL0||||LL0||HL0|||||------||------||------||||------||------||------|||||LH0||HH0||||LH0||HH0||||LH0||HH0|||||------||------||------||||------||------||------|||||HL1||LH1||||HL1||LH1||||HL1||LH1|||||------||------||------||||------||------||------|||||HH1||HL2||||HH1||HL2||||HH1||HL2|||||...||...||...|||------------------------------------|--------------------------------------------Decoding process:=================------------|||Subbands|------------||||------------|Intra DC||||LL0 subband prediction------------|\Dequantization-------------------\||Reference frames|\IDWT|--------------|Motion\|||Frame 0||Frame 1||Compensation.OBMC v-------|--------------|--------------.\------> Frame n output Frame Frame<----------------------------------/|...|-------------------Range Coder:============Binary Range Coder:-------------------The implemented range coder is an adapted version based upon"Range encoding: an algorithm for removing redundancy from a digitised message."by G.N.N.Martin.The symbols encoded by the Snow range coder are bits(0|1).The associated probabilities are not fix but change depending on the symbol mix seen so far.bit seen|new state---------+-----------------------------------------------0|256-state_transition_table[256-old_state];1|state_transition_table[old_state];state_transition_table={0, 0, 0, 0, 0, 0, 0, 0, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 190, 191, 192, 194, 194, 195, 196, 197, 198, 199, 200, 201, 202, 202, 204, 205, 206, 207, 208, 209, 209, 210, 211, 212, 213, 215, 215, 216, 217, 218, 219, 220, 220, 222, 223, 224, 225, 226, 227, 227, 229, 229, 230, 231, 232, 234, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 248, 0, 0, 0, 0, 0, 0, 0};FIXME Range Coding of integers:-------------------------FIXME Neighboring Blocks:===================left and top are set to the respective blocks unless they are outside of the image in which case they are set to the Null block top-left is set to the top left block unless it is outside of the image in which case it is set to the left block if this block has no larger parent block or it is at the left side of its parent block and the top right block is not outside of the image then the top right block is used for top-right else the top-left block is used Null block y, cb, cr are 128 level, ref, mx and my are 0 Motion Vector Prediction:=========================1.the motion vectors of all the neighboring blocks are scaled to compensate for the difference of reference frames scaled_mv=(mv *(256 *(current_reference+1)/(mv.reference+1))+128)> the median of the scaled top and top right vectors is used as motion vector prediction the used motion vector is the sum of the predictor and(mvx_diff, mvy_diff)*mv_scale Intra DC Prediction block[y][x] dc[1]
Definition: snow.txt:400
ScanTable intra_scantable
Definition: mpegvideo.h:91
int height
picture size. must be a multiple of 16
Definition: mpegvideo.h:100
unsigned int codec_tag
fourcc (LSB first, so "ABCD" -> (&#39;D&#39;<<24) + (&#39;C&#39;<<16) + (&#39;B&#39;<<8) + &#39;A&#39;).
Definition: avcodec.h:561
static void encode_dc(PutBitContext *pb, int diff, int component)
Definition: speedhqenc.c:163
int ff_mpv_encode_init(AVCodecContext *avctx)
uint8_t * buf_ptr
Definition: put_bits.h:54
void ff_speedhq_encode_mb(MpegEncContext *s, int16_t block[12][64])
Definition: speedhqenc.c:245
Describe the class of an AVClass context structure.
Definition: log.h:67
uint8_t * index_run[2]
encoding only
Definition: rl.h:45
int ff_speedhq_mb_y_order_to_mb(int mb_y_order, int mb_height, int *first_in_slice)
Definition: speedhqenc.c:273
static enum AVPixelFormat pix_fmts[]
Definition: libkvazaar.c:303
static av_cold void speedhq_init_static_data(void)
Definition: speedhqenc.c:63
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
uint8_t level
Definition: svq3.c:204
MpegEncContext.
Definition: mpegvideo.h:81
#define MAX_RUN
Definition: rl.h:35
struct AVCodecContext * avctx
Definition: mpegvideo.h:98
PutBitContext pb
bit output
Definition: mpegvideo.h:151
planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
Definition: pixfmt.h:66
static void reverse_code(const uint16_t *code, const uint8_t *bits, uint16_t *reversed_code, int num_entries)
Definition: speedhqenc.c:56
int ff_mpv_encode_end(AVCodecContext *avctx)
static av_always_inline int diff(const uint32_t a, const uint32_t b)
static int ff_thread_once(char *control, void(*routine)(void))
Definition: thread.h:175
av_cold int ff_speedhq_encode_init(MpegEncContext *s)
Definition: speedhqenc.c:102
static uint16_t mpeg12_vlc_dc_lum_code_reversed[12]
Definition: speedhqenc.c:41
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
#define MKTAG(a, b, c, d)
Definition: common.h:478
int ff_mpv_encode_picture(AVCodecContext *avctx, AVPacket *pkt, const AVFrame *frame, int *got_packet)
AVPixelFormat
Pixel format.
Definition: pixfmt.h:64
static double val(void *priv, double ch)
Definition: aeval.c:76
int i
Definition: input.c:407
#define av_mod_uintp2
Definition: common.h:149