FFmpeg
v4l2_buffers.c
Go to the documentation of this file.
1 /*
2  * V4L2 buffer helper functions.
3  *
4  * Copyright (C) 2017 Alexis Ballier <aballier@gentoo.org>
5  * Copyright (C) 2017 Jorge Ramirez <jorge.ramirez-ortiz@linaro.org>
6  *
7  * This file is part of FFmpeg.
8  *
9  * FFmpeg is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2.1 of the License, or (at your option) any later version.
13  *
14  * FFmpeg is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with FFmpeg; if not, write to the Free Software
21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22  */
23 
24 #include <linux/videodev2.h>
25 #include <sys/ioctl.h>
26 #include <sys/mman.h>
27 #include <unistd.h>
28 #include <fcntl.h>
29 #include <poll.h>
30 #include "libavcodec/avcodec.h"
31 #include "libavcodec/internal.h"
32 #include "libavutil/pixdesc.h"
33 #include "v4l2_context.h"
34 #include "v4l2_buffers.h"
35 #include "v4l2_m2m.h"
36 
37 #define USEC_PER_SEC 1000000
38 static AVRational v4l2_timebase = { 1, USEC_PER_SEC };
39 
40 static inline V4L2m2mContext *buf_to_m2mctx(V4L2Buffer *buf)
41 {
42  return V4L2_TYPE_IS_OUTPUT(buf->context->type) ?
43  container_of(buf->context, V4L2m2mContext, output) :
44  container_of(buf->context, V4L2m2mContext, capture);
45 }
46 
47 static inline AVCodecContext *logger(V4L2Buffer *buf)
48 {
49  return buf_to_m2mctx(buf)->avctx;
50 }
51 
52 static inline AVRational v4l2_get_timebase(V4L2Buffer *avbuf)
53 {
54  V4L2m2mContext *s = buf_to_m2mctx(avbuf);
55 
56  if (s->avctx->pkt_timebase.num)
57  return s->avctx->pkt_timebase;
58  return s->avctx->time_base;
59 }
60 
61 static inline void v4l2_set_pts(V4L2Buffer *out, int64_t pts)
62 {
63  int64_t v4l2_pts;
64 
65  if (pts == AV_NOPTS_VALUE)
66  pts = 0;
67 
68  /* convert pts to v4l2 timebase */
69  v4l2_pts = av_rescale_q(pts, v4l2_get_timebase(out), v4l2_timebase);
70  out->buf.timestamp.tv_usec = v4l2_pts % USEC_PER_SEC;
71  out->buf.timestamp.tv_sec = v4l2_pts / USEC_PER_SEC;
72 }
73 
74 static inline int64_t v4l2_get_pts(V4L2Buffer *avbuf)
75 {
76  int64_t v4l2_pts;
77 
78  /* convert pts back to encoder timebase */
79  v4l2_pts = (int64_t)avbuf->buf.timestamp.tv_sec * USEC_PER_SEC +
80  avbuf->buf.timestamp.tv_usec;
81 
82  return av_rescale_q(v4l2_pts, v4l2_timebase, v4l2_get_timebase(avbuf));
83 }
84 
85 static enum AVColorPrimaries v4l2_get_color_primaries(V4L2Buffer *buf)
86 {
87  enum v4l2_ycbcr_encoding ycbcr;
88  enum v4l2_colorspace cs;
89 
90  cs = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
91  buf->context->format.fmt.pix_mp.colorspace :
92  buf->context->format.fmt.pix.colorspace;
93 
94  ycbcr = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
95  buf->context->format.fmt.pix_mp.ycbcr_enc:
96  buf->context->format.fmt.pix.ycbcr_enc;
97 
98  switch(ycbcr) {
99  case V4L2_YCBCR_ENC_XV709:
100  case V4L2_YCBCR_ENC_709: return AVCOL_PRI_BT709;
101  case V4L2_YCBCR_ENC_XV601:
102  case V4L2_YCBCR_ENC_601:return AVCOL_PRI_BT470M;
103  default:
104  break;
105  }
106 
107  switch(cs) {
108  case V4L2_COLORSPACE_470_SYSTEM_BG: return AVCOL_PRI_BT470BG;
109  case V4L2_COLORSPACE_SMPTE170M: return AVCOL_PRI_SMPTE170M;
110  case V4L2_COLORSPACE_SMPTE240M: return AVCOL_PRI_SMPTE240M;
111  case V4L2_COLORSPACE_BT2020: return AVCOL_PRI_BT2020;
112  default:
113  break;
114  }
115 
116  return AVCOL_PRI_UNSPECIFIED;
117 }
118 
119 static enum AVColorRange v4l2_get_color_range(V4L2Buffer *buf)
120 {
121  enum v4l2_quantization qt;
122 
123  qt = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
124  buf->context->format.fmt.pix_mp.quantization :
125  buf->context->format.fmt.pix.quantization;
126 
127  switch (qt) {
128  case V4L2_QUANTIZATION_LIM_RANGE: return AVCOL_RANGE_MPEG;
129  case V4L2_QUANTIZATION_FULL_RANGE: return AVCOL_RANGE_JPEG;
130  default:
131  break;
132  }
133 
134  return AVCOL_RANGE_UNSPECIFIED;
135 }
136 
137 static enum AVColorSpace v4l2_get_color_space(V4L2Buffer *buf)
138 {
139  enum v4l2_ycbcr_encoding ycbcr;
140  enum v4l2_colorspace cs;
141 
142  cs = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
143  buf->context->format.fmt.pix_mp.colorspace :
144  buf->context->format.fmt.pix.colorspace;
145 
146  ycbcr = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
147  buf->context->format.fmt.pix_mp.ycbcr_enc:
148  buf->context->format.fmt.pix.ycbcr_enc;
149 
150  switch(cs) {
151  case V4L2_COLORSPACE_SRGB: return AVCOL_SPC_RGB;
152  case V4L2_COLORSPACE_REC709: return AVCOL_SPC_BT709;
153  case V4L2_COLORSPACE_470_SYSTEM_M: return AVCOL_SPC_FCC;
154  case V4L2_COLORSPACE_470_SYSTEM_BG: return AVCOL_SPC_BT470BG;
155  case V4L2_COLORSPACE_SMPTE170M: return AVCOL_SPC_SMPTE170M;
156  case V4L2_COLORSPACE_SMPTE240M: return AVCOL_SPC_SMPTE240M;
157  case V4L2_COLORSPACE_BT2020:
158  if (ycbcr == V4L2_YCBCR_ENC_BT2020_CONST_LUM)
159  return AVCOL_SPC_BT2020_CL;
160  else
161  return AVCOL_SPC_BT2020_NCL;
162  default:
163  break;
164  }
165 
166  return AVCOL_SPC_UNSPECIFIED;
167 }
168 
169 static enum AVColorTransferCharacteristic v4l2_get_color_trc(V4L2Buffer *buf)
170 {
171  enum v4l2_ycbcr_encoding ycbcr;
172  enum v4l2_xfer_func xfer;
173  enum v4l2_colorspace cs;
174 
175  cs = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
176  buf->context->format.fmt.pix_mp.colorspace :
177  buf->context->format.fmt.pix.colorspace;
178 
179  ycbcr = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
180  buf->context->format.fmt.pix_mp.ycbcr_enc:
181  buf->context->format.fmt.pix.ycbcr_enc;
182 
183  xfer = V4L2_TYPE_IS_MULTIPLANAR(buf->buf.type) ?
184  buf->context->format.fmt.pix_mp.xfer_func:
185  buf->context->format.fmt.pix.xfer_func;
186 
187  switch (xfer) {
188  case V4L2_XFER_FUNC_709: return AVCOL_TRC_BT709;
189  case V4L2_XFER_FUNC_SRGB: return AVCOL_TRC_IEC61966_2_1;
190  default:
191  break;
192  }
193 
194  switch (cs) {
195  case V4L2_COLORSPACE_470_SYSTEM_M: return AVCOL_TRC_GAMMA22;
196  case V4L2_COLORSPACE_470_SYSTEM_BG: return AVCOL_TRC_GAMMA28;
197  case V4L2_COLORSPACE_SMPTE170M: return AVCOL_TRC_SMPTE170M;
198  case V4L2_COLORSPACE_SMPTE240M: return AVCOL_TRC_SMPTE240M;
199  default:
200  break;
201  }
202 
203  switch (ycbcr) {
204  case V4L2_YCBCR_ENC_XV709:
205  case V4L2_YCBCR_ENC_XV601: return AVCOL_TRC_BT1361_ECG;
206  default:
207  break;
208  }
209 
210  return AVCOL_TRC_UNSPECIFIED;
211 }
212 
213 static void v4l2_free_buffer(void *opaque, uint8_t *unused)
214 {
215  V4L2Buffer* avbuf = opaque;
216  V4L2m2mContext *s = buf_to_m2mctx(avbuf);
217 
218  if (atomic_fetch_sub(&avbuf->context_refcount, 1) == 1) {
219  atomic_fetch_sub_explicit(&s->refcount, 1, memory_order_acq_rel);
220 
221  if (s->reinit) {
222  if (!atomic_load(&s->refcount))
223  sem_post(&s->refsync);
224  } else {
225  if (s->draining && V4L2_TYPE_IS_OUTPUT(avbuf->context->type)) {
226  /* no need to queue more buffers to the driver */
227  avbuf->status = V4L2BUF_AVAILABLE;
228  }
229  else if (avbuf->context->streamon)
230  ff_v4l2_buffer_enqueue(avbuf);
231  }
232 
233  av_buffer_unref(&avbuf->context_ref);
234  }
235 }
236 
237 static int v4l2_buf_increase_ref(V4L2Buffer *in)
238 {
239  V4L2m2mContext *s = buf_to_m2mctx(in);
240 
241  if (in->context_ref)
242  atomic_fetch_add(&in->context_refcount, 1);
243  else {
244  in->context_ref = av_buffer_ref(s->self_ref);
245  if (!in->context_ref)
246  return AVERROR(ENOMEM);
247 
248  in->context_refcount = 1;
249  }
250 
251  in->status = V4L2BUF_RET_USER;
252  atomic_fetch_add_explicit(&s->refcount, 1, memory_order_relaxed);
253 
254  return 0;
255 }
256 
257 static int v4l2_buf_to_bufref(V4L2Buffer *in, int plane, AVBufferRef **buf)
258 {
259  int ret;
260 
261  if (plane >= in->num_planes)
262  return AVERROR(EINVAL);
263 
264  /* even though most encoders return 0 in data_offset encoding vp8 does require this value */
265  *buf = av_buffer_create((char *)in->plane_info[plane].mm_addr + in->planes[plane].data_offset,
266  in->plane_info[plane].length, v4l2_free_buffer, in, 0);
267  if (!*buf)
268  return AVERROR(ENOMEM);
269 
270  ret = v4l2_buf_increase_ref(in);
271  if (ret)
272  av_buffer_unref(buf);
273 
274  return ret;
275 }
276 
277 static int v4l2_bufref_to_buf(V4L2Buffer *out, int plane, const uint8_t* data, int size, int offset)
278 {
279  unsigned int bytesused, length;
280 
281  if (plane >= out->num_planes)
282  return AVERROR(EINVAL);
283 
284  length = out->plane_info[plane].length;
285  bytesused = FFMIN(size+offset, length);
286 
287  memcpy((uint8_t*)out->plane_info[plane].mm_addr+offset, data, FFMIN(size, length-offset));
288 
289  if (V4L2_TYPE_IS_MULTIPLANAR(out->buf.type)) {
290  out->planes[plane].bytesused = bytesused;
291  out->planes[plane].length = length;
292  } else {
293  out->buf.bytesused = bytesused;
294  out->buf.length = length;
295  }
296 
297  return 0;
298 }
299 
300 static int v4l2_buffer_buf_to_swframe(AVFrame *frame, V4L2Buffer *avbuf)
301 {
302  int i, ret;
303 
304  frame->format = avbuf->context->av_pix_fmt;
305 
306  for (i = 0; i < avbuf->num_planes; i++) {
307  ret = v4l2_buf_to_bufref(avbuf, i, &frame->buf[i]);
308  if (ret)
309  return ret;
310 
311  frame->linesize[i] = avbuf->plane_info[i].bytesperline;
312  frame->data[i] = frame->buf[i]->data;
313  }
314 
315  /* fixup special cases */
316  switch (avbuf->context->av_pix_fmt) {
317  case AV_PIX_FMT_NV12:
318  case AV_PIX_FMT_NV21:
319  if (avbuf->num_planes > 1)
320  break;
321  frame->linesize[1] = avbuf->plane_info[0].bytesperline;
322  frame->data[1] = frame->buf[0]->data + avbuf->plane_info[0].bytesperline * avbuf->context->format.fmt.pix_mp.height;
323  break;
324 
325  case AV_PIX_FMT_YUV420P:
326  if (avbuf->num_planes > 1)
327  break;
328  frame->linesize[1] = avbuf->plane_info[0].bytesperline >> 1;
329  frame->linesize[2] = avbuf->plane_info[0].bytesperline >> 1;
330  frame->data[1] = frame->buf[0]->data + avbuf->plane_info[0].bytesperline * avbuf->context->format.fmt.pix_mp.height;
331  frame->data[2] = frame->data[1] + ((avbuf->plane_info[0].bytesperline * avbuf->context->format.fmt.pix_mp.height) >> 2);
332  break;
333 
334  default:
335  break;
336  }
337 
338  return 0;
339 }
340 
341 static int v4l2_buffer_swframe_to_buf(const AVFrame *frame, V4L2Buffer *out)
342 {
343  int i, ret;
344  struct v4l2_format fmt = out->context->format;
345  int pixel_format = V4L2_TYPE_IS_MULTIPLANAR(fmt.type) ?
346  fmt.fmt.pix_mp.pixelformat : fmt.fmt.pix.pixelformat;
347  int height = V4L2_TYPE_IS_MULTIPLANAR(fmt.type) ?
348  fmt.fmt.pix_mp.height : fmt.fmt.pix.height;
349  int is_planar_format = 0;
350 
351  switch (pixel_format) {
352  case V4L2_PIX_FMT_YUV420M:
353  case V4L2_PIX_FMT_YVU420M:
354 #ifdef V4L2_PIX_FMT_YUV422M
355  case V4L2_PIX_FMT_YUV422M:
356 #endif
357 #ifdef V4L2_PIX_FMT_YVU422M
358  case V4L2_PIX_FMT_YVU422M:
359 #endif
360 #ifdef V4L2_PIX_FMT_YUV444M
361  case V4L2_PIX_FMT_YUV444M:
362 #endif
363 #ifdef V4L2_PIX_FMT_YVU444M
364  case V4L2_PIX_FMT_YVU444M:
365 #endif
366  case V4L2_PIX_FMT_NV12M:
367  case V4L2_PIX_FMT_NV21M:
368  case V4L2_PIX_FMT_NV12MT_16X16:
369  case V4L2_PIX_FMT_NV12MT:
370  case V4L2_PIX_FMT_NV16M:
371  case V4L2_PIX_FMT_NV61M:
372  is_planar_format = 1;
373  }
374 
375  if (!is_planar_format) {
376  const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(frame->format);
377  int planes_nb = 0;
378  int offset = 0;
379 
380  for (i = 0; i < desc->nb_components; i++)
381  planes_nb = FFMAX(planes_nb, desc->comp[i].plane + 1);
382 
383  for (i = 0; i < planes_nb; i++) {
384  int size, h = height;
385  if (i == 1 || i == 2) {
386  h = AV_CEIL_RSHIFT(h, desc->log2_chroma_h);
387  }
388  size = frame->linesize[i] * h;
389  ret = v4l2_bufref_to_buf(out, 0, frame->data[i], size, offset);
390  if (ret)
391  return ret;
392  offset += size;
393  }
394  return 0;
395  }
396 
397  for (i = 0; i < out->num_planes; i++) {
398  ret = v4l2_bufref_to_buf(out, i, frame->buf[i]->data, frame->buf[i]->size, 0);
399  if (ret)
400  return ret;
401  }
402 
403  return 0;
404 }
405 
406 /******************************************************************************
407  *
408  * V4L2Buffer interface
409  *
410  ******************************************************************************/
411 
412 int ff_v4l2_buffer_avframe_to_buf(const AVFrame *frame, V4L2Buffer *out)
413 {
414  v4l2_set_pts(out, frame->pts);
415 
416  return v4l2_buffer_swframe_to_buf(frame, out);
417 }
418 
419 int ff_v4l2_buffer_buf_to_avframe(AVFrame *frame, V4L2Buffer *avbuf)
420 {
421  int ret;
422 
423  av_frame_unref(frame);
424 
425  /* 1. get references to the actual data */
426  ret = v4l2_buffer_buf_to_swframe(frame, avbuf);
427  if (ret)
428  return ret;
429 
430  /* 2. get frame information */
431  frame->key_frame = !!(avbuf->buf.flags & V4L2_BUF_FLAG_KEYFRAME);
432  frame->color_primaries = v4l2_get_color_primaries(avbuf);
433  frame->colorspace = v4l2_get_color_space(avbuf);
434  frame->color_range = v4l2_get_color_range(avbuf);
435  frame->color_trc = v4l2_get_color_trc(avbuf);
436  frame->pts = v4l2_get_pts(avbuf);
437  frame->pkt_dts = AV_NOPTS_VALUE;
438 
439  /* these values are updated also during re-init in v4l2_process_driver_event */
440  frame->height = avbuf->context->height;
441  frame->width = avbuf->context->width;
442  frame->sample_aspect_ratio = avbuf->context->sample_aspect_ratio;
443 
444  /* 3. report errors upstream */
445  if (avbuf->buf.flags & V4L2_BUF_FLAG_ERROR) {
446  av_log(logger(avbuf), AV_LOG_ERROR, "%s: driver decode error\n", avbuf->context->name);
447  frame->decode_error_flags |= FF_DECODE_ERROR_INVALID_BITSTREAM;
448  }
449 
450  return 0;
451 }
452 
453 int ff_v4l2_buffer_buf_to_avpkt(AVPacket *pkt, V4L2Buffer *avbuf)
454 {
455  int ret;
456 
457  av_packet_unref(pkt);
458  ret = v4l2_buf_to_bufref(avbuf, 0, &pkt->buf);
459  if (ret)
460  return ret;
461 
462  pkt->size = V4L2_TYPE_IS_MULTIPLANAR(avbuf->buf.type) ? avbuf->buf.m.planes[0].bytesused : avbuf->buf.bytesused;
463  pkt->data = pkt->buf->data;
464 
465  if (avbuf->buf.flags & V4L2_BUF_FLAG_KEYFRAME)
466  pkt->flags |= AV_PKT_FLAG_KEY;
467 
468  if (avbuf->buf.flags & V4L2_BUF_FLAG_ERROR) {
469  av_log(logger(avbuf), AV_LOG_ERROR, "%s driver encode error\n", avbuf->context->name);
470  pkt->flags |= AV_PKT_FLAG_CORRUPT;
471  }
472 
473  pkt->dts = pkt->pts = v4l2_get_pts(avbuf);
474 
475  return 0;
476 }
477 
478 int ff_v4l2_buffer_avpkt_to_buf(const AVPacket *pkt, V4L2Buffer *out)
479 {
480  int ret;
481 
482  ret = v4l2_bufref_to_buf(out, 0, pkt->data, pkt->size, 0);
483  if (ret)
484  return ret;
485 
486  v4l2_set_pts(out, pkt->pts);
487 
488  if (pkt->flags & AV_PKT_FLAG_KEY)
489  out->flags = V4L2_BUF_FLAG_KEYFRAME;
490 
491  return 0;
492 }
493 
494 int ff_v4l2_buffer_initialize(V4L2Buffer* avbuf, int index)
495 {
496  V4L2Context *ctx = avbuf->context;
497  int ret, i;
498 
499  avbuf->buf.memory = V4L2_MEMORY_MMAP;
500  avbuf->buf.type = ctx->type;
501  avbuf->buf.index = index;
502 
503  if (V4L2_TYPE_IS_MULTIPLANAR(ctx->type)) {
504  avbuf->buf.length = VIDEO_MAX_PLANES;
505  avbuf->buf.m.planes = avbuf->planes;
506  }
507 
508  ret = ioctl(buf_to_m2mctx(avbuf)->fd, VIDIOC_QUERYBUF, &avbuf->buf);
509  if (ret < 0)
510  return AVERROR(errno);
511 
512  if (V4L2_TYPE_IS_MULTIPLANAR(ctx->type)) {
513  avbuf->num_planes = 0;
514  /* in MP, the V4L2 API states that buf.length means num_planes */
515  for (i = 0; i < avbuf->buf.length; i++) {
516  if (avbuf->buf.m.planes[i].length)
517  avbuf->num_planes++;
518  }
519  } else
520  avbuf->num_planes = 1;
521 
522  for (i = 0; i < avbuf->num_planes; i++) {
523 
524  avbuf->plane_info[i].bytesperline = V4L2_TYPE_IS_MULTIPLANAR(ctx->type) ?
525  ctx->format.fmt.pix_mp.plane_fmt[i].bytesperline :
526  ctx->format.fmt.pix.bytesperline;
527 
528  if (V4L2_TYPE_IS_MULTIPLANAR(ctx->type)) {
529  avbuf->plane_info[i].length = avbuf->buf.m.planes[i].length;
530  avbuf->plane_info[i].mm_addr = mmap(NULL, avbuf->buf.m.planes[i].length,
531  PROT_READ | PROT_WRITE, MAP_SHARED,
532  buf_to_m2mctx(avbuf)->fd, avbuf->buf.m.planes[i].m.mem_offset);
533  } else {
534  avbuf->plane_info[i].length = avbuf->buf.length;
535  avbuf->plane_info[i].mm_addr = mmap(NULL, avbuf->buf.length,
536  PROT_READ | PROT_WRITE, MAP_SHARED,
537  buf_to_m2mctx(avbuf)->fd, avbuf->buf.m.offset);
538  }
539 
540  if (avbuf->plane_info[i].mm_addr == MAP_FAILED)
541  return AVERROR(ENOMEM);
542  }
543 
544  avbuf->status = V4L2BUF_AVAILABLE;
545 
546  if (V4L2_TYPE_IS_OUTPUT(ctx->type))
547  return 0;
548 
549  if (V4L2_TYPE_IS_MULTIPLANAR(ctx->type)) {
550  avbuf->buf.m.planes = avbuf->planes;
551  avbuf->buf.length = avbuf->num_planes;
552 
553  } else {
554  avbuf->buf.bytesused = avbuf->planes[0].bytesused;
555  avbuf->buf.length = avbuf->planes[0].length;
556  }
557 
558  return ff_v4l2_buffer_enqueue(avbuf);
559 }
560 
561 int ff_v4l2_buffer_enqueue(V4L2Buffer* avbuf)
562 {
563  int ret;
564 
565  avbuf->buf.flags = avbuf->flags;
566 
567  ret = ioctl(buf_to_m2mctx(avbuf)->fd, VIDIOC_QBUF, &avbuf->buf);
568  if (ret < 0)
569  return AVERROR(errno);
570 
571  avbuf->status = V4L2BUF_IN_DRIVER;
572 
573  return 0;
574 }
V4L2Buffer::num_planes
int num_planes
Definition: v4l2_buffers.h:60
av_packet_unref
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:424
V4L2Context::av_pix_fmt
enum AVPixelFormat av_pix_fmt
AVPixelFormat corresponding to this buffer context.
Definition: v4l2_context.h:54
v4l2_get_color_space
static enum AVColorSpace v4l2_get_color_space(V4L2Buffer *buf)
Definition: v4l2_buffers.c:137
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
AVColorTransferCharacteristic
AVColorTransferCharacteristic
Color Transfer Characteristic.
Definition: pixfmt.h:494
out
FILE * out
Definition: movenc.c:54
v4l2_buffers.h
av_pix_fmt_desc_get
const AVPixFmtDescriptor * av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
Definition: pixdesc.c:2660
AVBufferRef::data
uint8_t * data
The data buffer.
Definition: buffer.h:90
output
filter_frame For filters that do not use the this method is called when a frame is pushed to the filter s input It can be called at any time except in a reentrant way If the input frame is enough to produce output
Definition: filter_design.txt:225
ff_v4l2_buffer_buf_to_avpkt
int ff_v4l2_buffer_buf_to_avpkt(AVPacket *pkt, V4L2Buffer *avbuf)
Extracts the data from a V4L2Buffer to an AVPacket.
Definition: v4l2_buffers.c:453
V4L2m2mContext
Definition: v4l2_m2m.h:43
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:317
V4L2Buffer::V4L2Plane_info::length
size_t length
Definition: v4l2_buffers.h:57
pixdesc.h
index
fg index
Definition: ffmpeg_filter.c:167
v4l2_set_pts
static void v4l2_set_pts(V4L2Buffer *out, int64_t pts)
Definition: v4l2_buffers.c:61
AVCOL_RANGE_JPEG
@ AVCOL_RANGE_JPEG
Full range content.
Definition: pixfmt.h:597
internal.h
AVPacket::data
uint8_t * data
Definition: packet.h:373
AVCOL_TRC_UNSPECIFIED
@ AVCOL_TRC_UNSPECIFIED
Definition: pixfmt.h:497
data
const char data[16]
Definition: mxf.c:143
AVCOL_SPC_RGB
@ AVCOL_SPC_RGB
order of coefficients is actually GBR, also IEC 61966-2-1 (sRGB), YZX and ST 428-1
Definition: pixfmt.h:524
USEC_PER_SEC
#define USEC_PER_SEC
Definition: v4l2_buffers.c:37
FFMAX
#define FFMAX(a, b)
Definition: macros.h:47
av_buffer_ref
AVBufferRef * av_buffer_ref(const AVBufferRef *buf)
Create a new reference to an AVBuffer.
Definition: buffer.c:103
AVColorPrimaries
AVColorPrimaries
Chromaticity coordinates of the source primaries.
Definition: pixfmt.h:469
logger
static AVCodecContext * logger(V4L2Buffer *buf)
Definition: v4l2_buffers.c:47
AVCOL_SPC_BT2020_CL
@ AVCOL_SPC_BT2020_CL
ITU-R BT2020 constant luminance system.
Definition: pixfmt.h:535
AV_PKT_FLAG_KEY
#define AV_PKT_FLAG_KEY
The packet contains a keyframe.
Definition: packet.h:428
v4l2_get_timebase
static AVRational v4l2_get_timebase(V4L2Buffer *avbuf)
Definition: v4l2_buffers.c:52
v4l2_bufref_to_buf
static int v4l2_bufref_to_buf(V4L2Buffer *out, int plane, const uint8_t *data, int size, int offset)
Definition: v4l2_buffers.c:277
AVCOL_SPC_BT470BG
@ AVCOL_SPC_BT470BG
also ITU-R BT601-6 625 / ITU-R BT1358 625 / ITU-R BT1700 625 PAL & SECAM / IEC 61966-2-4 xvYCC601
Definition: pixfmt.h:529
AVCOL_TRC_IEC61966_2_1
@ AVCOL_TRC_IEC61966_2_1
IEC 61966-2-1 (sRGB or sYCC)
Definition: pixfmt.h:508
v4l2_buf_increase_ref
static int v4l2_buf_increase_ref(V4L2Buffer *in)
Definition: v4l2_buffers.c:237
V4L2Buffer::buf
struct v4l2_buffer buf
Definition: v4l2_buffers.h:63
ff_v4l2_buffer_buf_to_avframe
int ff_v4l2_buffer_buf_to_avframe(AVFrame *frame, V4L2Buffer *avbuf)
Extracts the data from a V4L2Buffer to an AVFrame.
Definition: v4l2_buffers.c:419
AVCOL_TRC_GAMMA28
@ AVCOL_TRC_GAMMA28
also ITU-R BT470BG
Definition: pixfmt.h:500
pts
static int64_t pts
Definition: transcode_aac.c:653
atomic_fetch_sub
#define atomic_fetch_sub(object, operand)
Definition: stdatomic.h:137
V4L2Context::streamon
int streamon
Whether the stream has been started (VIDIOC_STREAMON has been sent).
Definition: v4l2_context.h:88
AVCOL_TRC_GAMMA22
@ AVCOL_TRC_GAMMA22
also ITU-R BT470M / ITU-R BT1700 625 PAL & SECAM
Definition: pixfmt.h:499
V4L2Buffer::context
struct V4L2Context * context
Definition: v4l2_buffers.h:46
pkt
AVPacket * pkt
Definition: movenc.c:59
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
ff_v4l2_buffer_avframe_to_buf
int ff_v4l2_buffer_avframe_to_buf(const AVFrame *frame, V4L2Buffer *out)
Extracts the data from an AVFrame to a V4L2Buffer.
Definition: v4l2_buffers.c:412
AV_PKT_FLAG_CORRUPT
#define AV_PKT_FLAG_CORRUPT
The packet content is corrupted.
Definition: packet.h:429
V4L2Buffer
V4L2Buffer (wrapper for v4l2_buffer management)
Definition: v4l2_buffers.h:44
s
#define s(width, name)
Definition: cbs_vp9.c:257
AVCOL_TRC_BT1361_ECG
@ AVCOL_TRC_BT1361_ECG
ITU-R BT1361 Extended Colour Gamut.
Definition: pixfmt.h:507
AV_CEIL_RSHIFT
#define AV_CEIL_RSHIFT(a, b)
Definition: common.h:51
AVCOL_SPC_SMPTE170M
@ AVCOL_SPC_SMPTE170M
also ITU-R BT601-6 525 / ITU-R BT1358 525 / ITU-R BT1700 NTSC / functionally identical to above
Definition: pixfmt.h:530
V4L2BUF_RET_USER
@ V4L2BUF_RET_USER
Definition: v4l2_buffers.h:38
ctx
AVFormatContext * ctx
Definition: movenc.c:48
av_rescale_q
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
Rescale a 64-bit integer by 2 rational numbers.
Definition: mathematics.c:141
v4l2_get_color_primaries
static enum AVColorPrimaries v4l2_get_color_primaries(V4L2Buffer *buf)
Definition: v4l2_buffers.c:85
AV_PIX_FMT_YUV420P
@ AV_PIX_FMT_YUV420P
planar YUV 4:2:0, 12bpp, (1 Cr & Cb sample per 2x2 Y samples)
Definition: pixfmt.h:66
AVCOL_PRI_SMPTE240M
@ AVCOL_PRI_SMPTE240M
identical to above, also called "SMPTE C" even though it uses D65
Definition: pixfmt.h:478
atomic_load
#define atomic_load(object)
Definition: stdatomic.h:93
AVCOL_PRI_UNSPECIFIED
@ AVCOL_PRI_UNSPECIFIED
Definition: pixfmt.h:472
AVCOL_PRI_BT470BG
@ AVCOL_PRI_BT470BG
also ITU-R BT601-6 625 / ITU-R BT1358 625 / ITU-R BT1700 625 PAL & SECAM
Definition: pixfmt.h:476
AVCOL_PRI_SMPTE170M
@ AVCOL_PRI_SMPTE170M
also ITU-R BT601-6 525 / ITU-R BT1358 525 / ITU-R BT1700 NTSC
Definition: pixfmt.h:477
ff_v4l2_buffer_enqueue
int ff_v4l2_buffer_enqueue(V4L2Buffer *avbuf)
Enqueues a V4L2Buffer.
Definition: v4l2_buffers.c:561
AVPacket::buf
AVBufferRef * buf
A reference to the reference-counted buffer where the packet data is stored.
Definition: packet.h:356
v4l2_buffer_swframe_to_buf
static int v4l2_buffer_swframe_to_buf(const AVFrame *frame, V4L2Buffer *out)
Definition: v4l2_buffers.c:341
V4L2Context
Definition: v4l2_context.h:37
NULL
#define NULL
Definition: coverity.c:32
FF_DECODE_ERROR_INVALID_BITSTREAM
#define FF_DECODE_ERROR_INVALID_BITSTREAM
Definition: frame.h:618
av_buffer_unref
void av_buffer_unref(AVBufferRef **buf)
Free a given reference and automatically free the buffer if there are no more references to it.
Definition: buffer.c:139
container_of
#define container_of(ptr, type, member)
Definition: v4l2_m2m.h:35
AVRational
Rational number (pair of numerator and denominator).
Definition: rational.h:58
V4L2Context::type
enum v4l2_buf_type type
Type of this buffer context.
Definition: v4l2_context.h:48
AVCOL_PRI_BT709
@ AVCOL_PRI_BT709
also ITU-R BT1361 / IEC 61966-2-4 / SMPTE RP 177 Annex B
Definition: pixfmt.h:471
V4L2Buffer::V4L2Plane_info::mm_addr
void * mm_addr
Definition: v4l2_buffers.h:56
v4l2_get_color_range
static enum AVColorRange v4l2_get_color_range(V4L2Buffer *buf)
Definition: v4l2_buffers.c:119
atomic_fetch_sub_explicit
#define atomic_fetch_sub_explicit(object, operand, order)
Definition: stdatomic.h:152
AVCOL_RANGE_UNSPECIFIED
@ AVCOL_RANGE_UNSPECIFIED
Definition: pixfmt.h:563
ff_v4l2_buffer_avpkt_to_buf
int ff_v4l2_buffer_avpkt_to_buf(const AVPacket *pkt, V4L2Buffer *out)
Extracts the data from an AVPacket to a V4L2Buffer.
Definition: v4l2_buffers.c:478
av_buffer_create
AVBufferRef * av_buffer_create(uint8_t *data, size_t size, void(*free)(void *opaque, uint8_t *data), void *opaque, int flags)
Create an AVBuffer from an existing array.
Definition: buffer.c:55
AVCOL_PRI_BT2020
@ AVCOL_PRI_BT2020
ITU-R BT2020.
Definition: pixfmt.h:480
V4L2BUF_AVAILABLE
@ V4L2BUF_AVAILABLE
Definition: v4l2_buffers.h:36
V4L2Context::width
int width
Width and height of the frames it produces (in case of a capture context, e.g.
Definition: v4l2_context.h:72
AVPacket::size
int size
Definition: packet.h:374
V4L2Buffer::context_ref
AVBufferRef * context_ref
Definition: v4l2_buffers.h:50
AVCOL_TRC_SMPTE240M
@ AVCOL_TRC_SMPTE240M
Definition: pixfmt.h:502
V4L2Buffer::plane_info
struct V4L2Buffer::V4L2Plane_info plane_info[VIDEO_MAX_PLANES]
V4L2BUF_IN_DRIVER
@ V4L2BUF_IN_DRIVER
Definition: v4l2_buffers.h:37
size
int size
Definition: twinvq_data.h:10344
atomic_fetch_add_explicit
#define atomic_fetch_add_explicit(object, operand, order)
Definition: stdatomic.h:149
AV_NOPTS_VALUE
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
v4l2_get_pts
static int64_t v4l2_get_pts(V4L2Buffer *avbuf)
Definition: v4l2_buffers.c:74
AVPacket::dts
int64_t dts
Decompression timestamp in AVStream->time_base units; the time at which the packet is decompressed.
Definition: packet.h:372
v4l2_timebase
static AVRational v4l2_timebase
Definition: v4l2_buffers.c:38
height
#define height
offset
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf offset
Definition: writing_filters.txt:86
AVPacket::flags
int flags
A combination of AV_PKT_FLAG values.
Definition: packet.h:379
V4L2Buffer::context_refcount
atomic_uint context_refcount
Definition: v4l2_buffers.h:51
AVCOL_TRC_BT709
@ AVCOL_TRC_BT709
also ITU-R BT1361
Definition: pixfmt.h:496
V4L2m2mContext::avctx
AVCodecContext * avctx
Definition: v4l2_m2m.h:52
AVCOL_SPC_SMPTE240M
@ AVCOL_SPC_SMPTE240M
derived from 170M primaries and D65 white point, 170M is derived from BT470 System M's primaries
Definition: pixfmt.h:531
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:271
AVPacket::pts
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:366
AVCOL_SPC_BT2020_NCL
@ AVCOL_SPC_BT2020_NCL
ITU-R BT2020 non-constant luminance system.
Definition: pixfmt.h:534
v4l2_buffer_buf_to_swframe
static int v4l2_buffer_buf_to_swframe(AVFrame *frame, V4L2Buffer *avbuf)
Definition: v4l2_buffers.c:300
AVColorSpace
AVColorSpace
YUV colorspace type.
Definition: pixfmt.h:523
V4L2Buffer::flags
int flags
Definition: v4l2_buffers.h:66
V4L2Buffer::planes
struct v4l2_plane planes[VIDEO_MAX_PLANES]
Definition: v4l2_buffers.h:64
FFMIN
#define FFMIN(a, b)
Definition: macros.h:49
V4L2Buffer::V4L2Plane_info::bytesperline
int bytesperline
Definition: v4l2_buffers.h:55
av_frame_unref
void av_frame_unref(AVFrame *frame)
Unreference all the buffers referenced by frame and reset the frame fields.
Definition: frame.c:435
AV_PIX_FMT_NV21
@ AV_PIX_FMT_NV21
as above, but U and V bytes are swapped
Definition: pixfmt.h:90
v4l2_context.h
AVCOL_SPC_UNSPECIFIED
@ AVCOL_SPC_UNSPECIFIED
Definition: pixfmt.h:526
v4l2_buf_to_bufref
static int v4l2_buf_to_bufref(V4L2Buffer *in, int plane, AVBufferRef **buf)
Definition: v4l2_buffers.c:257
AVCOL_RANGE_MPEG
@ AVCOL_RANGE_MPEG
Narrow or limited range content.
Definition: pixfmt.h:580
avcodec.h
AVCOL_PRI_BT470M
@ AVCOL_PRI_BT470M
also FCC Title 47 Code of Federal Regulations 73.682 (a)(20)
Definition: pixfmt.h:474
ret
ret
Definition: filter_design.txt:187
AV_PIX_FMT_NV12
@ AV_PIX_FMT_NV12
planar YUV 4:2:0, 12bpp, 1 plane for Y and 1 plane for the UV components, which are interleaved (firs...
Definition: pixfmt.h:89
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
buf_to_m2mctx
static V4L2m2mContext * buf_to_m2mctx(V4L2Buffer *buf)
Definition: v4l2_buffers.c:40
V4L2Context::height
int height
Definition: v4l2_context.h:72
AVCodecContext
main external API structure.
Definition: avcodec.h:383
atomic_fetch_add
#define atomic_fetch_add(object, operand)
Definition: stdatomic.h:131
AVCOL_SPC_FCC
@ AVCOL_SPC_FCC
FCC Title 47 Code of Federal Regulations 73.682 (a)(20)
Definition: pixfmt.h:528
sem_post
#define sem_post(psem)
Definition: semaphore.h:26
AVCOL_TRC_SMPTE170M
@ AVCOL_TRC_SMPTE170M
also ITU-R BT601-6 525 or 625 / ITU-R BT1358 525 or 625 / ITU-R BT1700 NTSC
Definition: pixfmt.h:501
v4l2_free_buffer
static void v4l2_free_buffer(void *opaque, uint8_t *unused)
Definition: v4l2_buffers.c:213
V4L2Context::name
const char * name
context name.
Definition: v4l2_context.h:41
desc
const char * desc
Definition: libsvtav1.c:79
AVBufferRef
A reference to a data buffer.
Definition: buffer.h:82
AVPixFmtDescriptor
Descriptor that unambiguously describes how the bits of a pixel are stored in the up to 4 data planes...
Definition: pixdesc.h:69
AVPacket
This structure stores compressed data.
Definition: packet.h:350
V4L2Context::format
struct v4l2_format format
Format returned by the driver after initializing the buffer context.
Definition: v4l2_context.h:66
v4l2_m2m.h
ff_v4l2_buffer_initialize
int ff_v4l2_buffer_initialize(V4L2Buffer *avbuf, int index)
Initializes a V4L2Buffer.
Definition: v4l2_buffers.c:494
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
v4l2_get_color_trc
static enum AVColorTransferCharacteristic v4l2_get_color_trc(V4L2Buffer *buf)
Definition: v4l2_buffers.c:169
h
h
Definition: vp9dsp_template.c:2038
AVCOL_SPC_BT709
@ AVCOL_SPC_BT709
also ITU-R BT1361 / IEC 61966-2-4 xvYCC709 / derived in SMPTE RP 177 Annex B
Definition: pixfmt.h:525
AVColorRange
AVColorRange
Visual content value range.
Definition: pixfmt.h:562
V4L2Context::sample_aspect_ratio
AVRational sample_aspect_ratio
Definition: v4l2_context.h:73
V4L2Buffer::status
enum V4L2Buffer_status status
Definition: v4l2_buffers.h:67
Generated on Wed Aug 24 2022 21:37:57 for FFmpeg by   doxygen 1.8.17