FFmpeg
v4l2_m2m.c
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1 /*
2  * V4L mem2mem
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 <dirent.h>
29 #include <fcntl.h>
30 #include "libavcodec/avcodec.h"
31 #include "libavcodec/internal.h"
32 #include "libavutil/pixdesc.h"
33 #include "libavutil/imgutils.h"
34 #include "libavutil/pixfmt.h"
35 #include "v4l2_context.h"
36 #include "v4l2_fmt.h"
37 #include "v4l2_m2m.h"
38 
39 static inline int v4l2_splane_video(struct v4l2_capability *cap)
40 {
41  if (cap->capabilities & (V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_VIDEO_OUTPUT) &&
42  cap->capabilities & V4L2_CAP_STREAMING)
43  return 1;
44 
45  if (cap->capabilities & V4L2_CAP_VIDEO_M2M)
46  return 1;
47 
48  return 0;
49 }
50 
51 static inline int v4l2_mplane_video(struct v4l2_capability *cap)
52 {
53  if (cap->capabilities & (V4L2_CAP_VIDEO_CAPTURE_MPLANE | V4L2_CAP_VIDEO_OUTPUT_MPLANE) &&
54  cap->capabilities & V4L2_CAP_STREAMING)
55  return 1;
56 
57  if (cap->capabilities & V4L2_CAP_VIDEO_M2M_MPLANE)
58  return 1;
59 
60  return 0;
61 }
62 
64 {
65  struct v4l2_capability cap;
66  void *log_ctx = s->avctx;
67  int ret;
68 
69  s->capture.done = s->output.done = 0;
70  s->capture.name = "capture";
71  s->output.name = "output";
72  atomic_init(&s->refcount, 0);
73  sem_init(&s->refsync, 0, 0);
74 
75  memset(&cap, 0, sizeof(cap));
76  ret = ioctl(s->fd, VIDIOC_QUERYCAP, &cap);
77  if (ret < 0)
78  return ret;
79 
80  av_log(log_ctx, probe ? AV_LOG_DEBUG : AV_LOG_INFO,
81  "driver '%s' on card '%s' in %s mode\n", cap.driver, cap.card,
82  v4l2_mplane_video(&cap) ? "mplane" :
83  v4l2_splane_video(&cap) ? "splane" : "unknown");
84 
85  if (v4l2_mplane_video(&cap)) {
86  s->capture.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
87  s->output.type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
88  return 0;
89  }
90 
91  if (v4l2_splane_video(&cap)) {
92  s->capture.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
93  s->output.type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
94  return 0;
95  }
96 
97  return AVERROR(EINVAL);
98 }
99 
101 {
102  void *log_ctx = s->avctx;
103  int ret;
104 
105  s->fd = open(s->devname, O_RDWR | O_NONBLOCK, 0);
106  if (s->fd < 0)
107  return AVERROR(errno);
108 
109  ret = v4l2_prepare_contexts(s, 1);
110  if (ret < 0)
111  goto done;
112 
113  ret = ff_v4l2_context_get_format(&s->output, 1);
114  if (ret) {
115  av_log(log_ctx, AV_LOG_DEBUG, "v4l2 output format not supported\n");
116  goto done;
117  }
118 
119  ret = ff_v4l2_context_get_format(&s->capture, 1);
120  if (ret) {
121  av_log(log_ctx, AV_LOG_DEBUG, "v4l2 capture format not supported\n");
122  goto done;
123  }
124 
125 done:
126  if (close(s->fd) < 0) {
127  ret = AVERROR(errno);
128  av_log(log_ctx, AV_LOG_ERROR, "failure closing %s (%s)\n", s->devname, av_err2str(AVERROR(errno)));
129  }
130 
131  s->fd = -1;
132 
133  return ret;
134 }
135 
137 {
138  void *log_ctx = s->avctx;
139  int ret;
140  struct v4l2_format ofmt, cfmt;
141 
142  s->fd = open(s->devname, O_RDWR | O_NONBLOCK, 0);
143  if (s->fd < 0)
144  return AVERROR(errno);
145 
146  ret = v4l2_prepare_contexts(s, 0);
147  if (ret < 0)
148  goto error;
149 
150  ofmt = s->output.format;
151  cfmt = s->capture.format;
152  av_log(log_ctx, AV_LOG_INFO, "requesting formats: output=%s capture=%s\n",
153  av_fourcc2str(V4L2_TYPE_IS_MULTIPLANAR(ofmt.type) ?
154  ofmt.fmt.pix_mp.pixelformat :
155  ofmt.fmt.pix.pixelformat),
156  av_fourcc2str(V4L2_TYPE_IS_MULTIPLANAR(cfmt.type) ?
157  cfmt.fmt.pix_mp.pixelformat :
158  cfmt.fmt.pix.pixelformat));
159 
161  if (ret) {
162  av_log(log_ctx, AV_LOG_ERROR, "can't set v4l2 output format\n");
163  goto error;
164  }
165 
167  if (ret) {
168  av_log(log_ctx, AV_LOG_ERROR, "can't to set v4l2 capture format\n");
169  goto error;
170  }
171 
172  ret = ff_v4l2_context_init(&s->output);
173  if (ret) {
174  av_log(log_ctx, AV_LOG_ERROR, "no v4l2 output context's buffers\n");
175  goto error;
176  }
177 
178  /* decoder's buffers need to be updated at a later stage */
179  if (s->avctx && !av_codec_is_decoder(s->avctx->codec)) {
180  ret = ff_v4l2_context_init(&s->capture);
181  if (ret) {
182  av_log(log_ctx, AV_LOG_ERROR, "no v4l2 capture context's buffers\n");
183  goto error;
184  }
185  }
186 
187  return 0;
188 
189 error:
190  if (close(s->fd) < 0) {
191  ret = AVERROR(errno);
192  av_log(log_ctx, AV_LOG_ERROR, "error closing %s (%s)\n",
193  s->devname, av_err2str(AVERROR(errno)));
194  }
195  s->fd = -1;
196 
197  return ret;
198 }
199 
200 /******************************************************************************
201  *
202  * V4L2 M2M Interface
203  *
204  ******************************************************************************/
206 {
207  void *log_ctx = s->avctx;
208  int ret;
209 
210  av_log(log_ctx, AV_LOG_DEBUG, "reinit context\n");
211 
212  /* 1. streamoff */
213  ret = ff_v4l2_context_set_status(&s->capture, VIDIOC_STREAMOFF);
214  if (ret)
215  av_log(log_ctx, AV_LOG_ERROR, "capture VIDIOC_STREAMOFF\n");
216 
217  /* 2. unmap the capture buffers (v4l2 and ffmpeg):
218  * we must wait for all references to be released before being allowed
219  * to queue new buffers.
220  */
221  av_log(log_ctx, AV_LOG_DEBUG, "waiting for user to release AVBufferRefs\n");
222  if (atomic_load(&s->refcount))
223  while(sem_wait(&s->refsync) == -1 && errno == EINTR);
224 
226 
227  /* 3. get the new capture format */
228  ret = ff_v4l2_context_get_format(&s->capture, 0);
229  if (ret) {
230  av_log(log_ctx, AV_LOG_ERROR, "query the new capture format\n");
231  return ret;
232  }
233 
234  /* 4. set the capture format */
236  if (ret) {
237  av_log(log_ctx, AV_LOG_ERROR, "setting capture format\n");
238  return ret;
239  }
240 
241  /* 5. complete reinit */
242  s->draining = 0;
243  s->reinit = 0;
244 
245  return 0;
246 }
247 
249 {
250  void *log_ctx = s->avctx;
251  int ret;
252 
253  av_log(log_ctx, AV_LOG_DEBUG, "%s full reinit\n", s->devname);
254 
255  /* wait for pending buffer references */
256  if (atomic_load(&s->refcount))
257  while(sem_wait(&s->refsync) == -1 && errno == EINTR);
258 
259  ret = ff_v4l2_context_set_status(&s->output, VIDIOC_STREAMOFF);
260  if (ret) {
261  av_log(log_ctx, AV_LOG_ERROR, "output VIDIOC_STREAMOFF\n");
262  goto error;
263  }
264 
265  ret = ff_v4l2_context_set_status(&s->capture, VIDIOC_STREAMOFF);
266  if (ret) {
267  av_log(log_ctx, AV_LOG_ERROR, "capture VIDIOC_STREAMOFF\n");
268  goto error;
269  }
270 
271  /* release and unmmap the buffers */
274 
275  /* start again now that we know the stream dimensions */
276  s->draining = 0;
277  s->reinit = 0;
278 
279  ret = ff_v4l2_context_get_format(&s->output, 0);
280  if (ret) {
281  av_log(log_ctx, AV_LOG_DEBUG, "v4l2 output format not supported\n");
282  goto error;
283  }
284 
285  ret = ff_v4l2_context_get_format(&s->capture, 0);
286  if (ret) {
287  av_log(log_ctx, AV_LOG_DEBUG, "v4l2 capture format not supported\n");
288  goto error;
289  }
290 
292  if (ret) {
293  av_log(log_ctx, AV_LOG_ERROR, "can't set v4l2 output format\n");
294  goto error;
295  }
296 
298  if (ret) {
299  av_log(log_ctx, AV_LOG_ERROR, "can't to set v4l2 capture format\n");
300  goto error;
301  }
302 
303  ret = ff_v4l2_context_init(&s->output);
304  if (ret) {
305  av_log(log_ctx, AV_LOG_ERROR, "no v4l2 output context's buffers\n");
306  goto error;
307  }
308 
309  /* decoder's buffers need to be updated at a later stage */
310  if (s->avctx && !av_codec_is_decoder(s->avctx->codec)) {
311  ret = ff_v4l2_context_init(&s->capture);
312  if (ret) {
313  av_log(log_ctx, AV_LOG_ERROR, "no v4l2 capture context's buffers\n");
314  goto error;
315  }
316  }
317 
318  return 0;
319 
320 error:
321  return ret;
322 }
323 
324 static void v4l2_m2m_destroy_context(void *opaque, uint8_t *context)
325 {
326  V4L2m2mContext *s = (V4L2m2mContext*)context;
327 
329  sem_destroy(&s->refsync);
330 
331  close(s->fd);
332  av_frame_unref(s->frame);
333  av_frame_free(&s->frame);
335 
336  av_free(s);
337 }
338 
340 {
341  V4L2m2mContext *s = priv->context;
342  int ret;
343 
344  if (!s)
345  return 0;
346 
347  if (s->fd >= 0) {
348  ret = ff_v4l2_context_set_status(&s->output, VIDIOC_STREAMOFF);
349  if (ret)
350  av_log(s->avctx, AV_LOG_ERROR, "VIDIOC_STREAMOFF %s\n", s->output.name);
351 
352  ret = ff_v4l2_context_set_status(&s->capture, VIDIOC_STREAMOFF);
353  if (ret)
354  av_log(s->avctx, AV_LOG_ERROR, "VIDIOC_STREAMOFF %s\n", s->capture.name);
355  }
356 
358 
359  s->self_ref = NULL;
361 
362  return 0;
363 }
364 
366 {
367  int ret = AVERROR(EINVAL);
368  struct dirent *entry;
369  DIR *dirp;
370 
371  V4L2m2mContext *s = priv->context;
372 
373  dirp = opendir("/dev");
374  if (!dirp)
375  return AVERROR(errno);
376 
377  for (entry = readdir(dirp); entry; entry = readdir(dirp)) {
378 
379  if (strncmp(entry->d_name, "video", 5))
380  continue;
381 
382  snprintf(s->devname, sizeof(s->devname), "/dev/%s", entry->d_name);
383  av_log(s->avctx, AV_LOG_DEBUG, "probing device %s\n", s->devname);
384  ret = v4l2_probe_driver(s);
385  if (!ret)
386  break;
387  }
388 
389  closedir(dirp);
390 
391  if (ret) {
392  av_log(s->avctx, AV_LOG_ERROR, "Could not find a valid device\n");
393  memset(s->devname, 0, sizeof(s->devname));
394 
395  return ret;
396  }
397 
398  av_log(s->avctx, AV_LOG_INFO, "Using device %s\n", s->devname);
399 
400  return v4l2_configure_contexts(s);
401 }
402 
404 {
405  *s = av_mallocz(sizeof(V4L2m2mContext));
406  if (!*s)
407  return AVERROR(ENOMEM);
408 
409  priv->context_ref = av_buffer_create((uint8_t *) *s, sizeof(V4L2m2mContext),
411  if (!priv->context_ref) {
412  av_freep(s);
413  return AVERROR(ENOMEM);
414  }
415 
416  /* assign the context */
417  priv->context = *s;
418  (*s)->priv = priv;
419 
420  /* populate it */
423  priv->context->self_ref = priv->context_ref;
424  priv->context->fd = -1;
425 
426  priv->context->frame = av_frame_alloc();
427  if (!priv->context->frame) {
429  *s = NULL; /* freed when unreferencing context_ref */
430  return AVERROR(ENOMEM);
431  }
432 
433  return 0;
434 }
#define NULL
Definition: coverity.c:32
const struct AVCodec * codec
Definition: avcodec.h:535
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:125
const char * name
context name.
Definition: v4l2_context.h:40
AVCodecContext * avctx
Definition: v4l2_m2m.h:52
misc image utilities
int ff_v4l2_context_init(V4L2Context *ctx)
Initializes a V4L2Context.
Definition: v4l2_context.c:722
int av_codec_is_decoder(const AVCodec *codec)
Definition: utils.c:101
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:237
int ff_v4l2_m2m_codec_end(V4L2m2mPriv *priv)
Releases all the codec resources if all AVBufferRefs have been returned to the ctx.
Definition: v4l2_m2m.c:339
static void error(const char *err)
void ff_v4l2_context_release(V4L2Context *ctx)
Releases a V4L2Context.
Definition: v4l2_context.c:708
int ff_v4l2_context_set_format(V4L2Context *ctx)
Sets the V4L2Context format in the v4l2 driver.
Definition: v4l2_context.c:703
int ff_v4l2_context_get_format(V4L2Context *ctx, int probe)
Queries the driver for a valid v4l2 format and copies it to the context.
Definition: v4l2_context.c:676
int ff_v4l2_m2m_codec_init(V4L2m2mPriv *priv)
Probes the video nodes looking for the required codec capabilities.
Definition: v4l2_m2m.c:365
int ff_v4l2_m2m_create_context(V4L2m2mPriv *priv, V4L2m2mContext **s)
Allocate a new context and references for a V4L2 M2M instance.
Definition: v4l2_m2m.c:403
uint8_t
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:190
#define sem_init
Definition: semaphore.h:40
int ff_v4l2_m2m_codec_reinit(V4L2m2mContext *s)
Reinitializes the V4L2m2mContext when the driver cannot continue processing with the capture paramete...
Definition: v4l2_m2m.c:205
#define av_log(a,...)
int done
Either no more buffers available or an unrecoverable error was notified by the V4L2 kernel driver: on...
Definition: v4l2_context.h:93
static int v4l2_probe_driver(V4L2m2mContext *s)
Definition: v4l2_m2m.c:100
static void v4l2_m2m_destroy_context(void *opaque, uint8_t *context)
Definition: v4l2_m2m.c:324
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
#define atomic_load(object)
Definition: stdatomic.h:93
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:203
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:215
#define av_fourcc2str(fourcc)
Definition: avutil.h:348
#define sem_destroy(psem)
Definition: semaphore.h:29
V4L2m2mContext * context
Definition: v4l2_m2m.h:74
AVBufferRef * av_buffer_create(uint8_t *data, int size, void(*free)(void *opaque, uint8_t *data), void *opaque, int flags)
Create an AVBuffer from an existing array.
Definition: buffer.c:29
AVFrame * frame
Definition: v4l2_m2m.h:62
char devname[PATH_MAX]
Definition: v4l2_m2m.h:44
int num_output_buffers
Definition: v4l2_m2m.h:77
#define av_err2str(errnum)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: error.h:119
#define s(width, name)
Definition: cbs_vp9.c:257
struct v4l2_format format
Format returned by the driver after initializing the buffer context.
Definition: v4l2_context.h:65
int ff_v4l2_context_set_status(V4L2Context *ctx, uint32_t cmd)
Sets the status of a V4L2Context.
Definition: v4l2_context.c:572
#define AV_LOG_INFO
Standard information.
Definition: log.h:205
V4L2Context capture
Definition: v4l2_m2m.h:48
Libavcodec external API header.
atomic_uint refcount
Definition: v4l2_m2m.h:54
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:606
int ff_v4l2_m2m_codec_full_reinit(V4L2m2mContext *s)
Reinitializes the V4L2m2mContext when the driver cannot continue processing with the any of the curre...
Definition: v4l2_m2m.c:248
static int v4l2_configure_contexts(V4L2m2mContext *s)
Definition: v4l2_m2m.c:136
#define snprintf
Definition: snprintf.h:34
static int v4l2_splane_video(struct v4l2_capability *cap)
Definition: v4l2_m2m.c:39
AVPacket buf_pkt
Definition: v4l2_m2m.h:59
void av_frame_unref(AVFrame *frame)
Unreference all the buffers referenced by frame and reset the frame fields.
Definition: frame.c:566
V4L2Context output
Definition: v4l2_m2m.h:49
static int probe(const AVProbeData *p)
Definition: act.c:36
common internal api header.
static int v4l2_prepare_contexts(V4L2m2mContext *s, int probe)
Definition: v4l2_m2m.c:63
int num_capture_buffers
Definition: v4l2_m2m.h:78
AVBufferRef * self_ref
Definition: v4l2_m2m.h:65
pixel format definitions
#define av_free(p)
#define sem_wait(psem)
Definition: semaphore.h:27
int num_buffers
Readonly after init.
Definition: v4l2_context.h:82
#define atomic_init(obj, value)
Definition: stdatomic.h:33
#define av_freep(p)
AVBufferRef * context_ref
Definition: v4l2_m2m.h:75
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
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 default minimum maximum flags name is the option keep it simple and lowercase description are in without and describe what they for example set the foo of the bar offset is the offset of the field in your local context
sem_t refsync
Definition: v4l2_m2m.h:53
enum v4l2_buf_type type
Type of this buffer context.
Definition: v4l2_context.h:47
static int v4l2_mplane_video(struct v4l2_capability *cap)
Definition: v4l2_m2m.c:51