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 "libavutil/pixdesc.h"
32 #include "libavutil/imgutils.h"
33 #include "libavutil/pixfmt.h"
34 #include "v4l2_context.h"
35 #include "v4l2_fmt.h"
36 #include "v4l2_m2m.h"
37 
38 static inline int v4l2_splane_video(struct v4l2_capability *cap)
39 {
40  if (cap->capabilities & (V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_VIDEO_OUTPUT) &&
41  cap->capabilities & V4L2_CAP_STREAMING)
42  return 1;
43 
44  if (cap->capabilities & V4L2_CAP_VIDEO_M2M)
45  return 1;
46 
47  return 0;
48 }
49 
50 static inline int v4l2_mplane_video(struct v4l2_capability *cap)
51 {
52  if (cap->capabilities & (V4L2_CAP_VIDEO_CAPTURE_MPLANE | V4L2_CAP_VIDEO_OUTPUT_MPLANE) &&
53  cap->capabilities & V4L2_CAP_STREAMING)
54  return 1;
55 
56  if (cap->capabilities & V4L2_CAP_VIDEO_M2M_MPLANE)
57  return 1;
58 
59  return 0;
60 }
61 
63 {
64  struct v4l2_capability cap;
65  void *log_ctx = s->avctx;
66  int ret;
67 
68  s->capture.done = s->output.done = 0;
69  s->capture.name = "capture";
70  s->output.name = "output";
71  atomic_init(&s->refcount, 0);
72  sem_init(&s->refsync, 0, 0);
73 
74  memset(&cap, 0, sizeof(cap));
75  ret = ioctl(s->fd, VIDIOC_QUERYCAP, &cap);
76  if (ret < 0)
77  return ret;
78 
79  av_log(log_ctx, probe ? AV_LOG_DEBUG : AV_LOG_INFO,
80  "driver '%s' on card '%s' in %s mode\n", cap.driver, cap.card,
81  v4l2_mplane_video(&cap) ? "mplane" :
82  v4l2_splane_video(&cap) ? "splane" : "unknown");
83 
84  if (v4l2_mplane_video(&cap)) {
85  s->capture.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
86  s->output.type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
87  return 0;
88  }
89 
90  if (v4l2_splane_video(&cap)) {
91  s->capture.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
92  s->output.type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
93  return 0;
94  }
95 
96  return AVERROR(EINVAL);
97 }
98 
100 {
101  void *log_ctx = s->avctx;
102  int ret;
103 
104  s->fd = open(s->devname, O_RDWR | O_NONBLOCK, 0);
105  if (s->fd < 0)
106  return AVERROR(errno);
107 
109  if (ret < 0)
110  goto done;
111 
112  ret = ff_v4l2_context_get_format(&s->output, 1);
113  if (ret) {
114  av_log(log_ctx, AV_LOG_DEBUG, "v4l2 output format not supported\n");
115  goto done;
116  }
117 
118  ret = ff_v4l2_context_get_format(&s->capture, 1);
119  if (ret) {
120  av_log(log_ctx, AV_LOG_DEBUG, "v4l2 capture format not supported\n");
121  goto done;
122  }
123 
124 done:
125  if (close(s->fd) < 0) {
126  ret = AVERROR(errno);
127  av_log(log_ctx, AV_LOG_ERROR, "failure closing %s (%s)\n", s->devname, av_err2str(AVERROR(errno)));
128  }
129 
130  s->fd = -1;
131 
132  return ret;
133 }
134 
136 {
137  void *log_ctx = s->avctx;
138  int ret;
139  struct v4l2_format ofmt, cfmt;
140 
141  s->fd = open(s->devname, O_RDWR | O_NONBLOCK, 0);
142  if (s->fd < 0)
143  return AVERROR(errno);
144 
146  if (ret < 0)
147  goto error;
148 
149  ofmt = s->output.format;
150  cfmt = s->capture.format;
151  av_log(log_ctx, AV_LOG_INFO, "requesting formats: output=%s capture=%s\n",
152  av_fourcc2str(V4L2_TYPE_IS_MULTIPLANAR(ofmt.type) ?
153  ofmt.fmt.pix_mp.pixelformat :
154  ofmt.fmt.pix.pixelformat),
155  av_fourcc2str(V4L2_TYPE_IS_MULTIPLANAR(cfmt.type) ?
156  cfmt.fmt.pix_mp.pixelformat :
157  cfmt.fmt.pix.pixelformat));
158 
159  ret = ff_v4l2_context_set_format(&s->output);
160  if (ret) {
161  av_log(log_ctx, AV_LOG_ERROR, "can't set v4l2 output format\n");
162  goto error;
163  }
164 
165  ret = ff_v4l2_context_set_format(&s->capture);
166  if (ret) {
167  av_log(log_ctx, AV_LOG_ERROR, "can't to set v4l2 capture format\n");
168  goto error;
169  }
170 
171  ret = ff_v4l2_context_init(&s->output);
172  if (ret) {
173  av_log(log_ctx, AV_LOG_ERROR, "no v4l2 output context's buffers\n");
174  goto error;
175  }
176 
177  /* decoder's buffers need to be updated at a later stage */
178  if (s->avctx && !av_codec_is_decoder(s->avctx->codec)) {
179  ret = ff_v4l2_context_init(&s->capture);
180  if (ret) {
181  av_log(log_ctx, AV_LOG_ERROR, "no v4l2 capture context's buffers\n");
182  goto error;
183  }
184  }
185 
186  return 0;
187 
188 error:
189  if (close(s->fd) < 0) {
190  ret = AVERROR(errno);
191  av_log(log_ctx, AV_LOG_ERROR, "error closing %s (%s)\n",
192  s->devname, av_err2str(AVERROR(errno)));
193  }
194  s->fd = -1;
195 
196  return ret;
197 }
198 
199 /******************************************************************************
200  *
201  * V4L2 M2M Interface
202  *
203  ******************************************************************************/
205 {
206  void *log_ctx = s->avctx;
207  int ret;
208 
209  av_log(log_ctx, AV_LOG_DEBUG, "reinit context\n");
210 
211  /* 1. streamoff */
212  ret = ff_v4l2_context_set_status(&s->capture, VIDIOC_STREAMOFF);
213  if (ret)
214  av_log(log_ctx, AV_LOG_ERROR, "capture VIDIOC_STREAMOFF\n");
215 
216  /* 2. unmap the capture buffers (v4l2 and ffmpeg):
217  * we must wait for all references to be released before being allowed
218  * to queue new buffers.
219  */
220  av_log(log_ctx, AV_LOG_DEBUG, "waiting for user to release AVBufferRefs\n");
221  if (atomic_load(&s->refcount))
222  while(sem_wait(&s->refsync) == -1 && errno == EINTR);
223 
224  ff_v4l2_context_release(&s->capture);
225 
226  /* 3. get the new capture format */
227  ret = ff_v4l2_context_get_format(&s->capture, 0);
228  if (ret) {
229  av_log(log_ctx, AV_LOG_ERROR, "query the new capture format\n");
230  return ret;
231  }
232 
233  /* 4. set the capture format */
234  ret = ff_v4l2_context_set_format(&s->capture);
235  if (ret) {
236  av_log(log_ctx, AV_LOG_ERROR, "setting capture format\n");
237  return ret;
238  }
239 
240  /* 5. complete reinit */
241  s->draining = 0;
242  s->reinit = 0;
243 
244  return 0;
245 }
246 
247 static void v4l2_m2m_destroy_context(void *opaque, uint8_t *context)
248 {
250 
251  ff_v4l2_context_release(&s->capture);
252  sem_destroy(&s->refsync);
253 
254  close(s->fd);
255  av_frame_unref(s->frame);
256  av_frame_free(&s->frame);
257  av_packet_unref(&s->buf_pkt);
258 
259  av_free(s);
260 }
261 
263 {
264  V4L2m2mContext *s = priv->context;
265  int ret;
266 
267  if (!s)
268  return 0;
269 
270  if (s->fd >= 0) {
271  ret = ff_v4l2_context_set_status(&s->output, VIDIOC_STREAMOFF);
272  if (ret)
273  av_log(s->avctx, AV_LOG_ERROR, "VIDIOC_STREAMOFF %s\n", s->output.name);
274 
275  ret = ff_v4l2_context_set_status(&s->capture, VIDIOC_STREAMOFF);
276  if (ret)
277  av_log(s->avctx, AV_LOG_ERROR, "VIDIOC_STREAMOFF %s\n", s->capture.name);
278  }
279 
280  ff_v4l2_context_release(&s->output);
281 
282  s->self_ref = NULL;
284 
285  return 0;
286 }
287 
289 {
290  int ret = AVERROR(EINVAL);
291  struct dirent *entry;
292  DIR *dirp;
293 
294  V4L2m2mContext *s = priv->context;
295 
296  dirp = opendir("/dev");
297  if (!dirp)
298  return AVERROR(errno);
299 
300  for (entry = readdir(dirp); entry; entry = readdir(dirp)) {
301 
302  if (strncmp(entry->d_name, "video", 5))
303  continue;
304 
305  snprintf(s->devname, sizeof(s->devname), "/dev/%s", entry->d_name);
306  av_log(s->avctx, AV_LOG_DEBUG, "probing device %s\n", s->devname);
308  if (!ret)
309  break;
310  }
311 
312  closedir(dirp);
313 
314  if (ret) {
315  av_log(s->avctx, AV_LOG_ERROR, "Could not find a valid device\n");
316  memset(s->devname, 0, sizeof(s->devname));
317 
318  return ret;
319  }
320 
321  av_log(s->avctx, AV_LOG_INFO, "Using device %s\n", s->devname);
322 
323  return v4l2_configure_contexts(s);
324 }
325 
327 {
328  *s = av_mallocz(sizeof(V4L2m2mContext));
329  if (!*s)
330  return AVERROR(ENOMEM);
331 
332  priv->context_ref = av_buffer_create((uint8_t *) *s, sizeof(V4L2m2mContext),
334  if (!priv->context_ref) {
335  av_freep(s);
336  return AVERROR(ENOMEM);
337  }
338 
339  /* assign the context */
340  priv->context = *s;
341  (*s)->priv = priv;
342 
343  /* populate it */
346  priv->context->self_ref = priv->context_ref;
347  priv->context->fd = -1;
348 
349  priv->context->frame = av_frame_alloc();
350  if (!priv->context->frame) {
352  *s = NULL; /* freed when unreferencing context_ref */
353  return AVERROR(ENOMEM);
354  }
355 
356  return 0;
357 }
error
static void error(const char *err)
Definition: target_bsf_fuzzer.c:31
ff_v4l2_context_init
int ff_v4l2_context_init(V4L2Context *ctx)
Initializes a V4L2Context.
Definition: v4l2_context.c:708
av_packet_unref
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:422
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
ff_v4l2_m2m_codec_reinit
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:204
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Definition: v4l2_m2m.h:43
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void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:111
pixdesc.h
v4l2_mplane_video
static int v4l2_mplane_video(struct v4l2_capability *cap)
Definition: v4l2_m2m.c:50
ff_v4l2_context_release
void ff_v4l2_context_release(V4L2Context *ctx)
Releases a V4L2Context.
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Definition: v4l2_m2m.c:99
V4L2m2mPriv::context
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Definition: v4l2_m2m.h:74
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Definition: frame.c:99
AV_LOG_ERROR
#define AV_LOG_ERROR
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Definition: log.h:180
ff_v4l2_context_set_format
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Sets the V4L2Context format in the v4l2 driver.
Definition: v4l2_context.c:689
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static int v4l2_splane_video(struct v4l2_capability *cap)
Definition: v4l2_m2m.c:38
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Queries the driver for a valid v4l2 format and copies it to the context.
Definition: v4l2_context.c:662
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V4L2m2mContext::capture
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Definition: v4l2_m2m.h:48
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Definition: log.h:201
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Definition: v4l2_m2m.c:247
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Probes the video nodes looking for the required codec capabilities.
Definition: v4l2_m2m.c:288
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#define atomic_load(object)
Definition: stdatomic.h:93
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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 context
Definition: writing_filters.txt:91
NULL
#define NULL
Definition: coverity.c:32
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Free a given reference and automatically free the buffer if there are no more references to it.
Definition: buffer.c:139
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Definition: v4l2_m2m.c:135
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Definition: v4l2_m2m.c:62
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Allocate a new context and references for a V4L2 M2M instance.
Definition: v4l2_m2m.c:326
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Definition: v4l2_m2m.c:262
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