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/%s capture=%s/%s\n",
152  av_fourcc2str(V4L2_TYPE_IS_MULTIPLANAR(ofmt.type) ?
153  ofmt.fmt.pix_mp.pixelformat :
154  ofmt.fmt.pix.pixelformat),
155  av_get_pix_fmt_name(s->output.av_pix_fmt) ?: "none",
156  av_fourcc2str(V4L2_TYPE_IS_MULTIPLANAR(cfmt.type) ?
157  cfmt.fmt.pix_mp.pixelformat :
158  cfmt.fmt.pix.pixelformat),
159  av_get_pix_fmt_name(s->capture.av_pix_fmt) ?: "none");
160 
161  ret = ff_v4l2_context_set_format(&s->output);
162  if (ret) {
163  av_log(log_ctx, AV_LOG_ERROR, "can't set v4l2 output format\n");
164  goto error;
165  }
166 
167  ret = ff_v4l2_context_set_format(&s->capture);
168  if (ret) {
169  av_log(log_ctx, AV_LOG_ERROR, "can't to set v4l2 capture format\n");
170  goto error;
171  }
172 
173  ret = ff_v4l2_context_init(&s->output);
174  if (ret) {
175  av_log(log_ctx, AV_LOG_ERROR, "no v4l2 output context's buffers\n");
176  goto error;
177  }
178 
179  /* decoder's buffers need to be updated at a later stage */
180  if (s->avctx && !av_codec_is_decoder(s->avctx->codec)) {
181  ret = ff_v4l2_context_init(&s->capture);
182  if (ret) {
183  av_log(log_ctx, AV_LOG_ERROR, "no v4l2 capture context's buffers\n");
184  goto error;
185  }
186  }
187 
188  return 0;
189 
190 error:
191  if (close(s->fd) < 0) {
192  ret = AVERROR(errno);
193  av_log(log_ctx, AV_LOG_ERROR, "error closing %s (%s)\n",
194  s->devname, av_err2str(AVERROR(errno)));
195  }
196  s->fd = -1;
197 
198  return ret;
199 }
200 
201 /******************************************************************************
202  *
203  * V4L2 M2M Interface
204  *
205  ******************************************************************************/
207 {
208  void *log_ctx = s->avctx;
209  int ret;
210 
211  av_log(log_ctx, AV_LOG_DEBUG, "reinit context\n");
212 
213  /* 1. streamoff */
214  ret = ff_v4l2_context_set_status(&s->capture, VIDIOC_STREAMOFF);
215  if (ret)
216  av_log(log_ctx, AV_LOG_ERROR, "capture VIDIOC_STREAMOFF\n");
217 
218  /* 2. unmap the capture buffers (v4l2 and ffmpeg):
219  * we must wait for all references to be released before being allowed
220  * to queue new buffers.
221  */
222  av_log(log_ctx, AV_LOG_DEBUG, "waiting for user to release AVBufferRefs\n");
223  if (atomic_load(&s->refcount))
224  while(sem_wait(&s->refsync) == -1 && errno == EINTR);
225 
226  ff_v4l2_context_release(&s->capture);
227 
228  /* 3. get the new capture format */
229  ret = ff_v4l2_context_get_format(&s->capture, 0);
230  if (ret) {
231  av_log(log_ctx, AV_LOG_ERROR, "query the new capture format\n");
232  return ret;
233  }
234 
235  /* 4. set the capture format */
236  ret = ff_v4l2_context_set_format(&s->capture);
237  if (ret) {
238  av_log(log_ctx, AV_LOG_ERROR, "setting capture format\n");
239  return ret;
240  }
241 
242  /* 5. complete reinit */
243  s->draining = 0;
244  s->reinit = 0;
245 
246  return 0;
247 }
248 
249 static void v4l2_m2m_destroy_context(void *opaque, uint8_t *context)
250 {
252 
253  ff_v4l2_context_release(&s->capture);
254  sem_destroy(&s->refsync);
255 
256  if (s->fd >= 0)
257  close(s->fd);
258  av_frame_free(&s->frame);
259  av_packet_unref(&s->buf_pkt);
260 
261  av_free(s);
262 }
263 
265 {
266  V4L2m2mContext *s = priv->context;
267  int ret;
268 
269  if (!s)
270  return 0;
271 
272  if (s->fd >= 0) {
273  ret = ff_v4l2_context_set_status(&s->output, VIDIOC_STREAMOFF);
274  if (ret)
275  av_log(s->avctx, AV_LOG_ERROR, "VIDIOC_STREAMOFF %s\n", s->output.name);
276 
277  ret = ff_v4l2_context_set_status(&s->capture, VIDIOC_STREAMOFF);
278  if (ret)
279  av_log(s->avctx, AV_LOG_ERROR, "VIDIOC_STREAMOFF %s\n", s->capture.name);
280  }
281 
282  ff_v4l2_context_release(&s->output);
283 
284  s->self_ref = NULL;
286 
287  return 0;
288 }
289 
291 {
292  int ret = AVERROR(EINVAL);
293  struct dirent *entry;
294  DIR *dirp;
295 
296  V4L2m2mContext *s = priv->context;
297 
298  dirp = opendir("/dev");
299  if (!dirp)
300  return AVERROR(errno);
301 
302  for (entry = readdir(dirp); entry; entry = readdir(dirp)) {
303 
304  if (strncmp(entry->d_name, "video", 5))
305  continue;
306 
307  snprintf(s->devname, sizeof(s->devname), "/dev/%s", entry->d_name);
308  av_log(s->avctx, AV_LOG_DEBUG, "probing device %s\n", s->devname);
310  if (!ret)
311  break;
312  }
313 
314  closedir(dirp);
315 
316  if (ret) {
317  av_log(s->avctx, AV_LOG_ERROR, "Could not find a valid device\n");
318  memset(s->devname, 0, sizeof(s->devname));
319 
320  return ret;
321  }
322 
323  av_log(s->avctx, AV_LOG_INFO, "Using device %s\n", s->devname);
324 
325  return v4l2_configure_contexts(s);
326 }
327 
329 {
330  *s = av_mallocz(sizeof(V4L2m2mContext));
331  if (!*s)
332  return AVERROR(ENOMEM);
333 
334  priv->context_ref = av_buffer_create((uint8_t *) *s, sizeof(V4L2m2mContext),
336  if (!priv->context_ref) {
337  av_freep(s);
338  return AVERROR(ENOMEM);
339  }
340 
341  /* assign the context */
342  priv->context = *s;
343  (*s)->priv = priv;
344 
345  /* populate it */
348  priv->context->self_ref = priv->context_ref;
349  priv->context->fd = -1;
350 
351  priv->context->frame = av_frame_alloc();
352  if (!priv->context->frame) {
354  *s = NULL; /* freed when unreferencing context_ref */
355  return AVERROR(ENOMEM);
356  }
357 
358  return 0;
359 }
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:712
av_packet_unref
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:427
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:206
V4L2m2mContext
Definition: v4l2_m2m.h:43
av_frame_free
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:100
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.
Definition: v4l2_context.c:698
v4l2_probe_driver
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Definition: v4l2_m2m.c:99
V4L2m2mPriv::context
V4L2m2mContext * context
Definition: v4l2_m2m.h:74
av_frame_alloc
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Allocate an AVFrame and set its fields to default values.
Definition: frame.c:88
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:693
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static int v4l2_splane_video(struct v4l2_capability *cap)
Definition: v4l2_m2m.c:38
ff_v4l2_context_get_format
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Queries the driver for a valid v4l2 format and copies it to the context.
Definition: v4l2_context.c:666
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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:249
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int ff_v4l2_m2m_codec_init(V4L2m2mPriv *priv)
Probes the video nodes looking for the required codec capabilities.
Definition: v4l2_m2m.c:290
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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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static int v4l2_configure_contexts(V4L2m2mContext *s)
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:328
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Definition: v4l2_m2m.h:49
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Definition: buffer.c:55
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Definition: utils.c:86
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Definition: v4l2_m2m.c:264
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