2 * Video4Linux2 grab interface
3 * Copyright (c) 2000,2001 Fabrice Bellard
4 * Copyright (c) 2006 Luca Abeni
6 * Part of this file is based on the V4L2 video capture example
7 * (http://v4l2spec.bytesex.org/v4l2spec/capture.c)
9 * Thanks to Michael Niedermayer for providing the mapping between
10 * V4L2_PIX_FMT_* and PIX_FMT_*
13 * This file is part of Libav.
15 * Libav is free software; you can redistribute it and/or
16 * modify it under the terms of the GNU Lesser General Public
17 * License as published by the Free Software Foundation; either
18 * version 2.1 of the License, or (at your option) any later version.
20 * Libav is distributed in the hope that it will be useful,
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
23 * Lesser General Public License for more details.
25 * You should have received a copy of the GNU Lesser General Public
26 * License along with Libav; if not, write to the Free Software
27 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
30 #undef __STRICT_ANSI__ //workaround due to broken kernel headers
32 #include "libavformat/avformat.h"
35 #include <sys/ioctl.h>
38 #if HAVE_SYS_VIDEOIO_H
39 #include <sys/videoio.h>
41 #include <asm/types.h>
42 #include <linux/videodev2.h>
46 #include "libavutil/imgutils.h"
47 #include "libavutil/log.h"
48 #include "libavutil/opt.h"
49 #include "libavutil/parseutils.h"
50 #include "libavutil/pixdesc.h"
52 static const int desired_video_buffers = 256;
63 int frame_format; /* V4L2_PIX_FMT_* */
64 enum io_method io_method;
71 unsigned int *buf_len;
74 char *video_size; /**< String describing video size, set by a private option. */
75 char *pixel_format; /**< Set by a private option. */
76 char *framerate; /**< Set by a private option. */
85 enum PixelFormat ff_fmt;
86 enum CodecID codec_id;
90 static struct fmt_map fmt_conversion_table[] = {
91 //ff_fmt codec_id v4l2_fmt
92 { PIX_FMT_YUV420P, CODEC_ID_RAWVIDEO, V4L2_PIX_FMT_YUV420 },
93 { PIX_FMT_YUV422P, CODEC_ID_RAWVIDEO, V4L2_PIX_FMT_YUV422P },
94 { PIX_FMT_YUYV422, CODEC_ID_RAWVIDEO, V4L2_PIX_FMT_YUYV },
95 { PIX_FMT_UYVY422, CODEC_ID_RAWVIDEO, V4L2_PIX_FMT_UYVY },
96 { PIX_FMT_YUV411P, CODEC_ID_RAWVIDEO, V4L2_PIX_FMT_YUV411P },
97 { PIX_FMT_YUV410P, CODEC_ID_RAWVIDEO, V4L2_PIX_FMT_YUV410 },
98 { PIX_FMT_RGB555, CODEC_ID_RAWVIDEO, V4L2_PIX_FMT_RGB555 },
99 { PIX_FMT_RGB565, CODEC_ID_RAWVIDEO, V4L2_PIX_FMT_RGB565 },
100 { PIX_FMT_BGR24, CODEC_ID_RAWVIDEO, V4L2_PIX_FMT_BGR24 },
101 { PIX_FMT_RGB24, CODEC_ID_RAWVIDEO, V4L2_PIX_FMT_RGB24 },
102 { PIX_FMT_BGRA, CODEC_ID_RAWVIDEO, V4L2_PIX_FMT_BGR32 },
103 { PIX_FMT_GRAY8, CODEC_ID_RAWVIDEO, V4L2_PIX_FMT_GREY },
104 { PIX_FMT_NV12, CODEC_ID_RAWVIDEO, V4L2_PIX_FMT_NV12 },
105 { PIX_FMT_NONE, CODEC_ID_MJPEG, V4L2_PIX_FMT_MJPEG },
106 { PIX_FMT_NONE, CODEC_ID_MJPEG, V4L2_PIX_FMT_JPEG },
109 static int device_open(AVFormatContext *ctx, uint32_t *capabilities)
111 struct v4l2_capability cap;
116 if (ctx->flags & AVFMT_FLAG_NONBLOCK) {
119 fd = open(ctx->filename, flags, 0);
121 av_log(ctx, AV_LOG_ERROR, "Cannot open video device %s : %s\n",
122 ctx->filename, strerror(errno));
124 return AVERROR(errno);
127 res = ioctl(fd, VIDIOC_QUERYCAP, &cap);
128 // ENOIOCTLCMD definition only availble on __KERNEL__
129 if (res < 0 && ((err = errno) == 515)) {
130 av_log(ctx, AV_LOG_ERROR, "QUERYCAP not implemented, probably V4L device but not supporting V4L2\n");
136 av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_QUERYCAP): %s\n",
142 if ((cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) == 0) {
143 av_log(ctx, AV_LOG_ERROR, "Not a video capture device\n");
146 return AVERROR(ENODEV);
148 *capabilities = cap.capabilities;
153 static int device_init(AVFormatContext *ctx, int *width, int *height, uint32_t pix_fmt)
155 struct video_data *s = ctx->priv_data;
157 struct v4l2_format fmt;
160 memset(&fmt, 0, sizeof(struct v4l2_format));
161 fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
162 fmt.fmt.pix.width = *width;
163 fmt.fmt.pix.height = *height;
164 fmt.fmt.pix.pixelformat = pix_fmt;
165 fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
166 res = ioctl(fd, VIDIOC_S_FMT, &fmt);
167 if ((*width != fmt.fmt.pix.width) || (*height != fmt.fmt.pix.height)) {
168 av_log(ctx, AV_LOG_INFO, "The V4L2 driver changed the video from %dx%d to %dx%d\n", *width, *height, fmt.fmt.pix.width, fmt.fmt.pix.height);
169 *width = fmt.fmt.pix.width;
170 *height = fmt.fmt.pix.height;
173 if (pix_fmt != fmt.fmt.pix.pixelformat) {
174 av_log(ctx, AV_LOG_DEBUG, "The V4L2 driver changed the pixel format from 0x%08X to 0x%08X\n", pix_fmt, fmt.fmt.pix.pixelformat);
181 static int first_field(int fd)
186 res = ioctl(fd, VIDIOC_G_STD, &std);
190 if (std & V4L2_STD_NTSC) {
197 static uint32_t fmt_ff2v4l(enum PixelFormat pix_fmt, enum CodecID codec_id)
201 for (i = 0; i < FF_ARRAY_ELEMS(fmt_conversion_table); i++) {
202 if ((codec_id == CODEC_ID_NONE ||
203 fmt_conversion_table[i].codec_id == codec_id) &&
204 (pix_fmt == PIX_FMT_NONE ||
205 fmt_conversion_table[i].ff_fmt == pix_fmt)) {
206 return fmt_conversion_table[i].v4l2_fmt;
213 static enum PixelFormat fmt_v4l2ff(uint32_t v4l2_fmt, enum CodecID codec_id)
217 for (i = 0; i < FF_ARRAY_ELEMS(fmt_conversion_table); i++) {
218 if (fmt_conversion_table[i].v4l2_fmt == v4l2_fmt &&
219 fmt_conversion_table[i].codec_id == codec_id) {
220 return fmt_conversion_table[i].ff_fmt;
227 static enum CodecID fmt_v4l2codec(uint32_t v4l2_fmt)
231 for (i = 0; i < FF_ARRAY_ELEMS(fmt_conversion_table); i++) {
232 if (fmt_conversion_table[i].v4l2_fmt == v4l2_fmt) {
233 return fmt_conversion_table[i].codec_id;
237 return CODEC_ID_NONE;
240 static int mmap_init(AVFormatContext *ctx)
242 struct video_data *s = ctx->priv_data;
243 struct v4l2_requestbuffers req;
246 memset(&req, 0, sizeof(struct v4l2_requestbuffers));
247 req.count = desired_video_buffers;
248 req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
249 req.memory = V4L2_MEMORY_MMAP;
250 res = ioctl(s->fd, VIDIOC_REQBUFS, &req);
252 if (errno == EINVAL) {
253 av_log(ctx, AV_LOG_ERROR, "Device does not support mmap\n");
255 av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_REQBUFS)\n");
258 return AVERROR(errno);
262 av_log(ctx, AV_LOG_ERROR, "Insufficient buffer memory\n");
264 return AVERROR(ENOMEM);
266 s->buffers = req.count;
267 s->buf_start = av_malloc(sizeof(void *) * s->buffers);
268 if (s->buf_start == NULL) {
269 av_log(ctx, AV_LOG_ERROR, "Cannot allocate buffer pointers\n");
271 return AVERROR(ENOMEM);
273 s->buf_len = av_malloc(sizeof(unsigned int) * s->buffers);
274 if (s->buf_len == NULL) {
275 av_log(ctx, AV_LOG_ERROR, "Cannot allocate buffer sizes\n");
276 av_free(s->buf_start);
278 return AVERROR(ENOMEM);
281 for (i = 0; i < req.count; i++) {
282 struct v4l2_buffer buf;
284 memset(&buf, 0, sizeof(struct v4l2_buffer));
285 buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
286 buf.memory = V4L2_MEMORY_MMAP;
288 res = ioctl(s->fd, VIDIOC_QUERYBUF, &buf);
290 av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_QUERYBUF)\n");
292 return AVERROR(errno);
295 s->buf_len[i] = buf.length;
296 if (s->frame_size > 0 && s->buf_len[i] < s->frame_size) {
297 av_log(ctx, AV_LOG_ERROR, "Buffer len [%d] = %d != %d\n", i, s->buf_len[i], s->frame_size);
301 s->buf_start[i] = mmap (NULL, buf.length,
302 PROT_READ | PROT_WRITE, MAP_SHARED, s->fd, buf.m.offset);
303 if (s->buf_start[i] == MAP_FAILED) {
304 av_log(ctx, AV_LOG_ERROR, "mmap: %s\n", strerror(errno));
306 return AVERROR(errno);
313 static int read_init(AVFormatContext *ctx)
318 static void mmap_release_buffer(AVPacket *pkt)
320 struct v4l2_buffer buf;
322 struct buff_data *buf_descriptor = pkt->priv;
324 if (pkt->data == NULL) {
328 memset(&buf, 0, sizeof(struct v4l2_buffer));
329 buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
330 buf.memory = V4L2_MEMORY_MMAP;
331 buf.index = buf_descriptor->index;
332 fd = buf_descriptor->fd;
333 av_free(buf_descriptor);
335 res = ioctl(fd, VIDIOC_QBUF, &buf);
337 av_log(NULL, AV_LOG_ERROR, "ioctl(VIDIOC_QBUF): %s\n", strerror(errno));
343 static int mmap_read_frame(AVFormatContext *ctx, AVPacket *pkt)
345 struct video_data *s = ctx->priv_data;
346 struct v4l2_buffer buf;
347 struct buff_data *buf_descriptor;
350 memset(&buf, 0, sizeof(struct v4l2_buffer));
351 buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
352 buf.memory = V4L2_MEMORY_MMAP;
354 /* FIXME: Some special treatment might be needed in case of loss of signal... */
355 while ((res = ioctl(s->fd, VIDIOC_DQBUF, &buf)) < 0 && (errno == EINTR));
357 if (errno == EAGAIN) {
360 return AVERROR(EAGAIN);
362 av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_DQBUF): %s\n", strerror(errno));
364 return AVERROR(errno);
366 assert (buf.index < s->buffers);
367 if (s->frame_size > 0 && buf.bytesused != s->frame_size) {
368 av_log(ctx, AV_LOG_ERROR, "The v4l2 frame is %d bytes, but %d bytes are expected\n", buf.bytesused, s->frame_size);
370 return AVERROR_INVALIDDATA;
373 /* Image is at s->buff_start[buf.index] */
374 pkt->data= s->buf_start[buf.index];
375 pkt->size = buf.bytesused;
376 pkt->pts = buf.timestamp.tv_sec * INT64_C(1000000) + buf.timestamp.tv_usec;
377 pkt->destruct = mmap_release_buffer;
378 buf_descriptor = av_malloc(sizeof(struct buff_data));
379 if (buf_descriptor == NULL) {
380 /* Something went wrong... Since av_malloc() failed, we cannot even
381 * allocate a buffer for memcopying into it
383 av_log(ctx, AV_LOG_ERROR, "Failed to allocate a buffer descriptor\n");
384 res = ioctl(s->fd, VIDIOC_QBUF, &buf);
386 return AVERROR(ENOMEM);
388 buf_descriptor->fd = s->fd;
389 buf_descriptor->index = buf.index;
390 pkt->priv = buf_descriptor;
392 return s->buf_len[buf.index];
395 static int read_frame(AVFormatContext *ctx, AVPacket *pkt)
400 static int mmap_start(AVFormatContext *ctx)
402 struct video_data *s = ctx->priv_data;
403 enum v4l2_buf_type type;
406 for (i = 0; i < s->buffers; i++) {
407 struct v4l2_buffer buf;
409 memset(&buf, 0, sizeof(struct v4l2_buffer));
410 buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
411 buf.memory = V4L2_MEMORY_MMAP;
414 res = ioctl(s->fd, VIDIOC_QBUF, &buf);
416 av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_QBUF): %s\n", strerror(errno));
418 return AVERROR(errno);
422 type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
423 res = ioctl(s->fd, VIDIOC_STREAMON, &type);
425 av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_STREAMON): %s\n", strerror(errno));
427 return AVERROR(errno);
433 static void mmap_close(struct video_data *s)
435 enum v4l2_buf_type type;
438 type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
439 /* We do not check for the result, because we could
440 * not do anything about it anyway...
442 ioctl(s->fd, VIDIOC_STREAMOFF, &type);
443 for (i = 0; i < s->buffers; i++) {
444 munmap(s->buf_start[i], s->buf_len[i]);
446 av_free(s->buf_start);
450 static int v4l2_set_parameters(AVFormatContext *s1, AVFormatParameters *ap)
452 struct video_data *s = s1->priv_data;
453 struct v4l2_input input;
454 struct v4l2_standard standard;
455 struct v4l2_streamparm streamparm = { 0 };
456 struct v4l2_fract *tpf = &streamparm.parm.capture.timeperframe;
460 streamparm.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
462 if (s->framerate && (ret = av_parse_video_rate(&fps, s->framerate)) < 0) {
463 av_log(s1, AV_LOG_ERROR, "Couldn't parse framerate.\n");
466 #if FF_API_FORMAT_PARAMETERS
468 s->channel = ap->channel;
469 if (ap->time_base.num)
470 fps = (AVRational){ap->time_base.den, ap->time_base.num};
473 /* set tv video input */
474 memset (&input, 0, sizeof (input));
475 input.index = s->channel;
476 if (ioctl(s->fd, VIDIOC_ENUMINPUT, &input) < 0) {
477 av_log(s1, AV_LOG_ERROR, "The V4L2 driver ioctl enum input failed:\n");
481 av_log(s1, AV_LOG_DEBUG, "The V4L2 driver set input_id: %d, input: %s\n",
482 s->channel, input.name);
483 if (ioctl(s->fd, VIDIOC_S_INPUT, &input.index) < 0) {
484 av_log(s1, AV_LOG_ERROR, "The V4L2 driver ioctl set input(%d) failed\n",
489 #if FF_API_FORMAT_PARAMETERS
491 av_freep(&s->standard);
492 s->standard = av_strdup(ap->standard);
497 av_log(s1, AV_LOG_DEBUG, "The V4L2 driver set standard: %s\n",
499 /* set tv standard */
500 memset (&standard, 0, sizeof (standard));
503 if (ioctl(s->fd, VIDIOC_ENUMSTD, &standard) < 0) {
504 av_log(s1, AV_LOG_ERROR, "The V4L2 driver ioctl set standard(%s) failed\n",
509 if (!strcasecmp(standard.name, s->standard)) {
514 av_log(s1, AV_LOG_DEBUG, "The V4L2 driver set standard: %s, id: %"PRIu64"\n",
515 s->standard, (uint64_t)standard.id);
516 if (ioctl(s->fd, VIDIOC_S_STD, &standard.id) < 0) {
517 av_log(s1, AV_LOG_ERROR, "The V4L2 driver ioctl set standard(%s) failed\n",
523 if (fps.num && fps.den) {
524 av_log(s1, AV_LOG_DEBUG, "Setting time per frame to %d/%d\n",
526 tpf->numerator = fps.den;
527 tpf->denominator = fps.num;
528 if (ioctl(s->fd, VIDIOC_S_PARM, &streamparm) != 0) {
529 av_log(s1, AV_LOG_ERROR,
530 "ioctl set time per frame(%d/%d) failed\n",
535 if (fps.num != tpf->denominator ||
536 fps.den != tpf->numerator) {
537 av_log(s1, AV_LOG_INFO,
538 "The driver changed the time per frame from %d/%d to %d/%d\n",
540 tpf->numerator, tpf->denominator);
543 /* if timebase value is not set, read the timebase value from the driver */
544 if (ioctl(s->fd, VIDIOC_G_PARM, &streamparm) != 0) {
545 av_log(s1, AV_LOG_ERROR, "ioctl(VIDIOC_G_PARM): %s\n", strerror(errno));
546 return AVERROR(errno);
549 s1->streams[0]->codec->time_base.den = tpf->denominator;
550 s1->streams[0]->codec->time_base.num = tpf->numerator;
555 static uint32_t device_try_init(AVFormatContext *s1,
556 enum PixelFormat pix_fmt,
559 enum CodecID *codec_id)
561 uint32_t desired_format = fmt_ff2v4l(pix_fmt, s1->video_codec_id);
563 if (desired_format == 0 ||
564 device_init(s1, width, height, desired_format) < 0) {
568 for (i = 0; i<FF_ARRAY_ELEMS(fmt_conversion_table); i++) {
569 if (s1->video_codec_id == CODEC_ID_NONE ||
570 fmt_conversion_table[i].codec_id == s1->video_codec_id) {
571 desired_format = fmt_conversion_table[i].v4l2_fmt;
572 if (device_init(s1, width, height, desired_format) >= 0) {
579 if (desired_format != 0) {
580 *codec_id = fmt_v4l2codec(desired_format);
581 assert(*codec_id != CODEC_ID_NONE);
584 return desired_format;
587 static int v4l2_read_header(AVFormatContext *s1, AVFormatParameters *ap)
589 struct video_data *s = s1->priv_data;
592 uint32_t desired_format, capabilities;
593 enum CodecID codec_id;
594 enum PixelFormat pix_fmt = PIX_FMT_NONE;
596 st = av_new_stream(s1, 0);
598 res = AVERROR(ENOMEM);
601 av_set_pts_info(st, 64, 1, 1000000); /* 64 bits pts in us */
603 if (s->video_size && (res = av_parse_video_size(&s->width, &s->height, s->video_size)) < 0) {
604 av_log(s1, AV_LOG_ERROR, "Couldn't parse video size.\n");
607 if (s->pixel_format && (pix_fmt = av_get_pix_fmt(s->pixel_format)) == PIX_FMT_NONE) {
608 av_log(s1, AV_LOG_ERROR, "No such pixel format: %s.\n", s->pixel_format);
609 res = AVERROR(EINVAL);
612 #if FF_API_FORMAT_PARAMETERS
614 s->width = ap->width;
616 s->height = ap->height;
618 pix_fmt = ap->pix_fmt;
622 s->fd = device_open(s1, &capabilities);
627 av_log(s1, AV_LOG_VERBOSE, "[%d]Capabilities: %x\n", s->fd, capabilities);
629 if (!s->width && !s->height) {
630 struct v4l2_format fmt;
632 av_log(s1, AV_LOG_VERBOSE, "Querying the device for the current frame size\n");
633 fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
634 if (ioctl(s->fd, VIDIOC_G_FMT, &fmt) < 0) {
635 av_log(s1, AV_LOG_ERROR, "ioctl(VIDIOC_G_FMT): %s\n", strerror(errno));
636 res = AVERROR(errno);
639 s->width = fmt.fmt.pix.width;
640 s->height = fmt.fmt.pix.height;
641 av_log(s1, AV_LOG_VERBOSE, "Setting frame size to %dx%d\n", s->width, s->height);
644 desired_format = device_try_init(s1, pix_fmt, &s->width, &s->height, &codec_id);
645 if (desired_format == 0) {
646 av_log(s1, AV_LOG_ERROR, "Cannot find a proper format for "
647 "codec_id %d, pix_fmt %d.\n", s1->video_codec_id, pix_fmt);
653 if ((res = av_image_check_size(s->width, s->height, 0, s1) < 0))
655 s->frame_format = desired_format;
657 if ((res = v4l2_set_parameters(s1, ap) < 0))
660 st->codec->pix_fmt = fmt_v4l2ff(desired_format, codec_id);
661 s->frame_size = avpicture_get_size(st->codec->pix_fmt, s->width, s->height);
662 if (capabilities & V4L2_CAP_STREAMING) {
663 s->io_method = io_mmap;
666 res = mmap_start(s1);
669 s->io_method = io_read;
678 s->top_field_first = first_field(s->fd);
680 st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
681 st->codec->codec_id = codec_id;
682 st->codec->width = s->width;
683 st->codec->height = s->height;
684 st->codec->bit_rate = s->frame_size * 1/av_q2d(st->codec->time_base) * 8;
690 static int v4l2_read_packet(AVFormatContext *s1, AVPacket *pkt)
692 struct video_data *s = s1->priv_data;
695 if (s->io_method == io_mmap) {
697 res = mmap_read_frame(s1, pkt);
698 } else if (s->io_method == io_read) {
699 if (av_new_packet(pkt, s->frame_size) < 0)
702 res = read_frame(s1, pkt);
710 if (s1->streams[0]->codec->coded_frame) {
711 s1->streams[0]->codec->coded_frame->interlaced_frame = 1;
712 s1->streams[0]->codec->coded_frame->top_field_first = s->top_field_first;
718 static int v4l2_read_close(AVFormatContext *s1)
720 struct video_data *s = s1->priv_data;
722 if (s->io_method == io_mmap) {
730 #define OFFSET(x) offsetof(struct video_data, x)
731 #define DEC AV_OPT_FLAG_DECODING_PARAM
732 static const AVOption options[] = {
733 { "standard", "", offsetof(struct video_data, standard), FF_OPT_TYPE_STRING, {.str = NULL }, 0, 0, AV_OPT_FLAG_DECODING_PARAM },
734 { "channel", "", offsetof(struct video_data, channel), FF_OPT_TYPE_INT, {.dbl = 0 }, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
735 { "video_size", "A string describing frame size, such as 640x480 or hd720.", OFFSET(video_size), FF_OPT_TYPE_STRING, {.str = NULL}, 0, 0, DEC },
736 { "pixel_format", "", OFFSET(pixel_format), FF_OPT_TYPE_STRING, {.str = NULL}, 0, 0, DEC },
737 { "framerate", "", OFFSET(framerate), FF_OPT_TYPE_STRING, {.str = NULL}, 0, 0, DEC },
741 static const AVClass v4l2_class = {
742 .class_name = "V4L2 indev",
743 .item_name = av_default_item_name,
745 .version = LIBAVUTIL_VERSION_INT,
748 AVInputFormat ff_v4l2_demuxer = {
750 NULL_IF_CONFIG_SMALL("Video4Linux2 device grab"),
751 sizeof(struct video_data),
756 .flags = AVFMT_NOFILE,
757 .priv_class = &v4l2_class,