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ffmpeg / libavdevice / v4l2.c @ 5d91e928

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1
/*
2
 * Video4Linux2 grab interface
3
 * Copyright (c) 2000,2001 Fabrice Bellard.
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 * Copyright (c) 2006 Luca Abeni.
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 *
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 * Part of this file is based on the V4L2 video capture example
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 * (http://v4l2spec.bytesex.org/v4l2spec/capture.c)
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 *
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 * Thanks to Michael Niedermayer for providing the mapping between
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 * V4L2_PIX_FMT_* and PIX_FMT_*
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 *
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 *
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 * This file is part of FFmpeg.
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 *
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 * FFmpeg is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * FFmpeg is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with FFmpeg; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
29

    
30
#undef __STRICT_ANSI__ //workaround due to broken kernel headers
31
#include "config.h"
32
#include "libavformat/avformat.h"
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <sys/mman.h>
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#include <sys/time.h>
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#ifdef HAVE_SYS_VIDEOIO_H
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#include <sys/videoio.h>
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#else
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#include <asm/types.h>
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#include <linux/videodev2.h>
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#endif
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#include <time.h>
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#include <strings.h>
46

    
47
static const int desired_video_buffers = 256;
48

    
49
enum io_method {
50
    io_read,
51
    io_mmap,
52
    io_userptr
53
};
54

    
55
struct video_data {
56
    int fd;
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    int frame_format; /* V4L2_PIX_FMT_* */
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    enum io_method io_method;
59
    int width, height;
60
    int frame_rate;
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    int frame_rate_base;
62
    int frame_size;
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    int top_field_first;
64

    
65
    int buffers;
66
    void **buf_start;
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    unsigned int *buf_len;
68
};
69

    
70
struct buff_data {
71
    int index;
72
    int fd;
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};
74

    
75
struct fmt_map {
76
    enum PixelFormat ff_fmt;
77
    int32_t v4l2_fmt;
78
};
79

    
80
static struct fmt_map fmt_conversion_table[] = {
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    {
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        .ff_fmt = PIX_FMT_YUV420P,
83
        .v4l2_fmt = V4L2_PIX_FMT_YUV420,
84
    },
85
    {
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        .ff_fmt = PIX_FMT_YUV422P,
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        .v4l2_fmt = V4L2_PIX_FMT_YUV422P,
88
    },
89
    {
90
        .ff_fmt = PIX_FMT_YUYV422,
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        .v4l2_fmt = V4L2_PIX_FMT_YUYV,
92
    },
93
    {
94
        .ff_fmt = PIX_FMT_UYVY422,
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        .v4l2_fmt = V4L2_PIX_FMT_UYVY,
96
    },
97
    {
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        .ff_fmt = PIX_FMT_YUV411P,
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        .v4l2_fmt = V4L2_PIX_FMT_YUV411P,
100
    },
101
    {
102
        .ff_fmt = PIX_FMT_YUV410P,
103
        .v4l2_fmt = V4L2_PIX_FMT_YUV410,
104
    },
105
    {
106
        .ff_fmt = PIX_FMT_RGB555,
107
        .v4l2_fmt = V4L2_PIX_FMT_RGB555,
108
    },
109
    {
110
        .ff_fmt = PIX_FMT_RGB565,
111
        .v4l2_fmt = V4L2_PIX_FMT_RGB565,
112
    },
113
    {
114
        .ff_fmt = PIX_FMT_BGR24,
115
        .v4l2_fmt = V4L2_PIX_FMT_BGR24,
116
    },
117
    {
118
        .ff_fmt = PIX_FMT_RGB24,
119
        .v4l2_fmt = V4L2_PIX_FMT_RGB24,
120
    },
121
    {
122
        .ff_fmt = PIX_FMT_BGRA,
123
        .v4l2_fmt = V4L2_PIX_FMT_BGR32,
124
    },
125
    {
126
        .ff_fmt = PIX_FMT_GRAY8,
127
        .v4l2_fmt = V4L2_PIX_FMT_GREY,
128
    },
129
};
130

    
131
static int device_open(AVFormatContext *ctx, uint32_t *capabilities)
132
{
133
    struct v4l2_capability cap;
134
    int fd;
135
    int res;
136
    int flags = O_RDWR;
137

    
138
    if (ctx->flags & AVFMT_FLAG_NONBLOCK) {
139
        flags |= O_NONBLOCK;
140
    }
141
    fd = open(ctx->filename, flags, 0);
142
    if (fd < 0) {
143
        av_log(ctx, AV_LOG_ERROR, "Cannot open video device %s : %s\n",
144
                 ctx->filename, strerror(errno));
145

    
146
        return -1;
147
    }
148

    
149
    res = ioctl(fd, VIDIOC_QUERYCAP, &cap);
150
    // ENOIOCTLCMD definition only availble on __KERNEL__
151
    if (res < 0 && errno == 515)
152
    {
153
        av_log(ctx, AV_LOG_ERROR, "QUERYCAP not implemented, probably V4L device but not supporting V4L2\n");
154
        close(fd);
155

    
156
        return -1;
157
    }
158
    if (res < 0) {
159
        av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_QUERYCAP): %s\n",
160
                 strerror(errno));
161
        close(fd);
162

    
163
        return -1;
164
    }
165
    if ((cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) == 0) {
166
        av_log(ctx, AV_LOG_ERROR, "Not a video capture device\n");
167
        close(fd);
168

    
169
        return -1;
170
    }
171
    *capabilities = cap.capabilities;
172

    
173
    return fd;
174
}
175

    
176
static int device_init(AVFormatContext *ctx, int *width, int *height, int pix_fmt)
177
{
178
    struct video_data *s = ctx->priv_data;
179
    int fd = s->fd;
180
    struct v4l2_format fmt;
181
    int res;
182

    
183
    memset(&fmt, 0, sizeof(struct v4l2_format));
184
    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
185
    fmt.fmt.pix.width = *width;
186
    fmt.fmt.pix.height = *height;
187
    fmt.fmt.pix.pixelformat = pix_fmt;
188
    fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
189
    res = ioctl(fd, VIDIOC_S_FMT, &fmt);
190
    if ((*width != fmt.fmt.pix.width) || (*height != fmt.fmt.pix.height)) {
191
        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);
192
        *width = fmt.fmt.pix.width;
193
        *height = fmt.fmt.pix.height;
194
    }
195

    
196
    if (pix_fmt != fmt.fmt.pix.pixelformat) {
197
        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);
198
        res = -1;
199
    }
200

    
201
    return res;
202
}
203

    
204
static int first_field(int fd)
205
{
206
    int res;
207
    v4l2_std_id std;
208

    
209
    res = ioctl(fd, VIDIOC_G_STD, &std);
210
    if (res < 0) {
211
        return 0;
212
    }
213
    if (std & V4L2_STD_NTSC) {
214
        return 0;
215
    }
216

    
217
    return 1;
218
}
219

    
220
static uint32_t fmt_ff2v4l(enum PixelFormat pix_fmt)
221
{
222
    int i;
223

    
224
    for (i = 0; i < FF_ARRAY_ELEMS(fmt_conversion_table); i++) {
225
        if (fmt_conversion_table[i].ff_fmt == pix_fmt) {
226
            return fmt_conversion_table[i].v4l2_fmt;
227
        }
228
    }
229

    
230
    return 0;
231
}
232

    
233
static enum PixelFormat fmt_v4l2ff(uint32_t pix_fmt)
234
{
235
    int i;
236

    
237
    for (i = 0; i < FF_ARRAY_ELEMS(fmt_conversion_table); i++) {
238
        if (fmt_conversion_table[i].v4l2_fmt == pix_fmt) {
239
            return fmt_conversion_table[i].ff_fmt;
240
        }
241
    }
242

    
243
    return PIX_FMT_NONE;
244
}
245

    
246
static int mmap_init(AVFormatContext *ctx)
247
{
248
    struct video_data *s = ctx->priv_data;
249
    struct v4l2_requestbuffers req;
250
    int i, res;
251

    
252
    memset(&req, 0, sizeof(struct v4l2_requestbuffers));
253
    req.count = desired_video_buffers;
254
    req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
255
    req.memory = V4L2_MEMORY_MMAP;
256
    res = ioctl (s->fd, VIDIOC_REQBUFS, &req);
257
    if (res < 0) {
258
        if (errno == EINVAL) {
259
            av_log(ctx, AV_LOG_ERROR, "Device does not support mmap\n");
260
        } else {
261
            av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_REQBUFS)\n");
262
        }
263

    
264
        return -1;
265
    }
266

    
267
    if (req.count < 2) {
268
        av_log(ctx, AV_LOG_ERROR, "Insufficient buffer memory\n");
269

    
270
        return -1;
271
    }
272
    s->buffers = req.count;
273
    s->buf_start = av_malloc(sizeof(void *) * s->buffers);
274
    if (s->buf_start == NULL) {
275
        av_log(ctx, AV_LOG_ERROR, "Cannot allocate buffer pointers\n");
276

    
277
        return -1;
278
    }
279
    s->buf_len = av_malloc(sizeof(unsigned int) * s->buffers);
280
    if (s->buf_len == NULL) {
281
        av_log(ctx, AV_LOG_ERROR, "Cannot allocate buffer sizes\n");
282
        av_free(s->buf_start);
283

    
284
        return -1;
285
    }
286

    
287
    for (i = 0; i < req.count; i++) {
288
        struct v4l2_buffer buf;
289

    
290
        memset(&buf, 0, sizeof(struct v4l2_buffer));
291
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
292
        buf.memory = V4L2_MEMORY_MMAP;
293
        buf.index = i;
294
        res = ioctl (s->fd, VIDIOC_QUERYBUF, &buf);
295
        if (res < 0) {
296
            av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_QUERYBUF)\n");
297

    
298
            return -1;
299
        }
300

    
301
        s->buf_len[i] = buf.length;
302
        if (s->buf_len[i] < s->frame_size) {
303
            av_log(ctx, AV_LOG_ERROR, "Buffer len [%d] = %d != %d\n", i, s->buf_len[i], s->frame_size);
304

    
305
            return -1;
306
        }
307
        s->buf_start[i] = mmap (NULL, buf.length,
308
                        PROT_READ | PROT_WRITE, MAP_SHARED, s->fd, buf.m.offset);
309
        if (s->buf_start[i] == MAP_FAILED) {
310
            av_log(ctx, AV_LOG_ERROR, "mmap: %s\n", strerror(errno));
311

    
312
            return -1;
313
        }
314
    }
315

    
316
    return 0;
317
}
318

    
319
static int read_init(AVFormatContext *ctx)
320
{
321
    return -1;
322
}
323

    
324
static void mmap_release_buffer(AVPacket *pkt)
325
{
326
    struct v4l2_buffer buf;
327
    int res, fd;
328
    struct buff_data *buf_descriptor = pkt->priv;
329

    
330
    memset(&buf, 0, sizeof(struct v4l2_buffer));
331
    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
332
    buf.memory = V4L2_MEMORY_MMAP;
333
    buf.index = buf_descriptor->index;
334
    fd = buf_descriptor->fd;
335
    av_free(buf_descriptor);
336

    
337
    res = ioctl (fd, VIDIOC_QBUF, &buf);
338
    if (res < 0) {
339
        av_log(NULL, AV_LOG_ERROR, "ioctl(VIDIOC_QBUF)\n");
340
    }
341
    pkt->data = NULL;
342
    pkt->size = 0;
343
}
344

    
345
static int mmap_read_frame(AVFormatContext *ctx, AVPacket *pkt)
346
{
347
    struct video_data *s = ctx->priv_data;
348
    struct v4l2_buffer buf;
349
    struct buff_data *buf_descriptor;
350
    int res;
351

    
352
    memset(&buf, 0, sizeof(struct v4l2_buffer));
353
    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
354
    buf.memory = V4L2_MEMORY_MMAP;
355

    
356
    /* FIXME: Some special treatment might be needed in case of loss of signal... */
357
    while ((res = ioctl(s->fd, VIDIOC_DQBUF, &buf)) < 0 && (errno == EINTR));
358
    if (res < 0) {
359
        if (errno == EAGAIN) {
360
            pkt->size = 0;
361

    
362
            return AVERROR(EAGAIN);
363
        }
364
        av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_DQBUF): %s\n", strerror(errno));
365

    
366
        return -1;
367
    }
368
    assert (buf.index < s->buffers);
369
    if (buf.bytesused != s->frame_size) {
370
        av_log(ctx, AV_LOG_ERROR, "The v4l2 frame is %d bytes, but %d bytes are expected\n", buf.bytesused, s->frame_size);
371

    
372
        return -1;
373
    }
374

    
375
    /* Image is at s->buff_start[buf.index] */
376
    pkt->data= s->buf_start[buf.index];
377
    pkt->size = buf.bytesused;
378
    pkt->pts = buf.timestamp.tv_sec * INT64_C(1000000) + buf.timestamp.tv_usec;
379
    pkt->destruct = mmap_release_buffer;
380
    buf_descriptor = av_malloc(sizeof(struct buff_data));
381
    if (buf_descriptor == NULL) {
382
        /* Something went wrong... Since av_malloc() failed, we cannot even
383
         * allocate a buffer for memcopying into it
384
         */
385
        av_log(ctx, AV_LOG_ERROR, "Failed to allocate a buffer descriptor\n");
386
        res = ioctl (s->fd, VIDIOC_QBUF, &buf);
387

    
388
        return -1;
389
    }
390
    buf_descriptor->fd = s->fd;
391
    buf_descriptor->index = buf.index;
392
    pkt->priv = buf_descriptor;
393

    
394
    return s->buf_len[buf.index];
395
}
396

    
397
static int read_frame(AVFormatContext *ctx, AVPacket *pkt)
398
{
399
    return -1;
400
}
401

    
402
static int mmap_start(AVFormatContext *ctx)
403
{
404
    struct video_data *s = ctx->priv_data;
405
    enum v4l2_buf_type type;
406
    int i, res;
407

    
408
    for (i = 0; i < s->buffers; i++) {
409
        struct v4l2_buffer buf;
410

    
411
        memset(&buf, 0, sizeof(struct v4l2_buffer));
412
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
413
        buf.memory = V4L2_MEMORY_MMAP;
414
        buf.index  = i;
415

    
416
        res = ioctl (s->fd, VIDIOC_QBUF, &buf);
417
        if (res < 0) {
418
            av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_QBUF): %s\n", strerror(errno));
419

    
420
            return -1;
421
        }
422
    }
423

    
424
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
425
    res = ioctl (s->fd, VIDIOC_STREAMON, &type);
426
    if (res < 0) {
427
        av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_STREAMON): %s\n", strerror(errno));
428

    
429
        return -1;
430
    }
431

    
432
    return 0;
433
}
434

    
435
static void mmap_close(struct video_data *s)
436
{
437
    enum v4l2_buf_type type;
438
    int i;
439

    
440
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
441
    /* We do not check for the result, because we could
442
     * not do anything about it anyway...
443
     */
444
    ioctl(s->fd, VIDIOC_STREAMOFF, &type);
445
    for (i = 0; i < s->buffers; i++) {
446
        munmap(s->buf_start[i], s->buf_len[i]);
447
    }
448
    av_free(s->buf_start);
449
    av_free(s->buf_len);
450
}
451

    
452
static int v4l2_set_parameters( AVFormatContext *s1, AVFormatParameters *ap )
453
{
454
    struct video_data *s = s1->priv_data;
455
    struct v4l2_input input;
456
    struct v4l2_standard standard;
457
    int i;
458

    
459
    if(ap->channel>=0) {
460
        /* set tv video input */
461
        memset (&input, 0, sizeof (input));
462
        input.index = ap->channel;
463
        if(ioctl (s->fd, VIDIOC_ENUMINPUT, &input) < 0) {
464
            av_log(s1, AV_LOG_ERROR, "The V4L2 driver ioctl enum input failed:\n");
465
            return AVERROR(EIO);
466
        }
467

    
468
        av_log(s1, AV_LOG_DEBUG, "The V4L2 driver set input_id: %d, input: %s\n",
469
               ap->channel, input.name);
470
        if(ioctl (s->fd, VIDIOC_S_INPUT, &input.index) < 0 ) {
471
            av_log(s1, AV_LOG_ERROR, "The V4L2 driver ioctl set input(%d) failed\n",
472
                   ap->channel);
473
            return AVERROR(EIO);
474
        }
475
    }
476

    
477
    if(ap->standard) {
478
        av_log(s1, AV_LOG_DEBUG, "The V4L2 driver set standard: %s\n",
479
               ap->standard );
480
        /* set tv standard */
481
        memset (&standard, 0, sizeof (standard));
482
        for(i=0;;i++) {
483
            standard.index = i;
484
            if (ioctl(s->fd, VIDIOC_ENUMSTD, &standard) < 0) {
485
                av_log(s1, AV_LOG_ERROR, "The V4L2 driver ioctl set standard(%s) failed\n",
486
                       ap->standard);
487
                return AVERROR(EIO);
488
            }
489

    
490
            if(!strcasecmp(standard.name, ap->standard)) {
491
                break;
492
            }
493
        }
494

    
495
        av_log(s1, AV_LOG_DEBUG, "The V4L2 driver set standard: %s, id: %"PRIu64"\n",
496
               ap->standard, standard.id);
497
        if (ioctl(s->fd, VIDIOC_S_STD, &standard.id) < 0) {
498
            av_log(s1, AV_LOG_ERROR, "The V4L2 driver ioctl set standard(%s) failed\n",
499
                   ap->standard);
500
            return AVERROR(EIO);
501
        }
502
    }
503

    
504
    return 0;
505
}
506

    
507
static int v4l2_read_header(AVFormatContext *s1, AVFormatParameters *ap)
508
{
509
    struct video_data *s = s1->priv_data;
510
    AVStream *st;
511
    int width, height;
512
    int res, frame_rate, frame_rate_base;
513
    uint32_t desired_format, capabilities;
514

    
515
    if (ap->width <= 0 || ap->height <= 0) {
516
        av_log(s1, AV_LOG_ERROR, "Wrong size (%dx%d)\n", ap->width, ap->height);
517
        return -1;
518
    }
519
    if (ap->time_base.den <= 0) {
520
        av_log(s1, AV_LOG_ERROR, "Wrong time base (%d)\n", ap->time_base.den);
521
        return -1;
522
    }
523

    
524
    width = ap->width;
525
    height = ap->height;
526
    frame_rate = ap->time_base.den;
527
    frame_rate_base = ap->time_base.num;
528

    
529
    if(avcodec_check_dimensions(s1, ap->width, ap->height) < 0)
530
        return -1;
531

    
532
    st = av_new_stream(s1, 0);
533
    if (!st) {
534
        return AVERROR(ENOMEM);
535
    }
536
    av_set_pts_info(st, 64, 1, 1000000); /* 64 bits pts in us */
537

    
538
    s->width = width;
539
    s->height = height;
540
    s->frame_rate      = frame_rate;
541
    s->frame_rate_base = frame_rate_base;
542

    
543
    capabilities = 0;
544
    s->fd = device_open(s1, &capabilities);
545
    if (s->fd < 0) {
546
        return AVERROR(EIO);
547
    }
548
    av_log(s1, AV_LOG_INFO, "[%d]Capabilities: %x\n", s->fd, capabilities);
549

    
550
    desired_format = fmt_ff2v4l(ap->pix_fmt);
551
    if (desired_format == 0 || (device_init(s1, &width, &height, desired_format) < 0)) {
552
        int i, done;
553

    
554
        done = 0; i = 0;
555
        while (!done) {
556
            desired_format = fmt_conversion_table[i].v4l2_fmt;
557
            if (device_init(s1, &width, &height, desired_format) < 0) {
558
                desired_format = 0;
559
                i++;
560
            } else {
561
               done = 1;
562
            }
563
            if (i == FF_ARRAY_ELEMS(fmt_conversion_table)) {
564
               done = 1;
565
            }
566
        }
567
    }
568
    if (desired_format == 0) {
569
        av_log(s1, AV_LOG_ERROR, "Cannot find a proper format.\n");
570
        close(s->fd);
571

    
572
        return AVERROR(EIO);
573
    }
574
    s->frame_format = desired_format;
575

    
576
    if( v4l2_set_parameters( s1, ap ) < 0 )
577
        return AVERROR(EIO);
578

    
579
    st->codec->pix_fmt = fmt_v4l2ff(desired_format);
580
    s->frame_size = avpicture_get_size(st->codec->pix_fmt, width, height);
581
    if (capabilities & V4L2_CAP_STREAMING) {
582
        s->io_method = io_mmap;
583
        res = mmap_init(s1);
584
        if (res == 0) {
585
            res = mmap_start(s1);
586
        }
587
    } else {
588
        s->io_method = io_read;
589
        res = read_init(s1);
590
    }
591
    if (res < 0) {
592
        close(s->fd);
593

    
594
        return AVERROR(EIO);
595
    }
596
    s->top_field_first = first_field(s->fd);
597

    
598
    st->codec->codec_type = CODEC_TYPE_VIDEO;
599
    st->codec->codec_id = CODEC_ID_RAWVIDEO;
600
    st->codec->width = width;
601
    st->codec->height = height;
602
    st->codec->time_base.den = frame_rate;
603
    st->codec->time_base.num = frame_rate_base;
604
    st->codec->bit_rate = s->frame_size * 1/av_q2d(st->codec->time_base) * 8;
605

    
606
    return 0;
607
}
608

    
609
static int v4l2_read_packet(AVFormatContext *s1, AVPacket *pkt)
610
{
611
    struct video_data *s = s1->priv_data;
612
    int res;
613

    
614
    if (s->io_method == io_mmap) {
615
        av_init_packet(pkt);
616
        res = mmap_read_frame(s1, pkt);
617
    } else if (s->io_method == io_read) {
618
        if (av_new_packet(pkt, s->frame_size) < 0)
619
            return AVERROR(EIO);
620

    
621
        res = read_frame(s1, pkt);
622
    } else {
623
        return AVERROR(EIO);
624
    }
625
    if (res < 0) {
626
        return res;
627
    }
628

    
629
    if (s1->streams[0]->codec->coded_frame) {
630
        s1->streams[0]->codec->coded_frame->interlaced_frame = 1;
631
        s1->streams[0]->codec->coded_frame->top_field_first = s->top_field_first;
632
    }
633

    
634
    return s->frame_size;
635
}
636

    
637
static int v4l2_read_close(AVFormatContext *s1)
638
{
639
    struct video_data *s = s1->priv_data;
640

    
641
    if (s->io_method == io_mmap) {
642
        mmap_close(s);
643
    }
644

    
645
    close(s->fd);
646
    return 0;
647
}
648

    
649
AVInputFormat v4l2_demuxer = {
650
    "video4linux2",
651
    NULL_IF_CONFIG_SMALL("Video4Linux2 device grab"),
652
    sizeof(struct video_data),
653
    NULL,
654
    v4l2_read_header,
655
    v4l2_read_packet,
656
    v4l2_read_close,
657
    .flags = AVFMT_NOFILE,
658
};