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ffmpeg / libavdevice / v4l2.c @ 72415b2a

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1
/*
2
 * Video4Linux2 grab interface
3
 * Copyright (c) 2000,2001 Fabrice Bellard
4
 * 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
16
 * 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,
21
 * 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
28
 */
29

    
30
#undef __STRICT_ANSI__ //workaround due to broken kernel headers
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#include "config.h"
32
#include "libavformat/avformat.h"
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#include <unistd.h>
34
#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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#if HAVE_SYS_VIDEOIO_H
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#include <sys/videoio.h>
40
#else
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#include <asm/types.h>
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#include <linux/videodev2.h>
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#endif
44
#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_size;
61
    int top_field_first;
62

    
63
    int buffers;
64
    void **buf_start;
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    unsigned int *buf_len;
66
};
67

    
68
struct buff_data {
69
    int index;
70
    int fd;
71
};
72

    
73
struct fmt_map {
74
    enum PixelFormat ff_fmt;
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    enum CodecID codec_id;
76
    uint32_t v4l2_fmt;
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};
78

    
79
static struct fmt_map fmt_conversion_table[] = {
80
    {
81
        .ff_fmt = PIX_FMT_YUV420P,
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        .codec_id = CODEC_ID_RAWVIDEO,
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        .v4l2_fmt = V4L2_PIX_FMT_YUV420,
84
    },
85
    {
86
        .ff_fmt = PIX_FMT_YUV422P,
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        .codec_id = CODEC_ID_RAWVIDEO,
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        .v4l2_fmt = V4L2_PIX_FMT_YUV422P,
89
    },
90
    {
91
        .ff_fmt = PIX_FMT_YUYV422,
92
        .codec_id = CODEC_ID_RAWVIDEO,
93
        .v4l2_fmt = V4L2_PIX_FMT_YUYV,
94
    },
95
    {
96
        .ff_fmt = PIX_FMT_UYVY422,
97
        .codec_id = CODEC_ID_RAWVIDEO,
98
        .v4l2_fmt = V4L2_PIX_FMT_UYVY,
99
    },
100
    {
101
        .ff_fmt = PIX_FMT_YUV411P,
102
        .codec_id = CODEC_ID_RAWVIDEO,
103
        .v4l2_fmt = V4L2_PIX_FMT_YUV411P,
104
    },
105
    {
106
        .ff_fmt = PIX_FMT_YUV410P,
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        .codec_id = CODEC_ID_RAWVIDEO,
108
        .v4l2_fmt = V4L2_PIX_FMT_YUV410,
109
    },
110
    {
111
        .ff_fmt = PIX_FMT_RGB555,
112
        .codec_id = CODEC_ID_RAWVIDEO,
113
        .v4l2_fmt = V4L2_PIX_FMT_RGB555,
114
    },
115
    {
116
        .ff_fmt = PIX_FMT_RGB565,
117
        .codec_id = CODEC_ID_RAWVIDEO,
118
        .v4l2_fmt = V4L2_PIX_FMT_RGB565,
119
    },
120
    {
121
        .ff_fmt = PIX_FMT_BGR24,
122
        .codec_id = CODEC_ID_RAWVIDEO,
123
        .v4l2_fmt = V4L2_PIX_FMT_BGR24,
124
    },
125
    {
126
        .ff_fmt = PIX_FMT_RGB24,
127
        .codec_id = CODEC_ID_RAWVIDEO,
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        .v4l2_fmt = V4L2_PIX_FMT_RGB24,
129
    },
130
    {
131
        .ff_fmt = PIX_FMT_BGRA,
132
        .codec_id = CODEC_ID_RAWVIDEO,
133
        .v4l2_fmt = V4L2_PIX_FMT_BGR32,
134
    },
135
    {
136
        .ff_fmt = PIX_FMT_GRAY8,
137
        .codec_id = CODEC_ID_RAWVIDEO,
138
        .v4l2_fmt = V4L2_PIX_FMT_GREY,
139
    },
140
    {
141
        .ff_fmt = PIX_FMT_NONE,
142
        .codec_id = CODEC_ID_MJPEG,
143
        .v4l2_fmt = V4L2_PIX_FMT_MJPEG,
144
    },
145
    {
146
        .ff_fmt = PIX_FMT_NONE,
147
        .codec_id = CODEC_ID_MJPEG,
148
        .v4l2_fmt = V4L2_PIX_FMT_JPEG,
149
    },
150
};
151

    
152
static int device_open(AVFormatContext *ctx, uint32_t *capabilities)
153
{
154
    struct v4l2_capability cap;
155
    int fd;
156
    int res;
157
    int flags = O_RDWR;
158

    
159
    if (ctx->flags & AVFMT_FLAG_NONBLOCK) {
160
        flags |= O_NONBLOCK;
161
    }
162
    fd = open(ctx->filename, flags, 0);
163
    if (fd < 0) {
164
        av_log(ctx, AV_LOG_ERROR, "Cannot open video device %s : %s\n",
165
                 ctx->filename, strerror(errno));
166

    
167
        return -1;
168
    }
169

    
170
    res = ioctl(fd, VIDIOC_QUERYCAP, &cap);
171
    // ENOIOCTLCMD definition only availble on __KERNEL__
172
    if (res < 0 && errno == 515)
173
    {
174
        av_log(ctx, AV_LOG_ERROR, "QUERYCAP not implemented, probably V4L device but not supporting V4L2\n");
175
        close(fd);
176

    
177
        return -1;
178
    }
179
    if (res < 0) {
180
        av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_QUERYCAP): %s\n",
181
                 strerror(errno));
182
        close(fd);
183

    
184
        return -1;
185
    }
186
    if ((cap.capabilities & V4L2_CAP_VIDEO_CAPTURE) == 0) {
187
        av_log(ctx, AV_LOG_ERROR, "Not a video capture device\n");
188
        close(fd);
189

    
190
        return -1;
191
    }
192
    *capabilities = cap.capabilities;
193

    
194
    return fd;
195
}
196

    
197
static int device_init(AVFormatContext *ctx, int *width, int *height, uint32_t pix_fmt)
198
{
199
    struct video_data *s = ctx->priv_data;
200
    int fd = s->fd;
201
    struct v4l2_format fmt;
202
    int res;
203

    
204
    memset(&fmt, 0, sizeof(struct v4l2_format));
205
    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
206
    fmt.fmt.pix.width = *width;
207
    fmt.fmt.pix.height = *height;
208
    fmt.fmt.pix.pixelformat = pix_fmt;
209
    fmt.fmt.pix.field = V4L2_FIELD_INTERLACED;
210
    res = ioctl(fd, VIDIOC_S_FMT, &fmt);
211
    if ((*width != fmt.fmt.pix.width) || (*height != fmt.fmt.pix.height)) {
212
        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);
213
        *width = fmt.fmt.pix.width;
214
        *height = fmt.fmt.pix.height;
215
    }
216

    
217
    if (pix_fmt != fmt.fmt.pix.pixelformat) {
218
        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);
219
        res = -1;
220
    }
221

    
222
    return res;
223
}
224

    
225
static int first_field(int fd)
226
{
227
    int res;
228
    v4l2_std_id std;
229

    
230
    res = ioctl(fd, VIDIOC_G_STD, &std);
231
    if (res < 0) {
232
        return 0;
233
    }
234
    if (std & V4L2_STD_NTSC) {
235
        return 0;
236
    }
237

    
238
    return 1;
239
}
240

    
241
static uint32_t fmt_ff2v4l(enum PixelFormat pix_fmt, enum CodecID codec_id)
242
{
243
    int i;
244

    
245
    for (i = 0; i < FF_ARRAY_ELEMS(fmt_conversion_table); i++) {
246
        if ((codec_id == CODEC_ID_NONE ||
247
             fmt_conversion_table[i].codec_id == codec_id) &&
248
            (pix_fmt == PIX_FMT_NONE ||
249
             fmt_conversion_table[i].ff_fmt == pix_fmt)) {
250
            return fmt_conversion_table[i].v4l2_fmt;
251
        }
252
    }
253

    
254
    return 0;
255
}
256

    
257
static enum PixelFormat fmt_v4l2ff(uint32_t v4l2_fmt, enum CodecID codec_id)
258
{
259
    int i;
260

    
261
    for (i = 0; i < FF_ARRAY_ELEMS(fmt_conversion_table); i++) {
262
        if (fmt_conversion_table[i].v4l2_fmt == v4l2_fmt &&
263
            fmt_conversion_table[i].codec_id == codec_id) {
264
            return fmt_conversion_table[i].ff_fmt;
265
        }
266
    }
267

    
268
    return PIX_FMT_NONE;
269
}
270

    
271
static enum CodecID fmt_v4l2codec(uint32_t v4l2_fmt)
272
{
273
    int i;
274

    
275
    for (i = 0; i < FF_ARRAY_ELEMS(fmt_conversion_table); i++) {
276
        if (fmt_conversion_table[i].v4l2_fmt == v4l2_fmt) {
277
            return fmt_conversion_table[i].codec_id;
278
        }
279
    }
280

    
281
    return CODEC_ID_NONE;
282
}
283

    
284
static int mmap_init(AVFormatContext *ctx)
285
{
286
    struct video_data *s = ctx->priv_data;
287
    struct v4l2_requestbuffers req;
288
    int i, res;
289

    
290
    memset(&req, 0, sizeof(struct v4l2_requestbuffers));
291
    req.count = desired_video_buffers;
292
    req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
293
    req.memory = V4L2_MEMORY_MMAP;
294
    res = ioctl (s->fd, VIDIOC_REQBUFS, &req);
295
    if (res < 0) {
296
        if (errno == EINVAL) {
297
            av_log(ctx, AV_LOG_ERROR, "Device does not support mmap\n");
298
        } else {
299
            av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_REQBUFS)\n");
300
        }
301

    
302
        return -1;
303
    }
304

    
305
    if (req.count < 2) {
306
        av_log(ctx, AV_LOG_ERROR, "Insufficient buffer memory\n");
307

    
308
        return -1;
309
    }
310
    s->buffers = req.count;
311
    s->buf_start = av_malloc(sizeof(void *) * s->buffers);
312
    if (s->buf_start == NULL) {
313
        av_log(ctx, AV_LOG_ERROR, "Cannot allocate buffer pointers\n");
314

    
315
        return -1;
316
    }
317
    s->buf_len = av_malloc(sizeof(unsigned int) * s->buffers);
318
    if (s->buf_len == NULL) {
319
        av_log(ctx, AV_LOG_ERROR, "Cannot allocate buffer sizes\n");
320
        av_free(s->buf_start);
321

    
322
        return -1;
323
    }
324

    
325
    for (i = 0; i < req.count; i++) {
326
        struct v4l2_buffer buf;
327

    
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 = i;
332
        res = ioctl (s->fd, VIDIOC_QUERYBUF, &buf);
333
        if (res < 0) {
334
            av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_QUERYBUF)\n");
335

    
336
            return -1;
337
        }
338

    
339
        s->buf_len[i] = buf.length;
340
        if (s->frame_size > 0 && s->buf_len[i] < s->frame_size) {
341
            av_log(ctx, AV_LOG_ERROR, "Buffer len [%d] = %d != %d\n", i, s->buf_len[i], s->frame_size);
342

    
343
            return -1;
344
        }
345
        s->buf_start[i] = mmap (NULL, buf.length,
346
                        PROT_READ | PROT_WRITE, MAP_SHARED, s->fd, buf.m.offset);
347
        if (s->buf_start[i] == MAP_FAILED) {
348
            av_log(ctx, AV_LOG_ERROR, "mmap: %s\n", strerror(errno));
349

    
350
            return -1;
351
        }
352
    }
353

    
354
    return 0;
355
}
356

    
357
static int read_init(AVFormatContext *ctx)
358
{
359
    return -1;
360
}
361

    
362
static void mmap_release_buffer(AVPacket *pkt)
363
{
364
    struct v4l2_buffer buf;
365
    int res, fd;
366
    struct buff_data *buf_descriptor = pkt->priv;
367

    
368
    if (pkt->data == NULL) {
369
         return;
370
    }
371

    
372
    memset(&buf, 0, sizeof(struct v4l2_buffer));
373
    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
374
    buf.memory = V4L2_MEMORY_MMAP;
375
    buf.index = buf_descriptor->index;
376
    fd = buf_descriptor->fd;
377
    av_free(buf_descriptor);
378

    
379
    res = ioctl (fd, VIDIOC_QBUF, &buf);
380
    if (res < 0) {
381
        av_log(NULL, AV_LOG_ERROR, "ioctl(VIDIOC_QBUF)\n");
382
    }
383
    pkt->data = NULL;
384
    pkt->size = 0;
385
}
386

    
387
static int mmap_read_frame(AVFormatContext *ctx, AVPacket *pkt)
388
{
389
    struct video_data *s = ctx->priv_data;
390
    struct v4l2_buffer buf;
391
    struct buff_data *buf_descriptor;
392
    int res;
393

    
394
    memset(&buf, 0, sizeof(struct v4l2_buffer));
395
    buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
396
    buf.memory = V4L2_MEMORY_MMAP;
397

    
398
    /* FIXME: Some special treatment might be needed in case of loss of signal... */
399
    while ((res = ioctl(s->fd, VIDIOC_DQBUF, &buf)) < 0 && (errno == EINTR));
400
    if (res < 0) {
401
        if (errno == EAGAIN) {
402
            pkt->size = 0;
403

    
404
            return AVERROR(EAGAIN);
405
        }
406
        av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_DQBUF): %s\n", strerror(errno));
407

    
408
        return -1;
409
    }
410
    assert (buf.index < s->buffers);
411
    if (s->frame_size > 0 && buf.bytesused != s->frame_size) {
412
        av_log(ctx, AV_LOG_ERROR, "The v4l2 frame is %d bytes, but %d bytes are expected\n", buf.bytesused, s->frame_size);
413

    
414
        return -1;
415
    }
416

    
417
    /* Image is at s->buff_start[buf.index] */
418
    pkt->data= s->buf_start[buf.index];
419
    pkt->size = buf.bytesused;
420
    pkt->pts = buf.timestamp.tv_sec * INT64_C(1000000) + buf.timestamp.tv_usec;
421
    pkt->destruct = mmap_release_buffer;
422
    buf_descriptor = av_malloc(sizeof(struct buff_data));
423
    if (buf_descriptor == NULL) {
424
        /* Something went wrong... Since av_malloc() failed, we cannot even
425
         * allocate a buffer for memcopying into it
426
         */
427
        av_log(ctx, AV_LOG_ERROR, "Failed to allocate a buffer descriptor\n");
428
        res = ioctl (s->fd, VIDIOC_QBUF, &buf);
429

    
430
        return -1;
431
    }
432
    buf_descriptor->fd = s->fd;
433
    buf_descriptor->index = buf.index;
434
    pkt->priv = buf_descriptor;
435

    
436
    return s->buf_len[buf.index];
437
}
438

    
439
static int read_frame(AVFormatContext *ctx, AVPacket *pkt)
440
{
441
    return -1;
442
}
443

    
444
static int mmap_start(AVFormatContext *ctx)
445
{
446
    struct video_data *s = ctx->priv_data;
447
    enum v4l2_buf_type type;
448
    int i, res;
449

    
450
    for (i = 0; i < s->buffers; i++) {
451
        struct v4l2_buffer buf;
452

    
453
        memset(&buf, 0, sizeof(struct v4l2_buffer));
454
        buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
455
        buf.memory = V4L2_MEMORY_MMAP;
456
        buf.index  = i;
457

    
458
        res = ioctl (s->fd, VIDIOC_QBUF, &buf);
459
        if (res < 0) {
460
            av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_QBUF): %s\n", strerror(errno));
461

    
462
            return -1;
463
        }
464
    }
465

    
466
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
467
    res = ioctl (s->fd, VIDIOC_STREAMON, &type);
468
    if (res < 0) {
469
        av_log(ctx, AV_LOG_ERROR, "ioctl(VIDIOC_STREAMON): %s\n", strerror(errno));
470

    
471
        return -1;
472
    }
473

    
474
    return 0;
475
}
476

    
477
static void mmap_close(struct video_data *s)
478
{
479
    enum v4l2_buf_type type;
480
    int i;
481

    
482
    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
483
    /* We do not check for the result, because we could
484
     * not do anything about it anyway...
485
     */
486
    ioctl(s->fd, VIDIOC_STREAMOFF, &type);
487
    for (i = 0; i < s->buffers; i++) {
488
        munmap(s->buf_start[i], s->buf_len[i]);
489
    }
490
    av_free(s->buf_start);
491
    av_free(s->buf_len);
492
}
493

    
494
static int v4l2_set_parameters( AVFormatContext *s1, AVFormatParameters *ap )
495
{
496
    struct video_data *s = s1->priv_data;
497
    struct v4l2_input input;
498
    struct v4l2_standard standard;
499
    int i;
500

    
501
    if(ap->channel>=0) {
502
        /* set tv video input */
503
        memset (&input, 0, sizeof (input));
504
        input.index = ap->channel;
505
        if(ioctl (s->fd, VIDIOC_ENUMINPUT, &input) < 0) {
506
            av_log(s1, AV_LOG_ERROR, "The V4L2 driver ioctl enum input failed:\n");
507
            return AVERROR(EIO);
508
        }
509

    
510
        av_log(s1, AV_LOG_DEBUG, "The V4L2 driver set input_id: %d, input: %s\n",
511
               ap->channel, input.name);
512
        if(ioctl (s->fd, VIDIOC_S_INPUT, &input.index) < 0 ) {
513
            av_log(s1, AV_LOG_ERROR, "The V4L2 driver ioctl set input(%d) failed\n",
514
                   ap->channel);
515
            return AVERROR(EIO);
516
        }
517
    }
518

    
519
    if(ap->standard) {
520
        av_log(s1, AV_LOG_DEBUG, "The V4L2 driver set standard: %s\n",
521
               ap->standard );
522
        /* set tv standard */
523
        memset (&standard, 0, sizeof (standard));
524
        for(i=0;;i++) {
525
            standard.index = i;
526
            if (ioctl(s->fd, VIDIOC_ENUMSTD, &standard) < 0) {
527
                av_log(s1, AV_LOG_ERROR, "The V4L2 driver ioctl set standard(%s) failed\n",
528
                       ap->standard);
529
                return AVERROR(EIO);
530
            }
531

    
532
            if(!strcasecmp(standard.name, ap->standard)) {
533
                break;
534
            }
535
        }
536

    
537
        av_log(s1, AV_LOG_DEBUG, "The V4L2 driver set standard: %s, id: %"PRIu64"\n",
538
               ap->standard, (uint64_t)standard.id);
539
        if (ioctl(s->fd, VIDIOC_S_STD, &standard.id) < 0) {
540
            av_log(s1, AV_LOG_ERROR, "The V4L2 driver ioctl set standard(%s) failed\n",
541
                   ap->standard);
542
            return AVERROR(EIO);
543
        }
544
    }
545

    
546
    return 0;
547
}
548

    
549
static uint32_t device_try_init(AVFormatContext *s1,
550
                                const AVFormatParameters *ap,
551
                                int *width,
552
                                int *height,
553
                                enum CodecID *codec_id)
554
{
555
    uint32_t desired_format = fmt_ff2v4l(ap->pix_fmt, s1->video_codec_id);
556

    
557
    if (desired_format == 0 ||
558
        device_init(s1, width, height, desired_format) < 0) {
559
        int i;
560

    
561
        desired_format = 0;
562
        for (i = 0; i<FF_ARRAY_ELEMS(fmt_conversion_table); i++) {
563
            if (s1->video_codec_id == CODEC_ID_NONE ||
564
                fmt_conversion_table[i].codec_id == s1->video_codec_id) {
565
                desired_format = fmt_conversion_table[i].v4l2_fmt;
566
                if (device_init(s1, width, height, desired_format) >= 0) {
567
                    break;
568
                }
569
                desired_format = 0;
570
            }
571
        }
572
    }
573
    if (desired_format != 0) {
574
        *codec_id = fmt_v4l2codec(desired_format);
575
        assert(*codec_id != CODEC_ID_NONE);
576
    }
577

    
578
    return desired_format;
579
}
580

    
581
static int v4l2_read_header(AVFormatContext *s1, AVFormatParameters *ap)
582
{
583
    struct video_data *s = s1->priv_data;
584
    AVStream *st;
585
    int width, height;
586
    int res;
587
    uint32_t desired_format, capabilities;
588
    enum CodecID codec_id;
589

    
590
    if (ap->width <= 0 || ap->height <= 0) {
591
        av_log(s1, AV_LOG_ERROR, "Wrong size (%dx%d)\n", ap->width, ap->height);
592
        return -1;
593
    }
594

    
595
    width = ap->width;
596
    height = ap->height;
597

    
598
    if(avcodec_check_dimensions(s1, ap->width, ap->height) < 0)
599
        return -1;
600

    
601
    st = av_new_stream(s1, 0);
602
    if (!st) {
603
        return AVERROR(ENOMEM);
604
    }
605
    av_set_pts_info(st, 64, 1, 1000000); /* 64 bits pts in us */
606

    
607
    s->width = width;
608
    s->height = height;
609

    
610
    capabilities = 0;
611
    s->fd = device_open(s1, &capabilities);
612
    if (s->fd < 0) {
613
        return AVERROR(EIO);
614
    }
615
    av_log(s1, AV_LOG_INFO, "[%d]Capabilities: %x\n", s->fd, capabilities);
616

    
617
    desired_format = device_try_init(s1, ap, &width, &height, &codec_id);
618
    if (desired_format == 0) {
619
        av_log(s1, AV_LOG_ERROR, "Cannot find a proper format for "
620
               "codec_id %d, pix_fmt %d.\n", s1->video_codec_id, ap->pix_fmt);
621
        close(s->fd);
622

    
623
        return AVERROR(EIO);
624
    }
625
    s->frame_format = desired_format;
626

    
627
    if( v4l2_set_parameters( s1, ap ) < 0 )
628
        return AVERROR(EIO);
629

    
630
    st->codec->pix_fmt = fmt_v4l2ff(desired_format, codec_id);
631
    s->frame_size = avpicture_get_size(st->codec->pix_fmt, width, height);
632
    if (capabilities & V4L2_CAP_STREAMING) {
633
        s->io_method = io_mmap;
634
        res = mmap_init(s1);
635
        if (res == 0) {
636
            res = mmap_start(s1);
637
        }
638
    } else {
639
        s->io_method = io_read;
640
        res = read_init(s1);
641
    }
642
    if (res < 0) {
643
        close(s->fd);
644

    
645
        return AVERROR(EIO);
646
    }
647
    s->top_field_first = first_field(s->fd);
648

    
649
    st->codec->codec_type = AVMEDIA_TYPE_VIDEO;
650
    st->codec->codec_id = codec_id;
651
    st->codec->width = width;
652
    st->codec->height = height;
653
    st->codec->time_base.den = ap->time_base.den;
654
    st->codec->time_base.num = ap->time_base.num;
655
    st->codec->bit_rate = s->frame_size * 1/av_q2d(st->codec->time_base) * 8;
656

    
657
    return 0;
658
}
659

    
660
static int v4l2_read_packet(AVFormatContext *s1, AVPacket *pkt)
661
{
662
    struct video_data *s = s1->priv_data;
663
    int res;
664

    
665
    if (s->io_method == io_mmap) {
666
        av_init_packet(pkt);
667
        res = mmap_read_frame(s1, pkt);
668
    } else if (s->io_method == io_read) {
669
        if (av_new_packet(pkt, s->frame_size) < 0)
670
            return AVERROR(EIO);
671

    
672
        res = read_frame(s1, pkt);
673
    } else {
674
        return AVERROR(EIO);
675
    }
676
    if (res < 0) {
677
        return res;
678
    }
679

    
680
    if (s1->streams[0]->codec->coded_frame) {
681
        s1->streams[0]->codec->coded_frame->interlaced_frame = 1;
682
        s1->streams[0]->codec->coded_frame->top_field_first = s->top_field_first;
683
    }
684

    
685
    return pkt->size;
686
}
687

    
688
static int v4l2_read_close(AVFormatContext *s1)
689
{
690
    struct video_data *s = s1->priv_data;
691

    
692
    if (s->io_method == io_mmap) {
693
        mmap_close(s);
694
    }
695

    
696
    close(s->fd);
697
    return 0;
698
}
699

    
700
AVInputFormat v4l2_demuxer = {
701
    "video4linux2",
702
    NULL_IF_CONFIG_SMALL("Video4Linux2 device grab"),
703
    sizeof(struct video_data),
704
    NULL,
705
    v4l2_read_header,
706
    v4l2_read_packet,
707
    v4l2_read_close,
708
    .flags = AVFMT_NOFILE,
709
};