libavdevice/v4l2.c

   1 /*
   2  * Video4Linux2 grab interface
   3  * Copyright (c) 2000,2001 Fabrice Bellard
   4  * Copyright (c) 2006 Luca Abeni
   5  *
   6  * Part of this file is based on the V4L2 video capture example
   7  * (http://v4l2spec.bytesex.org/v4l2spec/capture.c)
   8  *
   9  * Thanks to Michael Niedermayer for providing the mapping between
  10  * V4L2_PIX_FMT_* and PIX_FMT_*
  11  *
  12  *
  13  * This file is part of FFmpeg.
  14  *
  15  * FFmpeg 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.
  19  *
  20  * FFmpeg 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.
  24  *
  25  * You should have received a copy of the GNU Lesser General Public
  26  * License along with FFmpeg; if not, write to the Free Software
  27  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  28  */
  29
  30 #undef __STRICT_ANSI__ //workaround due to broken kernel headers
  31 #include "config.h"
  32 #include "libavformat/avformat.h"
  33 #include <unistd.h>
  34 #include <fcntl.h>
  35 #include <sys/ioctl.h>
  36 #include <sys/mman.h>
  37 #include <sys/time.h>
  38 #if HAVE_SYS_VIDEOIO_H
  39 #include <sys/videoio.h>
  40 #else
  41 #include <asm/types.h>
  42 #include <linux/videodev2.h>
  43 #endif
  44 #include <time.h>
  45 #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;
  57     int frame_format; /* V4L2_PIX_FMT_* */
  58     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;
  65     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;
  75     enum CodecID codec_id;
  76     uint32_t v4l2_fmt;
  77 };
  78
  79 static struct fmt_map fmt_conversion_table[] = {
  80     {
  81         .ff_fmt = PIX_FMT_YUV420P,
  82         .codec_id = CODEC_ID_RAWVIDEO,
  83         .v4l2_fmt = V4L2_PIX_FMT_YUV420,
  84     },
  85     {
  86         .ff_fmt = PIX_FMT_YUV422P,
  87         .codec_id = CODEC_ID_RAWVIDEO,
  88         .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,
 107         .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,
 128         .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, ap->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 (ap->video_codec_id == CODEC_ID_NONE ||
 564                 fmt_conversion_table[i].codec_id == ap->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", ap->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 = CODEC_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 };