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ffmpeg/libav/grab.c

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/*
* Linux video grab interface
* Copyright (c) 2000,2001 Fabrice Bellard.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "avformat.h"
#include <linux/videodev.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/time.h>
#include <time.h>
typedef struct {
int fd;
int frame_format; /* see VIDEO_PALETTE_xxx */
int use_mmap;
int width, height;
int frame_rate;
INT64 time_frame;
int frame_size;
} VideoData;
const char *v4l_device = "/dev/video";
/* XXX: move all that to the context */
static struct video_capability video_cap;
static UINT8 *video_buf;
static struct video_mbuf gb_buffers;
static struct video_mmap gb_buf;
static struct video_audio audio, audio_saved;
static int gb_frame = 0;
static int grab_read_header(AVFormatContext *s1, AVFormatParameters *ap)
{
VideoData *s = s1->priv_data;
AVStream *st;
int width, height;
int video_fd, frame_size;
int ret, frame_rate;
int desired_palette;
if (!ap || ap->width <= 0 || ap->height <= 0 || ap->frame_rate <= 0)
return -1;
width = ap->width;
height = ap->height;
frame_rate = ap->frame_rate;
st = av_new_stream(s1, 0);
if (!st)
return -ENOMEM;
s->width = width;
s->height = height;
s->frame_rate = frame_rate;
video_fd = open(v4l_device, O_RDWR);
if (video_fd < 0) {
perror(v4l_device);
goto fail;
}
if (ioctl(video_fd,VIDIOCGCAP,&video_cap) < 0) {
perror("VIDIOCGCAP");
goto fail;
}
if (!(video_cap.type & VID_TYPE_CAPTURE)) {
fprintf(stderr, "Fatal: grab device does not handle capture\n");
goto fail;
}
desired_palette = -1;
if (st->codec.pix_fmt == PIX_FMT_YUV420P) {
desired_palette = VIDEO_PALETTE_YUV420P;
} else if (st->codec.pix_fmt == PIX_FMT_YUV422) {
desired_palette = VIDEO_PALETTE_YUV422;
} else if (st->codec.pix_fmt == PIX_FMT_BGR24) {
desired_palette = VIDEO_PALETTE_RGB24;
}
/* unmute audio */
ioctl(video_fd, VIDIOCGAUDIO, &audio);
memcpy(&audio_saved, &audio, sizeof(audio));
audio.flags &= ~VIDEO_AUDIO_MUTE;
ioctl(video_fd, VIDIOCSAUDIO, &audio);
ret = ioctl(video_fd,VIDIOCGMBUF,&gb_buffers);
if (ret < 0) {
/* try to use read based access */
struct video_window win;
struct video_picture pict;
int val;
win.x = 0;
win.y = 0;
win.width = width;
win.height = height;
win.chromakey = -1;
win.flags = 0;
ioctl(video_fd, VIDIOCSWIN, &win);
ioctl(video_fd, VIDIOCGPICT, &pict);
#if 0
printf("v4l: colour=%d hue=%d brightness=%d constrast=%d whiteness=%d\n",
pict.colour,
pict.hue,
pict.brightness,
pict.contrast,
pict.whiteness);
#endif
/* try to choose a suitable video format */
pict.palette = desired_palette;
if (desired_palette == -1 || (ret = ioctl(video_fd, VIDIOCSPICT, &pict)) < 0) {
pict.palette=VIDEO_PALETTE_YUV420P;
ret = ioctl(video_fd, VIDIOCSPICT, &pict);
if (ret < 0) {
pict.palette=VIDEO_PALETTE_YUV422;
ret = ioctl(video_fd, VIDIOCSPICT, &pict);
if (ret < 0) {
pict.palette=VIDEO_PALETTE_RGB24;
ret = ioctl(video_fd, VIDIOCSPICT, &pict);
if (ret < 0)
goto fail1;
}
}
}
s->frame_format = pict.palette;
val = 1;
ioctl(video_fd, VIDIOCCAPTURE, &val);
s->time_frame = av_gettime();
s->use_mmap = 0;
} else {
video_buf = mmap(0,gb_buffers.size,PROT_READ|PROT_WRITE,MAP_SHARED,video_fd,0);
if ((unsigned char*)-1 == video_buf) {
perror("mmap");
goto fail;
}
gb_frame = 0;
s->time_frame = av_gettime();
/* start to grab the first frame */
gb_buf.frame = gb_frame % gb_buffers.frames;
gb_buf.height = height;
gb_buf.width = width;
gb_buf.format = desired_palette;
if (desired_palette == -1 || (ret = ioctl(video_fd, VIDIOCMCAPTURE, &gb_buf)) < 0) {
gb_buf.format = VIDEO_PALETTE_YUV420P;
ret = ioctl(video_fd, VIDIOCMCAPTURE, &gb_buf);
if (ret < 0 && errno != EAGAIN) {
/* try YUV422 */
gb_buf.format = VIDEO_PALETTE_YUV422;
ret = ioctl(video_fd, VIDIOCMCAPTURE, &gb_buf);
if (ret < 0 && errno != EAGAIN) {
/* try RGB24 */
gb_buf.format = VIDEO_PALETTE_RGB24;
ret = ioctl(video_fd, VIDIOCMCAPTURE, &gb_buf);
}
}
}
if (ret < 0) {
if (errno != EAGAIN) {
fail1:
fprintf(stderr, "Fatal: grab device does not support suitable format\n");
} else {
fprintf(stderr,"Fatal: grab device does not receive any video signal\n");
}
goto fail;
}
s->frame_format = gb_buf.format;
s->use_mmap = 1;
}
switch(s->frame_format) {
case VIDEO_PALETTE_YUV420P:
frame_size = (width * height * 3) / 2;
st->codec.pix_fmt = PIX_FMT_YUV420P;
break;
case VIDEO_PALETTE_YUV422:
frame_size = width * height * 2;
st->codec.pix_fmt = PIX_FMT_YUV422;
break;
case VIDEO_PALETTE_RGB24:
frame_size = width * height * 3;
st->codec.pix_fmt = PIX_FMT_BGR24; /* NOTE: v4l uses BGR24, not RGB24 ! */
break;
default:
goto fail;
}
s->fd = video_fd;
s->frame_size = frame_size;
st->codec.codec_type = CODEC_TYPE_VIDEO;
st->codec.codec_id = CODEC_ID_RAWVIDEO;
st->codec.width = width;
st->codec.height = height;
st->codec.frame_rate = frame_rate;
return 0;
fail:
if (video_fd >= 0)
close(video_fd);
av_free(st);
return -EIO;
}
static int v4l_mm_read_picture(VideoData *s, UINT8 *buf)
{
UINT8 *ptr;
/* Setup to capture the next frame */
gb_buf.frame = (gb_frame + 1) % gb_buffers.frames;
if (ioctl(s->fd, VIDIOCMCAPTURE, &gb_buf) < 0) {
if (errno == EAGAIN)
fprintf(stderr,"Cannot Sync\n");
else
perror("VIDIOCMCAPTURE");
return -EIO;
}
while (ioctl(s->fd, VIDIOCSYNC, &gb_frame) < 0 &&
(errno == EAGAIN || errno == EINTR));
ptr = video_buf + gb_buffers.offsets[gb_frame];
memcpy(buf, ptr, s->frame_size);
/* This is now the grabbing frame */
gb_frame = gb_buf.frame;
return s->frame_size;
}
static int grab_read_packet(AVFormatContext *s1, AVPacket *pkt)
{
VideoData *s = s1->priv_data;
INT64 curtime, delay;
struct timespec ts;
int first;
INT64 per_frame = (INT64_C(1000000) * FRAME_RATE_BASE) / s->frame_rate;
int dropped = 0;
/* Calculate the time of the next frame */
s->time_frame += per_frame;
/* wait based on the frame rate */
for(first = 1;; first = 0) {
curtime = av_gettime();
delay = s->time_frame - curtime;
if (delay <= 0) {
if (delay < -per_frame) {
/* printf("grabbing is %d frames late (dropping)\n", (int) -(delay / 16666)); */
dropped = 1;
s->time_frame += per_frame;
}
break;
}
ts.tv_sec = delay / 1000000;
ts.tv_nsec = (delay % 1000000) * 1000;
nanosleep(&ts, NULL);
}
if (av_new_packet(pkt, s->frame_size) < 0)
return -EIO;
if (dropped)
pkt->flags |= PKT_FLAG_DROPPED_FRAME;
/* read one frame */
if (s->use_mmap) {
return v4l_mm_read_picture(s, pkt->data);
} else {
if (read(s->fd, pkt->data, pkt->size) != pkt->size)
return -EIO;
return s->frame_size;
}
}
static int grab_read_close(AVFormatContext *s1)
{
VideoData *s = s1->priv_data;
if (s->use_mmap)
munmap(video_buf, gb_buffers.size);
/* restore audio settings */
ioctl(s->fd, VIDIOCSAUDIO, &audio_saved);
close(s->fd);
return 0;
}
AVInputFormat video_grab_device_format = {
"video_grab_device",
"video grab",
sizeof(VideoData),
NULL,
grab_read_header,
grab_read_packet,
grab_read_close,
flags: AVFMT_NOFILE,
};
int video_grab_init(void)
{
av_register_input_format(&video_grab_device_format);
return 0;
}
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