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Code Issues Releases Activity

v4l2: poll the file descriptor

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Instead of busy waiting use poll();
This commit is contained in:
Luca Barbato 2012-01-05 12:17:45 +01:00
parent b8c310cb0a
commit 0efd48dfd1
1 changed files with 15 additions and 0 deletions
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15
libavdevice/v4l2.c
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@ -36,6 +36,7 @@
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/time.h>
#include <poll.h>
#if HAVE_SYS_VIDEOIO_H
#include <sys/videoio.h>
#else
@ -48,6 +49,7 @@
#include "libavutil/parseutils.h"
#include "libavutil/pixdesc.h"
#include "libavutil/avstring.h"
#include "libavutil/mathematics.h"
static const int desired_video_buffers = 256;
@ -61,6 +63,7 @@ struct video_data {
int frame_format; /* V4L2_PIX_FMT_* */
int width, height;
int frame_size;
int timeout;
int interlaced;
int top_field_first;
@ -436,12 +439,20 @@ static int mmap_read_frame(AVFormatContext *ctx, AVPacket *pkt)
struct video_data *s = ctx->priv_data;
struct v4l2_buffer buf;
struct buff_data *buf_descriptor;
struct pollfd p = { .fd = s->fd, .events = POLLIN };
int res;
memset(&buf, 0, sizeof(struct v4l2_buffer));
buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
buf.memory = V4L2_MEMORY_MMAP;
res = poll(&p, 1, s->timeout);
if (res < 0)
return AVERROR(errno);
if (!(p.revents & (POLLIN | POLLERR | POLLHUP)))
return AVERROR(EAGAIN);
/* FIXME: Some special treatment might be needed in case of loss of signal... */
while ((res = ioctl(s->fd, VIDIOC_DQBUF, &buf)) < 0 && (errno == EINTR));
if (res < 0) {
@ -635,6 +646,10 @@ static int v4l2_set_parameters(AVFormatContext *s1, AVFormatParameters *ap)
s1->streams[0]->codec->time_base.den = tpf->denominator;
s1->streams[0]->codec->time_base.num = tpf->numerator;
s->timeout = 100 +
av_rescale_q(1, s1->streams[0]->codec->time_base,
(AVRational){1, 1000});
return 0;
}