1) Use v4l2_mmap.
2) Use libv4lconvert for sample conversion.
That implementation is heavily copied from v4l2grab application:
v4l2grab.c (C) 2009 Mauro Carvalho Chehab
Signed-off-by: Antti Palosaari <crope@xxxxxx>
---
lib/libv4l2_x_impl.cc | 120 +++++++++++++++++++++++++++++++++++++++++++++-----
lib/libv4l2_x_impl.h | 7 +++
2 files changed, 116 insertions(+), 11 deletions(-)
diff --git a/lib/libv4l2_x_impl.cc b/lib/libv4l2_x_impl.cc
index 3362044..c726ffc 100644
--- a/lib/libv4l2_x_impl.cc
+++ b/lib/libv4l2_x_impl.cc
@@ -24,6 +24,8 @@
#include <gr_io_signature.h>
#include "libv4l2_x_impl.h"
+#include <sys/mman.h>
+#include <linux/videodev2.h>
/* Control classes */
#define V4L2_CTRL_CLASS_USER 0x00980000 /* Old-style 'user' controls */
@@ -39,6 +41,21 @@
#define CID_TUNER_IF ((V4L2_CID_USER_BASE | 0xf000) + 12)
#define CID_TUNER_GAIN ((V4L2_CID_USER_BASE | 0xf000) + 13)
+#define CLEAR(x) memset(&(x), 0, sizeof(x))
+
+static void xioctl(int fh, unsigned long int request, void *arg)
+{
+ int ret;
+
+ do {
+ ret = v4l2_ioctl(fh, request, arg);
+ } while (ret == -1 && ((errno == EINTR) || (errno == EAGAIN)));
+ if (ret == -1) {
+ fprintf(stderr, "error %d, %s\n", errno, strerror(errno));
+ exit(EXIT_FAILURE);
+ }
+}
+
namespace gr {
namespace kernel {
@@ -56,11 +73,64 @@ namespace gr {
gr_make_io_signature(0, 0, 0),
gr_make_io_signature(1, 1, sizeof (gr_complex)))
{
+ struct v4l2_format fmt;
+ struct v4l2_buffer buf;
+ struct v4l2_requestbuffers req;
+ enum v4l2_buf_type type;
+ unsigned int i;
+
fd = v4l2_open(filename, O_RDWR | O_NONBLOCK, 0);
if (fd < 0) {
- perror(filename);
- throw std::runtime_error("can't open file");
+ perror("Cannot open device");
+ exit(EXIT_FAILURE);
+ }
+
+ CLEAR(fmt);
+ fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+ fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_FLOAT;
+ xioctl(fd, VIDIOC_S_FMT, &fmt);
+ if (fmt.fmt.pix.pixelformat != V4L2_PIX_FMT_FLOAT) {
+ printf("Libv4l didn't accept FLOAT format. Cannot proceed. Pixelformat %4.4s\n",
+ (char *)&fmt.fmt.pix.pixelformat);
+ exit(EXIT_FAILURE);
+ }
+
+ CLEAR(req);
+ req.count = 8;
+ req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+ req.memory = V4L2_MEMORY_MMAP;
+ xioctl(fd, VIDIOC_REQBUFS, &req);
+
+ buffers = (struct buffer*) calloc(req.count, sizeof(*buffers));
+ for (n_buffers = 0; n_buffers < req.count; n_buffers++) {
+ CLEAR(buf);
+ buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+ buf.memory = V4L2_MEMORY_MMAP;
+ buf.index = n_buffers;
+ xioctl(fd, VIDIOC_QUERYBUF, &buf);
+
+ buffers[n_buffers].length = buf.length;
+ buffers[n_buffers].start = v4l2_mmap(NULL, buf.length,
+ PROT_READ | PROT_WRITE, MAP_SHARED,
+ fd, buf.m.offset);
+
+ if (buffers[n_buffers].start == MAP_FAILED) {
+ perror("mmap");
+ exit(EXIT_FAILURE);
+ }
}
+
+ for (i = 0; i < n_buffers; i++) {
+ CLEAR(buf);
+ buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+ buf.memory = V4L2_MEMORY_MMAP;
+ buf.index = i;
+ xioctl(fd, VIDIOC_QBUF, &buf);
+ }
+
+ // start streaming
+ type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+ xioctl(fd, VIDIOC_STREAMON, &type);
}
/*
@@ -68,8 +138,17 @@ namespace gr {
*/
libv4l2_x_impl::~libv4l2_x_impl()
{
- if (fd > 0)
- v4l2_close(fd);
+ unsigned int i;
+ enum v4l2_buf_type type;
+
+ // stop streaming
+ type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+ xioctl(fd, VIDIOC_STREAMOFF, &type);
+
+ for (i = 0; i < n_buffers; i++)
+ v4l2_munmap(buffers[i].start, buffers[i].length);
+
+ v4l2_close(fd);
}
void
@@ -156,17 +235,36 @@ namespace gr {
gr_vector_void_star &output_items)
{
gr_complex *out = (gr_complex *) output_items[0];
- int ret, errors = 0, i;
+ int ret;
+ struct timeval tv;
+ struct v4l2_buffer buf;
+ fd_set fds;
// Read data from device
- ret = v4l2_read(fd, out, noutput_items * sizeof (gr_complex));
+ do {
+ FD_ZERO(&fds);
+ FD_SET(fd, &fds);
+
+ // Timeout
+ tv.tv_sec = 2;
+ tv.tv_usec = 0;
+
+ ret = select(fd + 1, &fds, NULL, NULL, &tv);
+ } while ((ret == -1 && (errno = EINTR)));
+ if (ret == -1) {
+ perror("select");
+ return errno;
+ }
- // Tell runtime system how many output items we produced.
- if (ret > 0)
- ret = ret / sizeof (gr_complex);
- else
- ret = 0;
+ CLEAR(buf);
+ buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+ buf.memory = V4L2_MEMORY_MMAP;
+ xioctl(fd, VIDIOC_DQBUF, &buf);
+ memcpy(out, buffers[buf.index].start, buf.bytesused);
+ ret = buf.bytesused / sizeof (gr_complex);
+ xioctl(fd, VIDIOC_QBUF, &buf);
+ // Tell runtime system how many output items we produced.
return ret;
}
diff --git a/lib/libv4l2_x_impl.h b/lib/libv4l2_x_impl.h
index 276a64f..e0439b3 100644
--- a/lib/libv4l2_x_impl.h
+++ b/lib/libv4l2_x_impl.h
@@ -25,12 +25,19 @@
namespace gr {
namespace kernel {
+ // v4l2_mmap
+ struct buffer {
+ void *start;
+ size_t length;
+ };
class libv4l2_x_impl : public libv4l2_x
{
private:
// v4l2 device file handle
int fd;
+ struct buffer *buffers;
+ unsigned int n_buffers;
public:
libv4l2_x_impl(const char *filename);
--
1.8.4.2
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