Skip to content

Commit

Permalink
'sustain_framerate' ctrl
Browse files Browse the repository at this point in the history
  • Loading branch information
@an146
an146 committed Mar 17, 2012
1 parent d617618 commit d7b102d
Showing 1 changed file with 116 additions and 21 deletions.
137 changes: 116 additions & 21 deletions v4l2loopback.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -105,6 +105,7 @@ MODULE_PARM_DESC(video_nr, "video device numbers (-1=auto, 0=/dev/video0, etc.)"

/* control IDs */
#define CID_KEEP_FORMAT (V4L2_CID_PRIVATE_BASE+0)
#define CID_SUSTAIN_FRAMERATE (V4L2_CID_PRIVATE_BASE+1)


/* module structures */
Expand Down Expand Up @@ -132,6 +133,7 @@ struct v4l2_loopback_device {

/* ctrls */
int keep_format; /* stay ready_for_capture when all openers close() */
int sustain_framerate; /* duplicate frames to maintain ~nominal framerate */

/* buffers stuff */
u8 *image; /* pointer to actual buffers data */
Expand All @@ -144,11 +146,16 @@ struct v4l2_loopback_device {
int write_position; /* number of last written frame + 1 */
long buffer_size;

/* sustain_framerate stuff */
struct timer_list sustain_timer;
unsigned int reread_count;

/* sync stuff */
atomic_t open_count;
int ready_for_capture;/* set to true when at least one writer opened
* device and negotiated format */
wait_queue_head_t read_event;
spinlock_t lock;
};

/* types of opener shows what opener wants to do with loopback */
Expand All @@ -164,6 +171,7 @@ struct v4l2_loopback_opener {
int vidioc_enum_frameintervals_calls;
int read_position; /* number of last processed frame + 1 or
* write_position - 1 if reader went out of sync */
unsigned int reread_count;
struct v4l2_buffer *buffers;
int buffers_number; /* should not be big, 4 is a good choice */
};
Expand Down Expand Up @@ -484,6 +492,7 @@ static void init_buffers(struct v4l2_loopback_device *dev);
static int allocate_buffers(struct v4l2_loopback_device *dev);
static int free_buffers(struct v4l2_loopback_device *dev);
static void try_free_buffers(struct v4l2_loopback_device *dev);
static void check_timers(struct v4l2_loopback_device *dev);
static const struct v4l2_file_operations v4l2_loopback_fops;
static const struct v4l2_ioctl_ops v4l2_loopback_ioctl_ops;

Expand Down Expand Up @@ -1041,6 +1050,7 @@ vidioc_queryctrl(struct file *file, void *fh,
{
switch (q->id) {
case CID_KEEP_FORMAT:
case CID_SUSTAIN_FRAMERATE:
q->type = V4L2_CTRL_TYPE_BOOLEAN;
q->minimum = 0;
q->maximum = 1;
Expand All @@ -1055,6 +1065,10 @@ vidioc_queryctrl(struct file *file, void *fh,
strcpy(q->name, "keep_format");
q->default_value = 0;
break;
case CID_SUSTAIN_FRAMERATE:
strcpy(q->name, "sustain_framerate");
q->default_value = 0;
break;
default:
BUG();
}
Expand All @@ -1074,6 +1088,9 @@ vidioc_g_ctrl(struct file *file, void *fh,
case CID_KEEP_FORMAT:
c->value = dev->keep_format;
break;
case CID_SUSTAIN_FRAMERATE:
c->value = dev->sustain_framerate;
break;
default:
return -EINVAL;
}
Expand All @@ -1095,6 +1112,14 @@ vidioc_s_ctrl(struct file *file, void *fh,
dev->keep_format = c->value;
try_free_buffers(dev);
break;
case CID_SUSTAIN_FRAMERATE:
if (c->value < 0 || c->value > 1)
return -EINVAL;
spin_lock_bh(&dev->lock);
dev->sustain_framerate = c->value;
check_timers(dev);
spin_unlock_bh(&dev->lock);
break;
default:
return -EINVAL;
}
Expand Down Expand Up @@ -1304,6 +1329,17 @@ vidioc_querybuf (struct file *file,
return 0;
}

static void
buffer_written(struct v4l2_loopback_device *dev)
{
del_timer_sync(&dev->sustain_timer);
spin_lock_bh(&dev->lock);
++dev->write_position;
dev->reread_count = 0;
check_timers(dev);
spin_unlock_bh(&dev->lock);
}

/* put buffer to queue
* called on VIDIOC_QBUF
*/
Expand Down Expand Up @@ -1333,13 +1369,54 @@ vidioc_qbuf (struct file *file,
dprintkrw("output QBUF index: %d\n", index);
do_gettimeofday(&b->buffer.timestamp);
set_done(b);
buffer_written(dev);
wake_up_all(&dev->read_event);
return 0;
default:
return -EINVAL;
}
}

static int
can_read(struct v4l2_loopback_device *dev, struct v4l2_loopback_opener *opener)
{
int ret;
spin_lock_bh(&dev->lock);
check_timers(dev);
ret = dev->write_position > opener->read_position || dev->reread_count > opener->reread_count;
spin_unlock_bh(&dev->lock);
return ret;
}

static int
get_capture_buffer(struct file *file)
{
struct v4l2_loopback_device *dev = v4l2loopback_getdevice(file);
struct v4l2_loopback_opener *opener = file->private_data;
int ret;

if ((file->f_flags&O_NONBLOCK) && (dev->write_position <= opener->read_position &&
dev->reread_count <= opener->reread_count))
return -EAGAIN;
wait_event_interruptible(dev->read_event, can_read(dev, opener));

spin_lock_bh(&dev->lock);
if (dev->write_position == opener->read_position) {
if (dev->reread_count > opener->reread_count+2)
opener->reread_count = dev->reread_count - 1;
++opener->reread_count;
ret = opener->read_position % dev->used_buffers;
} else {
opener->reread_count = 0;
if (dev->write_position > opener->read_position+2)
opener->read_position = dev->write_position - 1;
ret = opener->read_position++ % dev->used_buffers;
}
spin_unlock_bh(&dev->lock);

return ret;
}

/* put buffer to dequeue
* called on VIDIOC_DQBUF
*/
Expand All @@ -1357,20 +1434,14 @@ vidioc_dqbuf (struct file *file,

switch (buf->type) {
case V4L2_BUF_TYPE_VIDEO_CAPTURE:
if ((dev->write_position <= opener->read_position) &&
(file->f_flags&O_NONBLOCK))
return -EAGAIN;
wait_event_interruptible(dev->read_event, (dev->write_position >
opener->read_position));
if (dev->write_position > opener->read_position+2)
opener->read_position = dev->write_position - 1;
index = opener->read_position % dev->used_buffers;
index = get_capture_buffer(file);
if (index < 0)
return index;
dprintkrw("capture DQBUF index: %d\n", index);
if (!(dev->buffers[index].buffer.flags&V4L2_BUF_FLAG_MAPPED)) {
dprintk("trying to return not mapped buf\n");
return -EINVAL;
}
++opener->read_position;
unset_flags(&dev->buffers[index]);
*buf = dev->buffers[index].buffer;
return 0;
Expand Down Expand Up @@ -1591,7 +1662,7 @@ v4l2_loopback_poll (struct file *file,
break;
case READER:
poll_wait(file, &dev->read_event, pts);
if (dev->write_position > opener->read_position)
if (can_read(dev, opener))
ret_mask = POLLIN | POLLRDNORM;
break;
default:
Expand Down Expand Up @@ -1636,6 +1707,8 @@ v4l2_loopback_close (struct file *file)
dev = v4l2loopback_getdevice(file);

atomic_dec(&dev->open_count);
if (dev->open_count.counter == 0)
del_timer_sync(&dev->sustain_timer);
try_free_buffers(dev);
kfree(opener);
MARK();
Expand All @@ -1656,24 +1729,15 @@ v4l2_loopback_read (struct file *file,
opener = file->private_data;
dev = v4l2loopback_getdevice(file);

if ((dev->write_position <= opener->read_position) &&
(file->f_flags&O_NONBLOCK)) {
return -EAGAIN;
}
wait_event_interruptible(dev->read_event,
(dev->write_position > opener->read_position));
read_index = get_capture_buffer(file);
if (count > dev->buffer_size)
count = dev->buffer_size;
if (dev->write_position > opener->read_position+2)
opener->read_position = dev->write_position - 1;
read_index = opener->read_position % dev->used_buffers;
if (copy_to_user((void *) buf, (void *) (dev->image +
dev->buffers[read_index].buffer.m.offset), count)) {
printk(KERN_ERR "v4l2-loopback: "
"failed copy_from_user() in write buf\n");
return -EFAULT;
}
++opener->read_position;
dprintkrw("leave v4l2_loopback_read()\n");
return count;
}
Expand Down Expand Up @@ -1714,7 +1778,8 @@ v4l2_loopback_write (struct file *file,
return -EFAULT;
}
do_gettimeofday(&b->timestamp);
b->sequence = dev->write_position++;
b->sequence = dev->write_position;
buffer_written(dev);
wake_up_all(&dev->read_event);
dprintkrw("leave v4l2_loopback_write()\n");
return count;
Expand Down Expand Up @@ -1840,6 +1905,33 @@ init_capture_param (struct v4l2_captureparm *capture_param)
capture_param->timeperframe.denominator = 30;
}

static void
check_timers(struct v4l2_loopback_device *dev)
{
if (!dev->ready_for_capture)
return;

if (dev->sustain_framerate && !timer_pending(&dev->sustain_timer))
mod_timer(&dev->sustain_timer, jiffies + dev->frame_jiffies * 3 / 2);
}

static void
sustain_timer_clb(unsigned long nr)
{
struct v4l2_loopback_device *dev = devs[nr];
spin_lock(&dev->lock);
if (dev->sustain_framerate) {
dev->reread_count++;
dprintkrw("reread: %d %d", dev->write_position, dev->reread_count);
if (dev->reread_count == 1)
mod_timer(&dev->sustain_timer, jiffies + max(1UL, dev->frame_jiffies / 2));
else
mod_timer(&dev->sustain_timer, jiffies + dev->frame_jiffies);
wake_up_all(&dev->read_event);
}
spin_unlock(&dev->lock);
}

/* init loopback main structure */
static int
v4l2_loopback_init (struct v4l2_loopback_device *dev,
Expand All @@ -1861,6 +1953,7 @@ v4l2_loopback_init (struct v4l2_loopback_device *dev,
init_capture_param(&dev->capture_param);
set_timeperframe(dev, &dev->capture_param.timeperframe);
dev->keep_format = 0;
dev->sustain_framerate = 0;
dev->buffers_number = max_buffers;
dev->used_buffers = max_buffers;
dev->max_openers = max_openers;
Expand All @@ -1869,6 +1962,8 @@ v4l2_loopback_init (struct v4l2_loopback_device *dev,
dev->buffer_size = 0;
dev->image = NULL;
dev->imagesize = 0;
setup_timer(&dev->sustain_timer, sustain_timer_clb, nr);
dev->reread_count = 0;

/* FIXME set buffers to 0 */

Expand Down

0 comments on commit d7b102d

Please sign in to comment.