[PATCH v2] media: vivid: Improve timestamping
From: Gabriel Francisco Mandaji
Date: Sun Oct 21 2018 - 19:00:36 EST
Simulate a more precise timestamp by calculating it based on the
current framerate.
Signed-off-by: Gabriel Francisco Mandaji <gfmandaji@xxxxxxxxx>
---
Changes in v2:
- fix spelling
- end of exposure is offset by 90% of the frame period
- fix timestamp calculation for FIELD_ALTERNATE (untested)
- timestamp is now calculated and set from vivid_thread_cap_tick()
- capture vbi uses the same timestamp as non-vbi, but offset by 5%
- timestamp stays consistent even if the FPS changes
- tested with dropped frames
If 'Start of Exposure'/'End of Frame' changes mid-capture, it will be
completely ignored. If that's an issue, I'll change how the frame
period and cap_stream_start are calculated.
Also, should I modify the output's timestamp on this patch or on a
separated one?
---
drivers/media/platform/vivid/vivid-core.h | 2 +
drivers/media/platform/vivid/vivid-kthread-cap.c | 47 +++++++++++++++++-------
drivers/media/platform/vivid/vivid-vbi-cap.c | 4 --
3 files changed, 35 insertions(+), 18 deletions(-)
diff --git a/drivers/media/platform/vivid/vivid-core.h b/drivers/media/platform/vivid/vivid-core.h
index cd4c823..ba6fb3a 100644
--- a/drivers/media/platform/vivid/vivid-core.h
+++ b/drivers/media/platform/vivid/vivid-core.h
@@ -384,6 +384,8 @@ struct vivid_dev {
/* thread for generating video capture stream */
struct task_struct *kthread_vid_cap;
unsigned long jiffies_vid_cap;
+ u64 cap_stream_start;
+ u64 cap_frame_period;
u32 cap_seq_offset;
u32 cap_seq_count;
bool cap_seq_resync;
diff --git a/drivers/media/platform/vivid/vivid-kthread-cap.c b/drivers/media/platform/vivid/vivid-kthread-cap.c
index f06003b..828a58c 100644
--- a/drivers/media/platform/vivid/vivid-kthread-cap.c
+++ b/drivers/media/platform/vivid/vivid-kthread-cap.c
@@ -425,12 +425,6 @@ static void vivid_fillbuff(struct vivid_dev *dev, struct vivid_buffer *buf)
is_loop = true;
buf->vb.sequence = dev->vid_cap_seq_count;
- /*
- * Take the timestamp now if the timestamp source is set to
- * "Start of Exposure".
- */
- if (dev->tstamp_src_is_soe)
- buf->vb.vb2_buf.timestamp = ktime_get_ns();
if (dev->field_cap == V4L2_FIELD_ALTERNATE) {
/*
* 60 Hz standards start with the bottom field, 50 Hz standards
@@ -554,14 +548,6 @@ static void vivid_fillbuff(struct vivid_dev *dev, struct vivid_buffer *buf)
}
}
}
-
- /*
- * If "End of Frame" is specified at the timestamp source, then take
- * the timestamp now.
- */
- if (!dev->tstamp_src_is_soe)
- buf->vb.vb2_buf.timestamp = ktime_get_ns();
- buf->vb.vb2_buf.timestamp += dev->time_wrap_offset;
}
/*
@@ -667,10 +653,27 @@ static void vivid_overlay(struct vivid_dev *dev, struct vivid_buffer *buf)
}
}
+static void vivid_cap_update_frame_period(struct vivid_dev *dev)
+{
+ u64 f_period = dev->timeperframe_vid_cap.numerator * 1000000000 /
+ dev->timeperframe_vid_cap.denominator;
+ if (dev->field_cap == V4L2_FIELD_ALTERNATE)
+ f_period /= 2;
+ /*
+ * If "End of Frame", then calculate the exposure time as 0.9
+ * of the frame period.
+ */
+ if (!dev->tstamp_src_is_soe)
+ f_period += f_period / 10 * 9;
+
+ dev->cap_frame_period = f_period;
+}
+
static void vivid_thread_vid_cap_tick(struct vivid_dev *dev, int dropped_bufs)
{
struct vivid_buffer *vid_cap_buf = NULL;
struct vivid_buffer *vbi_cap_buf = NULL;
+ u64 f_time = 0;
dprintk(dev, 1, "Video Capture Thread Tick\n");
@@ -702,6 +705,9 @@ static void vivid_thread_vid_cap_tick(struct vivid_dev *dev, int dropped_bufs)
if (!vid_cap_buf && !vbi_cap_buf)
goto update_mv;
+ f_time = dev->cap_frame_period * dev->vid_cap_seq_count +
+ dev->cap_stream_start + dev->time_wrap_offset;
+
if (vid_cap_buf) {
/* Fill buffer */
vivid_fillbuff(dev, vid_cap_buf);
@@ -717,9 +723,13 @@ static void vivid_thread_vid_cap_tick(struct vivid_dev *dev, int dropped_bufs)
VB2_BUF_STATE_ERROR : VB2_BUF_STATE_DONE);
dprintk(dev, 2, "vid_cap buffer %d done\n",
vid_cap_buf->vb.vb2_buf.index);
+
+ vid_cap_buf->vb.vb2_buf.timestamp = f_time;
}
if (vbi_cap_buf) {
+ u64 vbi_period;
+
if (dev->stream_sliced_vbi_cap)
vivid_sliced_vbi_cap_process(dev, vbi_cap_buf);
else
@@ -728,6 +738,10 @@ static void vivid_thread_vid_cap_tick(struct vivid_dev *dev, int dropped_bufs)
VB2_BUF_STATE_ERROR : VB2_BUF_STATE_DONE);
dprintk(dev, 2, "vbi_cap %d done\n",
vbi_cap_buf->vb.vb2_buf.index);
+
+ /* If capturing a VBI, offset by 0.05 */
+ vbi_period = dev->cap_frame_period / 100 * 5;
+ vbi_cap_buf->vb.vb2_buf.timestamp = f_time + vbi_period;
}
dev->dqbuf_error = false;
@@ -759,6 +773,8 @@ static int vivid_thread_vid_cap(void *data)
dev->cap_seq_count = 0;
dev->cap_seq_resync = false;
dev->jiffies_vid_cap = jiffies;
+ dev->cap_stream_start = ktime_get_ns();
+ vivid_cap_update_frame_period(dev);
for (;;) {
try_to_freeze();
@@ -771,6 +787,9 @@ static int vivid_thread_vid_cap(void *data)
dev->jiffies_vid_cap = cur_jiffies;
dev->cap_seq_offset = dev->cap_seq_count + 1;
dev->cap_seq_count = 0;
+ dev->cap_stream_start += dev->cap_frame_period *
+ dev->cap_seq_offset;
+ vivid_cap_update_frame_period(dev);
dev->cap_seq_resync = false;
}
numerator = dev->timeperframe_vid_cap.numerator;
diff --git a/drivers/media/platform/vivid/vivid-vbi-cap.c b/drivers/media/platform/vivid/vivid-vbi-cap.c
index 92a8529..c7cacc6 100644
--- a/drivers/media/platform/vivid/vivid-vbi-cap.c
+++ b/drivers/media/platform/vivid/vivid-vbi-cap.c
@@ -95,8 +95,6 @@ void vivid_raw_vbi_cap_process(struct vivid_dev *dev, struct vivid_buffer *buf)
if (!VIVID_INVALID_SIGNAL(dev->std_signal_mode))
vivid_vbi_gen_raw(&dev->vbi_gen, &vbi, vbuf);
-
- buf->vb.vb2_buf.timestamp = ktime_get_ns() + dev->time_wrap_offset;
}
@@ -119,8 +117,6 @@ void vivid_sliced_vbi_cap_process(struct vivid_dev *dev,
for (i = 0; i < 25; i++)
vbuf[i] = dev->vbi_gen.data[i];
}
-
- buf->vb.vb2_buf.timestamp = ktime_get_ns() + dev->time_wrap_offset;
}
static int vbi_cap_queue_setup(struct vb2_queue *vq,
--
1.9.1