File 0007-v4l2loopback-Fixup-bytesused-field-when-wr... of Package v4l2loopback

Overview Repositories Revisions Requests Users Attributes Meta

File 0007-v4l2loopback-Fixup-bytesused-field-when-writer-sends.patch of Package v4l2loopback (Revision 2402541392636f99ccc3e95bfb098e0c)

Currently displaying revision 2402541392636f99ccc3e95bfb098e0c , Show latest

From: Hans de Goede <hdegoede@redhat.com>
Date: Mon, 8 May 2023 12:08:12 +0200
Subject: v4l2loopback: Fixup bytesused field when writer sends a too large
 value

Gstreamer's v4l2sink is known to submit buffers with bytesused set to
the length of the buffer instead of the size of the actual image-data
within the buffer which is typically smaller due to buffer sizes
being rounded op to a page-size:

https://gitlab.freedesktop.org/gstreamer/gstreamer/-/issues/2532

Despite this being a long standing issue and their being 2 merge-reqs:

https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3713
https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/4527

to try and fix this it looks like this is not going to get fixed
in gst's v4l2sink anytime soon and even if once it is fixed many users
will likely be using an older v4l2sink which still has this bug.

These buffers with a too large bytes used value are causing issues
with various apps which reject these buffers when reading from
the v4l2loopback device, such as e.g. ffmpeg and firefox.

Add a pix_format_has_valid_sizeimage flag which gets set from
vidioc_s_fmt_out() if dev->pix_format.sizeimage is known to have just
been set to a valid, fixed size (so this e.g. won't be set for MJPG).

And then fix this issue by making vidioc_qbuf() truncate
V4L2_BUF_TYPE_VIDEO_OUTPUT buffer's bytes_used value to
dev->pix_format.sizeimage when this flag is set.

Closes #190
Closes #448
Obsoletes #435

(backported from commit 175adaf96d6d3784b922d3e0c77e9fd3e9ad8f53)
Signed-off-by: You-Sheng Yang <vicamo@gmail.com>
---
 v4l2loopback.c | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/v4l2loopback.c b/v4l2loopback.c
index 8d3a22c..d2e6b2f 100644
--- a/v4l2loopback.c
+++ b/v4l2loopback.c
@@ -334,6 +334,7 @@ struct v4l2_loopback_device {
 	struct video_device *vdev;
 	/* pixel and stream format */
 	struct v4l2_pix_format pix_format;
+	bool pix_format_has_valid_sizeimage;
 	struct v4l2_captureparm capture_param;
 	unsigned long frame_jiffies;
 
@@ -479,6 +480,20 @@ static void pix_format_set_size(struct v4l2_pix_format *f,
 	}
 }
 
+/* Checks if v4l2l_fill_format() has set a valid, fixed sizeimage val. */
+static bool v4l2l_pix_format_has_valid_sizeimage(struct v4l2_format *fmt)
+{
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 2, 0)
+	const struct v4l2_format_info *info;
+
+	info = v4l2_format_info(fmt->fmt.pix.pixelformat);
+	if (info && info->mem_planes == 1)
+		return true;
+#endif
+
+	return false;
+}
+
 static int set_timeperframe(struct v4l2_loopback_device *dev,
 			    struct v4l2_fract *tpf)
 {
@@ -1048,6 +1063,8 @@ static int vidioc_try_fmt_out(struct file *file, void *priv,
 
 		/* FIXXME: try_fmt should never modify the device-state */
 		dev->pix_format = fmt->fmt.pix;
+		dev->pix_format_has_valid_sizeimage =
+			v4l2l_pix_format_has_valid_sizeimage(fmt);
 	}
 	return 0;
 }
@@ -1606,7 +1623,18 @@ static int vidioc_qbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
 			v4l2l_get_timestamp(&b->buffer);
 		else
 			b->buffer.timestamp = buf->timestamp;
-		b->buffer.bytesused = buf->bytesused;
+		if (dev->pix_format_has_valid_sizeimage) {
+			if (buf->bytesused >= dev->pix_format.sizeimage) {
+				b->buffer.bytesused = dev->pix_format.sizeimage;
+			} else {
+				dev_warn_ratelimited(&dev->vdev->dev, "warning queued output buffer bytesused too small %d < %d\n",
+						     buf->bytesused, dev->pix_format.sizeimage);
+				b->buffer.bytesused = buf->bytesused;
+			}
+		} else {
+			b->buffer.bytesused = buf->bytesused;
+		}
+
 		set_done(b);
 		buffer_written(dev, b);

Places

File 0007-v4l2loopback-Fixup-bytesused-field-when-writer-sends.patch of Package v4l2loopback (Revision 2402541392636f99ccc3e95bfb098e0c)

Places