On Thu 31 January 2013 11:08:07 Mauro Carvalho Chehab wrote: > Em Thu, 31 Jan 2013 08:16:39 +0100 > Hans Verkuil <hverkuil@xxxxxxxxx> escreveu: > > > On Wed January 30 2013 20:07:29 Mauro Carvalho Chehab wrote: > > > Em Wed, 30 Jan 2013 10:49:25 +0100 > > > Hans Verkuil <hverkuil@xxxxxxxxx> escreveu: > > > > > > > On Wed 30 January 2013 10:40:30 Mauro Carvalho Chehab wrote: > > > > > Em Wed, 30 Jan 2013 09:01:22 +0100 > > > > > Hans Verkuil <hverkuil@xxxxxxxxx> escreveu: > > > > > > > > > > > This was part of my original em28xx patch series. That particular patch > > > > > > combined two things: this fix and the change where TRY_FMT would no > > > > > > longer return -EINVAL for unsupported pixelformats. The latter change was > > > > > > rejected (correctly), but we all forgot about the second part of the patch > > > > > > which fixed a real bug. I'm reposting just that fix. > > > > > > > > > > > > Changes since v1: > > > > > > > > > > > > - v1 still miscalculated the bytesperline and imagesize values (they were > > > > > > too large). > > > > > > - G_FMT had the same calculation bug. > > > > > > > > > > > > Tested with my em28xx. > > > > > > > > > > > > Regards, > > > > > > > > > > > > Hans > > > > > > > > > > > > The bytesperline calculation was incorrect: it used the old width instead of > > > > > > the provided width in the case of TRY_FMT, and it miscalculated the bytesperline > > > > > > value for the depth == 12 (planar YUV 4:1:1) case. For planar formats the > > > > > > bytesperline value should be the bytesperline of the widest plane, which is > > > > > > the Y plane which has 8 bits per pixel, not 12. > > > > > > > > > > > > Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx> > > > > > > --- > > > > > > drivers/media/usb/em28xx/em28xx-video.c | 8 ++++---- > > > > > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > > > > > > > > > diff --git a/drivers/media/usb/em28xx/em28xx-video.c b/drivers/media/usb/em28xx/em28xx-video.c > > > > > > index 2eabf2a..6ced426 100644 > > > > > > --- a/drivers/media/usb/em28xx/em28xx-video.c > > > > > > +++ b/drivers/media/usb/em28xx/em28xx-video.c > > > > > > @@ -837,8 +837,8 @@ static int vidioc_g_fmt_vid_cap(struct file *file, void *priv, > > > > > > f->fmt.pix.width = dev->width; > > > > > > f->fmt.pix.height = dev->height; > > > > > > f->fmt.pix.pixelformat = dev->format->fourcc; > > > > > > - f->fmt.pix.bytesperline = (dev->width * dev->format->depth + 7) >> 3; > > > > > > - f->fmt.pix.sizeimage = f->fmt.pix.bytesperline * dev->height; > > > > > > + f->fmt.pix.bytesperline = dev->width * (dev->format->depth >> 3); > > > > > > > > > > Why did you remove the round up here? > > > > > > > > Because that would give the wrong result. Depth can be 8, 12 or 16. The YUV 4:1:1 > > > > planar format is the one with depth 12. But for the purposes of the bytesperline > > > > calculation only the depth of the largest plane counts, which is the luma plane > > > > with a depth of 8. So for a width of 720 the value of bytesperline should be: > > > > > > > > depth=8 -> bytesperline = 720 > > > > depth=12 -> bytesperline = 720 > > > > > > With depth=12, it should be, instead, 1080, as 2 pixels need 3 bytes. > > > > No, it's not. It's a *planar* format: first the Y plane, then the two smaller > > chroma planes. The spec says that bytesperline for planar formats refers to > > the largest plane. > > > > For this format the luma plane is one byte per pixel. Each of the two chroma > > planes have effectively two bits per pixel (actually one byte per four pixels), > > so you end up with 8+2+2=12 bits per pixel. > > > > Hence bytesperline should be 720 for this particular format. > > If I understood what you just said, you're talking that the only format marked > as depth=12 is actually depth=8, right? Then the fix would be to change depth > in the table, and not here. > > Yet, I'm not sure if this is the proper fix. > > The only used I saw on userspace apps for this field is to allocate size for > the memory buffer. Some userspace applications use to get bytesperline and > multiply by the image height and get the image size, instead of relying > on sizeimage, as some drivers didn't use to fill sizeimage properly. > > By using bytesperline equal to 1080 in this case warrants that the buffers > on userspace will have enough space. I did some research into planar formats in our drivers and (of course) it's a big mess. I looked at drivers that support V4L2_PIX_FMT_YUV422P, which is fairly common: s5p-fimc: follows the spec arv: follows the spec vpif_capture: follows the spec vpif_display: follows the spec pxa_camera: no idea, I can't figure this out s3c-camif: follows the spec exynos-gsc: uses depth s2255: uses depth usbvision: uses depth saa7146: uses depth saa7134: uses depth bttv: follows the spec I think we should follow the spec here. In practice, nobody uses planar formats for consumer-type hardware as it is a very awkward format, and libv4l doesn't support it either. Since there is no clear common practice in our drivers, I'd say we stick to the spec. Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
