Hi Alex On Thu, 3 Nov 2022 at 09:09, Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx> wrote: > > Hi Dave, > > Am Dienstag, 1. November 2022, 19:20:47 CET schrieb Dave Stevenson: > > Hi Alexander > > > > On Tue, 1 Nov 2022 at 15:04, Alexander Stein > > > > <alexander.stein@xxxxxxxxxxxxxxx> wrote: > > > Hi Dave, > > > > > > thanks for the fast reply. > > > > > > Am Dienstag, 1. November 2022, 14:47:16 CET schrieb Dave Stevenson: > > > > Hi Alexander > > > > > > > > On Tue, 1 Nov 2022 at 11:59, Alexander Stein > > > > > > > > <alexander.stein@xxxxxxxxxxxxxxx> wrote: > > As per the docs link, raw sensors will be using the HBLANK and VBLANK > > controls, not VIDIOC_S_PARM. > > I don't know whether the GStreamer folks wish to add support to > > v4l2src to set those - libcamerasrc is going to be the more normal > > user of these sensors, but that generally means needing an ISP of some > > form. With just v4l2src you've got no AE / AGC control loops, so it is > > only of use in controlled lighting conditions. > > I am aware that v4l2src is rather some raw accessor to cameras. What video > format is libcamerasrc supposed to provide? Raw formats (Y8, bayer patterns) > or already converted to RBGA etc.? It depends on the pipeline handler. Raw streams will be the unprocessed images from the sensor, so typically Bayer or mono. Processed streams depend on the ISP capabilities, but generally YUV or RGB/RGBx. > > I don't know the full details of the imx8 range, but believe the > > libcamera folk were working with one of the imx8 platforms. > > If an ISP is required then it will probably be imx8mp. > > > > > I'm assuming you're not using Media Controller either, as v4l2src > > > > won't set up Media Controller links correctly either. > > > > > > Well, actually I am using Media Controller. But I need to configure it > > > before gstreamer usage. There is no specific reason for gstreamer, but we > > > use this to verify features on downstream kernel. > > > <snip> > > > Mh, using v4l2-ctl --set-ctrl=vertical_blanking=344 -d /dev/v4l-subdev2 I > > > get 109.61fps for 1280x800. > > > > The sensor has an external clock signal (XVCLK) which can be between 6 > > and 27MHz. The driver only supports 24MHz. Is your module using a > > 24MHz clock? > > Well, I assume it is. We are using an OV9281 camera from vision components. Thank you - I happen to have one of those, so I can test. (I also have OV9281 modules from InnoVision, Arducam, and possibly others). Vision Components modules do have the joys of not being able to do a 16bit read. > > > > I don't recall where I'd got the 200MPix/s value from - it's not > > > > documented in the datasheet, but presumably from 160 * 10 / 8 > > > > (switching from 10 to 8 bits at the same output rate). You're the > > > > first to notice the rates are off, although at least it's less than > > > > the factor of two that this driver used to be out by. > > > > > > I admit I'm not fully sure which results are correct and what they are > > > > > > expected to be. But here are some results using the v4l-ctrl approach: > > > | 1280x800 | 1280x720 | 640x400 | > > > > > > -----+----------+----------+---------+ > > > GREY | 68.84 | 72.0 | 73.50 | > > > Y10 | 57.37 | 60.0 | 73.50 | > > > > > > All using their default vertical and horizontal blanking. Especially > > > switching to 640x400 and then back to 1280x720 leaves the > > > horizontal_blanking to the old (640) value, resulting in lower frame > > > rates. > > > > IMHO This isn't clear in the docs. > > My understanding is that controls shouldn't change value when changing > > modes unless the new mode requires updating the range for the control > > such that the current value is invalid. This does mean that the > > framerate will change if you change modes without reprogramming, but > > what heuristics should be used if you did update it? > > For 1280 the default horizontal_blanking is 250, but when changing to 640 the > minimum also increased to 890. When switching back horizontal_blanking stays > at 890, as it is still a valid value. > > > Options: > > 1) retain the current frame rate by recomputing VBLANK, but there will > > be conditions where you can't achieve the same frame rate in all > > modes. > > 2) reset to a default frame rate, but how do you define that? Do you > > have to detect change of mode vs just calling S_FMT with the same > > mode? > > 3) adjust the limits but otherwise leave the control alone. > > 4) as 3, but update the default value to reflect some standard > > framerate (but how do you define that standard?) > > > > Different sensors are currently doing different things, so the only > > approach you can really take is for userspace to set the controls > > explicitly after setting a mode. > > I'm not sure what is the best way to go, all options have different use cases > in mind. At least one should be aware that some controls might change when > switching modes. Switching is the interesting part. I had an annoyance trying to test variable HBLANK support on imx290 before libcamera supported it. libcamera (at least on the Pi) always explicitly sets the mode when run, therefore the HBLANK I was setting was always being reset due to s_fmt being called on the driver, hence my comment above about detecting a change of mode or not. Without any definition of the correct behaviour you find different drivers do different things, and userspace has to handle all parameters or suffer unexpected results :-( > > Sakari will normally point to the CCS driver as a model for raw > > sensors, and that appears to adopt option 3. There was a thread with > > Jacopo recently over this same subject, but no resolution. I think it > > was on the ar0521 patchset. > > > > Clean boot and testing in this order: > > - 1280x720 Y10P 63.05fps > > - 1280x800 Y10P 60.28fps > > - 640x400 Y10P 77.22fps > > Reboot so that the HBLANK change is reset > > - 1280x720 GREY 75.65fps > > - 1280x800 GREY 72.33fps > > - 640x400 GREY 92.67fps. Tested with my Vision Components OV9281, and I get identical numbers to those above. > > I don't believe your GREY 640x400 number as it's the same as your > > 640x400 Y10 value, but all your other values except 1280x800 Y10 > > differ from mine by a factor of 1.0507. (1280x800 Y10 is x1.099). > > I'd suggest measuring your XVCLK clock signal with an oscilloscope or > > frequency counter as I suspect it isn't 24MHz. 22.8MHz would give > > these results, but is a slightly strange frequency if from a dedicated > > oscillator rather than a PLL. > > I lack technical documentation for the camera hardware module, so I do not see > a way to actually measuring XVCLK. AFAIK there is also an FPGA mounted which > might affect the clock frequency as well. > > > Adding support for additional XVCLK frequencies isn't a huge task, but > > involves computing the internal PLL settings. My datasheet only gives > > settings for 24MHz, so it'd be back to the basic principles of PLL > > config to do it. > > Until things are more clear I would skip that for now as this module should be > running on a 24 MHz, I assume. I've measured the output of the oscillator on my Vision Components OV9281, and it is 24MHz. The oscillator is the square silver package on the back of my module by one of the screw holes. It is stamped U24 which would also indicate 24MHz. Holding the sensor with that silver component at the bottom edge, the clock output is the top right pin of the package. Unless yours is different for some reason, I'm out of ideas why you're seeing different frame rates. Dave
