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| Who | What | When |
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| *** | taliho has quit IRC (Quit: The Lounge - https://thelounge.chat) | [03:51] |
| ........................................................................................................... (idle for 8h52mn) | ||
| grohne | sailus: thinking more about V4L2_CID_STREAMING_TRIGGER_EXTERNAL, how bad would it be to allow a s_frame_interval with a zero denominator? | [12:43] |
| pinchartl | grohne: the issue with s_frame_interval is that it's an ill-defined API
most sensors don't have a concept of frame interval they have a pixel array sampling clock rate, and vertical and horizontal blanking which all together result in a given frame rate so there are multiple ways to achieve a given frame rate the use of that API is thus discouraged, in favour of exposing the individual parameters explicitly, except when the sensor exposes a frame rate natively | [12:54] |
| grohne | ok | [12:56] |
| pinchartl | (which is the case of some sensors containing an ISP, they expose the frame rate through a register and offer no way to control the clock rate and blankings individually)
and I expect external triggers to be mostly used with raw sensors | [12:57] |
| grohne | can you tell me what I was looking for instead? is that some CID?
V4L2_CID_VBLANK maybe? | [12:58] |
| pinchartl | V4L2_CID_HBLANK and V4L2_CID_VBLANK
and possibly V4L2_CID_LINK_FREQ if the driver supports changing the frequency | [12:59] |
| grohne | looking into them. thanks | [13:01] |
| so when targetting a particular frame rate, a user is supposed to retrieve the V4L2_CID_PIXEL_RATE, lookup the requested image dimensions w * h and determine values vblank, hblank within their respetive bounds such that (w + hblank) * (h + vblank) / pixel_rate becomes the desired frame interval?
is there any easier way to do this on the user side? | [13:10] | |
| pinchartl | that's correct
someone has to perform that calculation, and having it on the driver side would effectively remove flexibility from applications that need fine-grained control of the sensor that's why it's not considered to be the driver's responsibility | [13:19] |
| grohne | it kinda feels obvious in retrospect, but it wasn't. thank you. | [13:25] |
| is there some way to initiate a s_stream call from userspace on a subdev? | [13:30] | |
| pinchartl | no, that's always done through a video node | [13:31] |
| grohne | hmm. can I do one without a whole vb2? | [13:32] |
| pinchartl | do you mean without actually capturing to memory ? | [13:33] |
| grohne | yes
err without capturing memory | [13:33] |
| pinchartl | in theory yes. what kind of hardware do you have, where do the frames produced by the camera sensor go to ? | [13:34] |
| grohne | it's a custom board. the camer sensor feeds into another hardware before the data gets into the cpu | [13:35] |
| pinchartl | shouldn't you model the whole pipeline with V4L2 subdevs, until the DMA engine that captures frames to memory, which should then be modelled as a video node, using vb2 ? | [13:37] |
| grohne | in theory, yes. that's a huge task however. so the idea was to work on the camera sensor and bolt the rest together
I actually guess that the dma engine has a mainline driver, but switching over to it is not exactly trivial I've been working on getting this driver published for five years now. | [13:37] |
| pinchartl | it should be possible to hack something in the meantime, with a video node that doesn't actually perform capture | [13:39] |
| grohne | if you want the driver before the hardware is obsolete, I better hurry up :)
I actually do have a hacked up bolt-things-together-driver. it does the v4l2_async_notifier stuff to get the subdevs into /dev does that mean I need a struct video_device? | [13:39] |
| pinchartl | yes
but you can implement the bare minimum of the ioctls probably even just VIDIOC_S_STREAM | [13:44] |
| grohne | good that's up next then. thank you again
so I'll actually be able to test s_stream | [13:45] |
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| ezequielg | pinchartl: sailus: we never maanaged to merge the pixfmt to string helper?
I can't find it. I thought it was here already. | [15:36] |
| pinchartl | ezequielg: not sure, I haven't followed up | [15:37] |
| ezequielg | :'( | [15:38] |
| ..... (idle for 24mn) | ||
| here it is https://lore.kernel.org/linux-media/20190916115207.GO843@valkosipuli.retiisi.org.uk/t/#m1dda89afb049bad0065e7be9dd3242af6e2165af
still stalled? | [16:02] | |
| ...... (idle for 26mn) | ||
| sailus: need help with those, i might be able to squeeze them if it's not a lot of work. | [16:28] | |
| sailus | ezequielg: Uh-oh. | [16:30] |
| ezequielg | did I open pandora's box? | [16:30] |
| sailus | There were patches, but I don't quite remember where it ended up to.
Let me find them. | [16:30] |
| It seems to have stalled in my inbox, yes.
Sorry about that. Here: https://lore.kernel.org/linux-media/20200427145303.29943-1-sakari.ailus@linux.intel.com/ | [16:40] | |
| I think it actually should be close to merging.
Lots of small things to fix still. No wonder that something else took over this in priority. :-P | [16:48] | |
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| formruga | Hi. I would like to ask how to check if v4l2 m2m kernel driver is compilant with specification. I'm focused on "dynamic resolution change" as stated in https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/dev-decoder.html#dynamic-resolution-change.
I would like to check if decoder is capable to play crowd_run_1080X512_fr30_bd8_frm_resize_l3.webm stream playback from VP9 test suite. This stream uses frame resize feature, which changes resolution of decoded frames twice a second (https://www.webmproject.org/vp9/levels/). I try to check the stream on Odroid N2 with Armbian Buster with 5.8.16 mainline kernel. I am trying to play with V4L2 GStreamer element and some abandoned patches. I see that the code is able to subscribe proper event and detect source resolution change. I also see expected "last buffer"/EPIPE behaviour, but I have a problem with streaming resuming. I think that maybe I should look into v4l2-compliance, but it seems that I can't use it. or maybe I don't know how to use it | [17:19] |
| .... (idle for 16mn) | ||
| BTW. I tried to search logs of this channels on https://linuxtv.org/irc/irclogger_log_search/v4l?search=VP9&action=search&error=0, but I got the error "*** ERROR: agrep not found!***" | [17:39] | |
| ezequielg | sailus: ah, right. Last time I looked I wasn't a fan of that solution, but I'm probably wrong since it's the one that gained more traction. | [17:53] |
| sailus | ezequielg: Not my first choice either, no, but it seems people like it.
And having a way to do that is really nice. Although I have to admit that this way the end result can be move verbose and flexible than the one based on format specifier macros. | [17:56] |
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| *** | kaairagupta has quit IRC (*.net *.split)
kbingham[m] has quit IRC (*.net *.split) epaul1 has quit IRC (*.net *.split) ric96 has quit IRC (*.net *.split) koike1 is now known as koike | [20:38] |
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| ezequielg | sailus: yes, I guess something is better than nothing and each driver does its own thing. the v3 is from April, do you plan to revive it ? :-) | [21:02] |
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| sailus | ezequielg: I'm a little busy right now but I factored in the comments I got, need to test the end result still.
I pushed it to fourcc branc in my linuxtv.org tree if you want to play with it. There are no guarantees. | [21:34] |
| ........ (idle for 35mn) | ||
| *** | fling has quit IRC (Ping timeout: 272 seconds) | [22:10] |
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