Issues Using GStreamer with v4l2 Elements

Mon Aug 22 17:09:14 UTC 2022

Hi Joshua,

Le lundi 22 août 2022 à 10:58 -0400, Joshua Quesenberry a écrit :
> Nicolas,
> 
> Please find attached zip files for a jpeg capture and a raw capture.

>From a quick look, my impression is that the driver does delay the end of the
draining flow (CMD_STOP or bytesused = 0) to after the last decoded buffer has
been dequeued. From your trace, you can observe this by a chain from the
identity_pre and not for the identify_post.

I believe this is an issue that was previously reported to RPi maintainers and
should in theory be known or addressed.

regards,
Nicolas

> 
> Thanks!
> 
> Josh Q
> 
> -----Original Message-----
> From: Nicolas Dufresne <nicolas at ndufresne.ca> 
> Sent: Monday, August 22, 2022 9:34 AM
> To: Joshua Quesenberry <engnfrc at gmail.com>
> Cc: 'Discussion of the development of and with GStreamer' <gstreamer-devel at lists.freedesktop.org>
> Subject: Re: Issues Using GStreamer with v4l2 Elements
> 
> Le lundi 22 août 2022 à 09:13 -0400, Joshua Quesenberry a écrit :
> > Is anyone able to assist me with overcoming this issue? I’m currently 
> > unable to use a particular make/model of camera (ELP-USBFHD01M w/ 
> > OV2710) with the v4l2jpegdec element. I’ve had other cameras work with 
> > it. I don’t notice any errors when upping the GST_DEBUG options. 
> > Traffic is at the input pad of the element, but nothing coming from 
> > the output pad. I have some logs posted on the RPi forum issue I posted:
> > https://forums.raspberrypi.com/viewtopic.php?p=2031632#p2031632
> 
> Perhaps you should still share the pipeline (in gst-launch syntax) that you are trying to use ? As you don't see any errors, perhaps you should store to disk a snippet of JPEG and share that too ? As it is now, I don't see much I can add to help you.
> 
> >  
> > Thanks,
> >  
> > Josh Q
> >  
> > From: Joshua Quesenberry <engnfrc at gmail.com>
> > Sent: Sunday, August 14, 2022 9:00 AM
> > To: Nicolas Dufresne <nicolas at ndufresne.ca>
> > Cc: Discussion of the development of and with GStreamer 
> > <gstreamer-devel at lists.freedesktop.org>; Joshua Quesenberry 
> > <EngnFrc at gmail.com>
> > Subject: Re: Issues Using GStreamer with v4l2 Elements
> >  
> > I’m coming back to this finally. I’ve yet to find a solution to 
> > v4l2jpegdec not working with this specific make/model camera. It works fine with jpegdec.
> > With v4l2jpegdec there’s no downstream data, observable using identity 
> > element, but I do see data upstream using identity. I’m not seeing any 
> > errors in dmesg or in the gstreamer output if I up the debug levels. 
> > What else can be done to try and figure out why things aren’t working?
> >  
> > Thanks,
> >  
> > Josh Q
> >  
> > On Fri, May 13, 2022 at 4:46 PM Nicolas Dufresne <nicolas at ndufresne.ca> wrote:
> > > Le vendredi 13 mai 2022 à 14:28 -0400, Joshua Quesenberry a écrit :
> > > > That seems very confusingly labeled, am I missing something in the 
> > > > below high-level description? From an element's perspective, I 
> > > > wouldn't expect to be outputting to my sink pad (upstream) or 
> > > > capturing from my src pad (downstream).
> > > > 
> > > > Src element -> v4l2 sink using output-io-mode ... v4l2 src using 
> > > > capture- io-mode -> Sink element
> > > > 
> > > > In this example, should the elements dmabuf-import be on the 
> > > > upstream or downstream side? Likewise with the dmabuf? I'm not 
> > > > certain if A) the downstream is creating the dmabuf and the 
> > > > upstream is importing it to dump to or B) the upstream is creating 
> > > > the dmabuf and the downstream is importing it for use... it seems 
> > > > like maybe both work when I try?
> > > 
> > > I don't see a pipeline description I could comment on. By default, 
> > > all v4l2 srcpad are dmabuf exporters. But the sink pad are not 
> > > automatically importer, as this code is experimental and need some 
> > > polishing and testing.
> > > 
> > > > 
> > > > Thanks!
> > > > 
> > > > JQ
> > > > 
> > > > -----Original Message-----
> > > > From: Nicolas Dufresne <nicolas at ndufresne.ca>
> > > > Sent: Friday, May 13, 2022 8:47 AM
> > > > To: Joshua Quesenberry <engnfrc at gmail.com>
> > > > Cc: Discussion of the development of and with GStreamer 
> > > > <gstreamer-devel at lists.freedesktop.org>
> > > > Subject: Re: Issues Using GStreamer with v4l2 Elements
> > > > 
> > > > Le vendredi 13 mai 2022 à 00:52 -0400, Joshua Quesenberry a écrit :
> > > > > Hi Nicolas,
> > > > > 
> > > > > Sorry for the late reply, I got covered up with other stuff and 
> > > > > am just getting a minute to come back to this.
> > > > > 
> > > > > > Just read your post, looks like you are asking about at least 
> > > > > > two distinct issue. In one case, v4l2jpegdec does not work at 
> > > > > > all for you. There isn't much information, have you 
> > > > > > considering prepending jpegparse in front of it ? That may 
> > > > > > help ? Jpeg V4L2 decoder is probably one of the least tested decoder in the v4l2 lot.
> > > > > 
> > > > > Correct, two separate issues I'm running into.
> > > > > 
> > > > > v4l2jpegdec works fine with one camera, but not the other. I'm 
> > > > > setting them both up very similarly, so it escapes me what could 
> > > > > be different to cause this behavior. I just tried jpegparse in 
> > > > > the pipeline just before v4l2jpegdec and that didn't have any 
> > > > > effect, still the identity just after the decode is never 
> > > > > printed. I also tried dropping down from 1280x720 at 60fps to 
> > > > > 1024x768 at 30fps to lessen the load a bit and that had no effect either.
> > > > > 
> > > > > > In the second issue, it works, but its slow. Could it be that 
> > > > > > you are loading the CPU ? v4l2h264enc does not automatically 
> > > > > > do zero-copy. You can experimentally enable it passing 
> > > > > > output-io- mode=dmabuf-import.
> > > > > 
> > > > > I suppose it could be GPU load? When I've looked for ways to 
> > > > > measure what the GPU is doing, I've unfortunately not found much 
> > > > > of significance. The CPU load is quite low during this testing, 
> > > > > <10% for the gstreamer pipeline according to htop. I have a 
> > > > > pipeline already with the output-io-modes set to dmabuf-import, 
> > > > > but before my original post I switched everything back to auto 
> > > > > in hopes things may start working appropriately, however that 
> > > > > was not the case. Keep in mind that I have an identity in 
> > > > > between the source caps and the capssetter, this is where I see 
> > > > > the average framerate drop with v4l2h264enc present.
> > > > > 
> > > > > I've found that by adding more queues to the pipeline and then 
> > > > > setting all queues to have a leaky downstream that the average 
> > > > > rate at the source has now climbed back up to what I expected 
> > > > > all along, so I'm assuming the issue is a clogged up downstream 
> > > > > affecting the upstream as far as the source? After these changes 
> > > > > input rate is ~30fps and output to file ~15fps, which is what 
> > > > > I'm asking for, and the CPU usage is around ~30%. Playing around 
> > > > > with the dmabuf-import option it appears I'm able to get similar 
> > > > > rates with a drop in CPU usage to around ~10%, very exciting!
> > > > > 
> > > > > How do the v4l2 elements work with queues? What do they do when 
> > > > > stuck in between a dmabuf-import src pad and dmabuf sink pad? 
> > > > > They don't have io-modes to be specified (at least at the user 
> > > > > level) and I don't see a v4l2queue or something of the like. 
> > > > > Tomorrow I'll do some more experiments to see which queues that I've added are unnecessary.
> > > > 
> > > > M2M elements have two queues, so you have output-io-mode (the sink 
> > > > pad) and capture-io-mode (for the src pad).
> > > > 
> > > > > 
> > > > > So now, camera #1 not getting through v4l2jpegdec is my major 
> > > > > roadblock. Anyone have ideas on how to debug this one or know 
> > > > > what could cause this behavior?
> > > > > 
> > > > > FYI, I did dump additional information to the RPi Forums 
> > > > > question a few days ago, if something else is needed, just let me know.
> > > > > 
> > > > > Thanks!
> > > > > 
> > > > > JQ
> > > > > 
> > > > > On Mon, May 9, 2022 at 4:15 PM Nicolas Dufresne 
> > > > > <nicolas at ndufresne.ca>
> > > > > wrote:
> > > > > > 
> > > > > > Le lundi 09 mai 2022 à 12:04 -0400, Joshua Quesenberry via 
> > > > > > gstreamer-devel a écrit :
> > > > > > > Hey Everyone!
> > > > > > > 
> > > > > > > I’m having some trouble using the v4l2 elements on an RPi. 
> > > > > > > I’ve posted a detailed summary on the Raspberry Pi forum. 
> > > > > > > Can anyone lend a hand? I’m not sure how many of you are 
> > > > > > > frequent users of the RPi, so figured I’d reach out here in 
> > > > > > > parallel in case the RPi forum isn’t the right audience.
> > > > > > > https://forums.raspberrypi.com/viewtopic.php?t=334215
> > > > > > 
> > > > > > Just read your post, looks like you are asking about at least 
> > > > > > two distinct issue. In one case, v4l2jpegdec does not work at 
> > > > > > all for you. There isn't much information, have you 
> > > > > > considering prepending jpegparse in front of it ? That may 
> > > > > > help ? Jpeg V4L2 decoder is probably one of the least tested decoder in the v4l2 lot.
> > > > > > 
> > > > > > In the second issue, it works, but its slow. Could it be that 
> > > > > > you are loading the CPU ? v4l2h264enc does not automatically 
> > > > > > do zero-copy. You can experimentally enable it passing 
> > > > > > output-io- mode=dmabuf-import.
> > > > > > 
> > > > > > Nicolas
> > > > > > 
> > > > > > > 
> > > > > > > Thanks,
> > > > > > > 
> > > > > > > JQ
> > > > > > > 
> > > > > > > 
> > > > > > 
> > > > 
> > > > 
> 