Should I upgrade?

Eric Katzfey

@Ed-Sutter Yes, use the uvc-generic record as a template. You can modify resolution, bit rate, etc. to match what you are putting into the pipe from voxl-uvc-server.

Ed Sutter

@Eric-Katzfey Ok, after running opkg update/opkg upgrade I see there now is a uvc-generic entry (that wasn't there prior to the upgrade).

I'm still having trouble though. Here's what I'm doing sequentially:

Plug in my camera and get the VID/PID.
Run voxl-uvc-server -v MYVID -p MYPID -r640x480.
Run voxl-streamer -c uvc-generic.

The first time I ran this voxl-streamer responded with:

Using configuration uvc-generic
Using configuration file /etc/modalai/voxl-streamer.conf
Camera server Connected
ERROR: Frame size mismatch 613388 614400
ERROR: Timeout on input parameter initialization

and eventually voxl-uvc-server crashed (Segmentation fault).

Then, strangely, I tried it a second time (changed nothing) and things were somewhat better. Voxl-streamer responded with:

Using configuration uvc-generic
Using configuration file /etc/modalai/voxl-streamer.conf
Camera server Connected
Stream available at rtsp://127.0.0.1:8900/live

and with that I was able to run VLC on my host to see some [not-so-good] video. The frames were breaking up like they were out of sync.

I used ctrl-c to terminate voxl-streamer, and shortly after that voxl-uvc-server crashed again.

Any clue what might be going on? Are there other pages I should be reading besides voxl-uvc-server and voxl-streamer?

Eric Katzfey

@Ed-Sutter Try adding the debug options when launching both voxl-uvc-server and voxl-streamer and then share the output. What camera are you using?

Ed Sutter

@Eric-Katzfey With -d on voxl-uvc-server, and voxl-streamer active, I see this output...

write to ch: 0 id: 0 result: 614400 errno: 0
previous client state was 2
write to ch: 0 id: 0 result: 40 errno: 0
previous client state was 2
write to ch: 0 id: 0 result: 613388 errno: 0
previous client state was 2
write to ch: 0 id: 0 result: 40 errno: 0
previous client state was 2
write to ch: 0 id: 0 result: 614400 errno: 0
previous client state was 2
write to ch: 0 id: 0 result: 40 errno: 0
previous client state was 2
write to ch: 0 id: 0 result: 613388 errno: 0
previous client state was 2
write to ch: 0 id: 0 result: 40 errno: 0
previous client state was 2
write to ch: 0 id: 0 result: 612364 errno: 0
previous client state was 2
write to ch: 0 id: 0 result: 40 errno: 0
previous client state was 2
write to ch: 0 id: 0 result: 611364 errno: 0
previous client state was 2
write to ch: 0 id: 0 result: 40 errno: 0
previous client state was 2
write to ch: 0 id: 0 result: 610328 errno: 0

At 640x480 a consistent frame size would be 614400, so this is likely the cause of the frame breakup that I see visually.
My camera is a Microsoft 1080P HD Sensor, that can emit YUY2, M420 or MJPG format.

Eric Katzfey

@Ed-Sutter Can you share all of the output from both applications? We have never tried that camera. The supported format would be YUY2 but that should result in a fixed size frame. Not sure why it is moving around like that.

Ed Sutter

@Eric-Katzfey Sure... I just ran it again, and didn't even get to run VLC on my host and the server crashed. Here are the outputs...
voxl-uvc_server:

/ # voxl-uvc-server -v045e -p0772 -r640x480 -d
Enabling debug messages
voxl-uvc-server starting
Vendor ID 0x045e chosen
Product ID 0x0772 chosen
Image resolution 640x480, 30 fps chosen
UVC initialized
Device 045e:0772 found
Device opened
uvc_get_stream_ctrl_format_size succeeded for format 0
Streaming starting
Got frame callback! frame_format = 3, width = 640, height = 480, length = 613388, ptr = (nil)
 * got image 30
 * got image 60
 * got image 90
 * got image 120
 * got image 150
 * got image 180
 * got image 210
 * got image 240
 * got image 270
 * got image 300
 * got image 330
 * got image 360
 * got image 390
 * got image 420
 * got image 450
 * got image 480
 * got image 510
 * got image 540
 * got image 570
 * got image 600
Segmentation fault
/ #

voxl-streamer:

/ # voxl-streamer -c uvc-generic -d
Using configuration uvc-generic
Enabling debug messages
Using configuration file /etc/modalai/voxl-streamer.conf
MPA interface chosen
Input pipe name /run/mpa/uvc/
Output stream width 640
Output stream height 480
Output stream bitrate 1000000
Output stream rotation 0
Output frame decimator 1
No image overlay specified
Camera server Connected
First frame timestamp: 5791926161024
Second frame timestamp: 5791958239848
Calculated frame delta in ns: 32078824
Calculated frame delta in 100us: 320
Calculated input frame rate is: 31
Output frame rate will be: 31
Meta data from incoming frame:
        magic_number 0x564F584C
        timestamp_ns: 5791958239848
        frame_id: 519
        width: 640
        height: 480
        size_bytes: 614400
        stride: 1280
        exposure_ns: 100
        gain: 100
        format: 8
Input parameters initialized
Made rtsp_server
Created RTSP server main loop context
Created RTSP server main loop
Created RTSP server main loop source for callback
Got 2 from gst_rtsp_server_attach
Stream available at rtsp://127.0.0.1:8900/live
Camera server Disconnected
ERROR in pipe_client_init_channel opening request pipe: No such device or address
Most likely the server stopped without cleaning up
Client is cleaning up pipes for the server

^CGot SIGINT, exiting
Trying to stop loop
g_main_loop exited
voxl-streamer ending
/ #

You can see in the voxl-streamer output that it was running till voxl-uvc-server crashed. Eventually, I used Ctrl-C to terminate voxl-streamer.
If you want me to try anything, just let me know. I've worked with several USB cameras myself but primarily with V4L2/OpenCV/Gstreamer. I haven't used LibUVC, can't find much documentation. Can you point me to the libuvc source?

Eric Katzfey

@Ed-Sutter We use our own version of libuvc. You can find our project here: https://gitlab.com/voxl-public/voxl-sdk/third-party/voxl-libuvc

Eric Katzfey

@Ed-Sutter I think the problem is the varying frame size. That's probably causing a problem somewhere (either memory leak or overflow).

Ed Sutter

@Eric-Katzfey I agree, but I don't understand why the frame size varies! Its not compressed, so it should be a fixed size per frame. Know what I mean?

Eric Katzfey

@Ed-Sutter Yes. But maybe just a quirk of the camera. There are a few ways to go about fixing this. It looks like the frames are either the correct size or smaller. If that's the case, you could always add "fake" data to the end of the received buffer to make it the correct size in voxl-uvc-server and then write it into the pipe. You could try this and see if that makes the stream work.

Ed Sutter

@Eric-Katzfey Ok, I'll dig into this more. I need to understand it anyway, so I'll look at libuvc and voxl-uvc-server and let you know what I figure out.

Eric Katzfey

@Ed-Sutter Excellent, thanks!

Ed Sutter

@Eric-Katzfey FYI... Using a Logitech BRIO camera seems to work fine... the frame size always returns the same value (614400 in my case). Still, I wanna spend some time attempting to figure out why the Microsoft HD camera doesn't work as well...

Eric Katzfey

@Ed-Sutter We have tested with these cameras:

Logitech C270
Logitech C930e
Logitech Brio (USB 2.0 and USB 3.0 on VOXL 2)
Videology 5MP Micro USB 2.0 Board Camera
PureThermal Mini with Flir Lepton
Flir Boson 640
Blue Robotics h264 camera

Ed Sutter

@Eric-Katzfey By the way, regarding "upgrading"... All I did was opkg update; opkg upgrade. I really don't know what all that updated (aside from /etc/modalai/voxl-streamer.conf); but the output of "voxl-version" didn't change at all.
Based on that it appears I'm running with a system-image that was built on 2021-06-06 (about 15 months ago). Is that the most recent?

Eric Katzfey

@Ed-Sutter We are preparing a new VOXL platform release but are still completing an update of our ToF camera support. Once that is complete the release will go out.

Ed Sutter

@Eric-Katzfey Ok, no rush (just curious)... Is that updated by the same procedure (opkg update; opkg upgrade)?

Eric Katzfey

@Ed-Sutter No, there is a bash script to handle it. The opkg method is good for SDK and package updates but the full platform release also contains a new system image that needs to be flashed via fastboot.

Ed Sutter

@Eric-Katzfey Update regarding the intermittent frame size when using the MS-1080P-HD camera... I pulled down the latest libuvc code from github and built it on my Ubuntu 18.04 machine. I was then able to run uvc_test on that camera and it always came back with the same (correct) frame size.
Is there any chance that the libuvc version you guys have on voxl-public is a bit out-of-date?

Ed Sutter

@Eric-Katzfey Just to gather a little more data, I took the voxl-libuvc code and built it on Ubuntu18.04. Then I ran uvc_test with the MS-1080P-HD camera and it worked fine.

To do this I cloned libuvc and voxl-libuvc, then prior to building libuvc, I copied all the source files (*.[ch]) from voxl-libuvc to libuvc. This allowed me to use voxl-libuvc source code, but still build on a native ubuntu host.

Anyway, that eliminates voxl-libuvc from the suspect list. Since voxl-uvc-server's callback is fed the frame size, that kinda points to the driver as a possible suspect.

Any thoughts?

If interested, I can post the script I used to do that build.