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v4l2rtspserver stops streaming when grabbing a still from the same video device (using v4l2loopback and v4l2copy) #318

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dragulesq opened this issue Jun 20, 2023 · 2 comments
Open

v4l2rtspserver stops streaming when grabbing a still from the same video device (using v4l2loopback and v4l2copy) #318

dragulesq opened this issue Jun 20, 2023 · 2 comments

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@dragulesq
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Hello and thanks for your wonderful software.
I've been using for a few years now with several raspi zeroes and it's been solid.

Yesterday, I ran into an issue where v4l2rtspserver stops streaming to already connected clients as well as new connections. VLC and ffplay both report timeouts. This happens when I try to use ffmpeg to capture one still frame from the same video device that v4l2rtspserver is using.

I am using v4l2loopback and v4l2copy from /dev/video0 to /dev/video2 as I would like to have two consumers of /dev/video2: v4l2rtspserver always and ffmpeg occasionally. I am running this on a bit of an exotic hardware as a proof of concept, Seagate Dockstar with an old Logitech C900 USB Camera that supports MJPG natively.

$ uname -a
Linux tv2 6.0.7-kirkwood-tld-1 #1.0 PREEMPT Fri Nov 4 15:08:17 PDT 2022 armv5tel GNU/Linux

$ dmesg | grep usb | grep UVC
[   25.966606] usb 1-1.3: Found UVC 1.00 device <unnamed> (046d:0990)
[   26.065923] input: UVC Camera (046d:0990) as /devices/platform/ocp@f1000000/f1050000.ehci/usb1/1-1/1-1.3/1-1.3:1.0/input/input0

$ v4l2-ctl --list-formats -d 0 /dev/video0
ioctl: VIDIOC_ENUM_FMT
        Type: Video Capture

        [0]: 'MJPG' (Motion-JPEG, compressed)
        [1]: 'YUYV' (YUYV 4:2:2)

Here is my software setup:

$ sudo modprobe v4l2loopback video_nr=2
$ v4l2-ctl -d /dev/video0 --set-fmt-video=width=960,height=720,pixelformat=MJPG --set-parm=10
$ nohup v4l2copy /dev/video0 /dev/video2 &> v4l2copy.log &
$ nohup v4l2rtspserver -fMJPG -F 10 -W 960 -H 720 /dev/video2,0 &> v4l2rtspserver.log &

Here is the ffmpeg command I use to grab a still frame from /dev/video2 :

ffmpeg -v 32 -hide_banner -f video4linux2 -input_format mjpeg -i /dev/video2 -vframes 1 output%3d.jpg
Input #0, video4linux2,v4l2, from '/dev/video2':
  Duration: N/A, start: 356418.543514, bitrate: N/A
  Stream #0:0: Video: mjpeg (Baseline), yuvj422p(pc, bt470bg/unknown/unknown), 960x720, 10 fps, 10 tbr, 1000k tbn
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> mjpeg (native))
Press [q] to stop, [?] for help
Output #0, image2, to 'output%3d.jpg':
  Metadata:
    encoder         : Lavf60.3.100
  Stream #0:0: Video: mjpeg, yuvj422p(pc, bt470bg/unknown/unknown, progressive), 960x720, q=2-31, 200 kb/s, 10 fps, 10 tbn
    Metadata:
      encoder         : Lavc60.3.100 mjpeg
    Side data:
      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: N/A
frame=    1 fps=0.0 q=5.7 Lsize=N/A time=00:00:00.00 bitrate=N/A speed=   0x
video:45kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

Here is the v4lrtspserver verbose output, there is the client connecting in the middle and then the error at the end:

$ v4l2rtspserver -vv -fMJPG -F 10 -W 960 -H 720 /dev/video2 &> v4l2rtspserver.log &
[NOTICE] /home/username/v4l2rtspserver/main.cpp:269
        Version: 0.3.7-19-g9029be3 live555 version:2022.10.01
[NOTICE] /home/username/v4l2rtspserver/src/V4l2RTSPServer.cpp:37
        Create V4L2 Source.../dev/video2
[NOTICE] /home/username/v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:133
        driver:v4l2 loopback capabilities:85200003 mandatory:4000001
[NOTICE] /home/username/v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:135
        /dev/video2 support output
[NOTICE] /home/username/v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:136
        /dev/video2 support capture
[NOTICE] /home/username/v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:138
        /dev/video2 support read/write
[NOTICE] /home/username/v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:139
        /dev/video2 support streaming
[DEBUG] /home/username/v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:71
        /dev/video2:MJPG size:960x720 bufferSize:2764800
[NOTICE] /home/username/v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:225
        /dev/video2:MJPG size:960x720 bufferSize:2764800
[DEBUG] /home/username/v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:71
        /dev/video2:MJPG size:960x720 bufferSize:2764800
[NOTICE] /home/username/v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:246
        fps:1/10
[NOTICE] /home/username/v4l2rtspserver/libv4l2cpp/src/V4l2Device.cpp:247
        nbBuffer:2
[NOTICE] /home/username/v4l2rtspserver/libv4l2cpp/src/V4l2MmapDevice.cpp:49
        Device /dev/video2
[NOTICE] /home/username/v4l2rtspserver/libv4l2cpp/src/V4l2MmapDevice.cpp:73
        Device /dev/video2 nb buffer:2
[INFO] /home/username/v4l2rtspserver/libv4l2cpp/src/V4l2MmapDevice.cpp:92
        Device /dev/video2 buffer idx:0 size:2764800 offset:0
[INFO] /home/username/v4l2rtspserver/libv4l2cpp/src/V4l2MmapDevice.cpp:92
        Device /dev/video2 buffer idx:1 size:2764800 offset:0
[NOTICE] /home/username/v4l2rtspserver/src/V4l2RTSPServer.cpp:62
        Create Source .../dev/video2
[NOTICE] /home/username/v4l2rtspserver/inc/BaseServerMediaSubsession.h:49
        format:video/JPEG
[NOTICE] /home/username/v4l2rtspserver/inc/V4l2RTSPServer.h:237
        Play this stream using the URL "rtsp://10.1.1.7:8554/unicast"
[NOTICE] /home/username/v4l2rtspserver/src/V4L2DeviceSource.cpp:96
        begin thread
[DEBUG] /home/username/v4l2rtspserver/src/V4L2DeviceSource.cpp:108
        waitingFrame    delay:1ms

...

[DhandleCmd_SETUP:SETUP rtsp://10.1.1.7:8554/unicast/track1 RTSP/1.0
CSeq: 4
User-Agent: LibVLC/3.0.18 (LIVE555 Streaming Media v2016.11.28)
Transport: RTP/AVP;unicast;client_port=52268-52269

...

[DEBUG] /home/username/v4l2rtspserver/src/V4L2DeviceSource.cpp:143
        Queue is empty
[DEBUG] /home/username/v4l2rtspserver/src/V4L2DeviceSource.cpp:108
        waitingFrame    delay:100ms
[DEBUG] /home/username/v4l2rtspserver/src/V4L2DeviceSource.cpp:224
        postFrame       timestamp:1687302032.125536     size:63228      diff:0ms
[DEBUG] /home/username/v4l2rtspserver/src/V4L2DeviceSource.cpp:257
        queueFrame      timestamp:1687302032.125536     size:63228      diff:0ms
[DEBUG] /home/username/v4l2rtspserver/src/V4L2DeviceSource.cpp:165
        deliverFrame    timestamp:1687302032.128871     size:63228      diff:3ms        queue:0
[DEBUG] /home/username/v4l2rtspserver/src/MJPEGVideoSource.cpp:49
        DQT length:67
[DEBUG] /home/username/v4l2rtspserver/src/MJPEGVideoSource.cpp:57
        Quantization table idx:0 precision:0 size:64 total size:128
[DEBUG] /home/username/v4l2rtspserver/src/MJPEGVideoSource.cpp:49
        DQT length:67
[DEBUG] /home/username/v4l2rtspserver/src/MJPEGVideoSource.cpp:57
        Quantization table idx:1 precision:0 size:64 total size:128
[DEBUG] /home/username/v4l2rtspserver/src/MJPEGVideoSource.cpp:26
        SOF length:17
[INFO] /home/username/v4l2rtspserver/src/MJPEGVideoSource.cpp:42
        width:960 height:720 type:0 precision:8
[DEBUG] /home/username/v4l2rtspserver/src/MJPEGVideoSource.cpp:77
        SOS length:12
[DEBUG] /home/username/v4l2rtspserver/src/MJPEGVideoSource.cpp:87
        headerSize:208
[DEBUG] /home/username/v4l2rtspserver/src/V4L2DeviceSource.cpp:143
        Queue is empty
[DEBUG] /home/username/v4l2rtspserver/src/V4L2DeviceSource.cpp:108
        waitingFrame    delay:100ms
[DEBUG] /home/username/v4l2rtspserver/src/V4L2DeviceSource.cpp:224
        postFrame       timestamp:1687302032.225471     size:63291      diff:0ms
[DEBUG] /home/username/v4l2rtspserver/src/V4L2DeviceSource.cpp:257
        queueFrame      timestamp:1687302032.225471     size:63291      diff:0ms
[DEBUG] /home/username/v4l2rtspserver/src/V4L2DeviceSource.cpp:165
        deliverFrame    timestamp:1687302032.231454     size:63291      diff:5ms        queue:0
[DEBUG] /home/username/v4l2rtspserver/src/MJPEGVideoSource.cpp:49
        DQT length:67
[DEBUG] /home/username/v4l2rtspserver/src/MJPEGVideoSource.cpp:57
        Quantization table idx:0 precision:0 size:64 tVIDIOC_DQBUF: Invalid argument

An important note: running the ffmpeg command doesn't always produce this error. It seems that it is a timing issue. Sometimes I have to run it a few times before it triggers the error, sometimes just once. When the error occurs I have to restart v4l2rtspserver as new client connections report timeouts. New client connections are reported in the v4l2rtspserver log but the clients report timeouts and no video streams are displayed.

Please advise and let me know if you need any more debug information.
@dragulesq dragulesq changed the title v4l2rtspserver server stops streaming when grabbing a still from the same video device (using v4l2loopback and v4l2copy) v4l2rtspserver stops streaming when grabbing a still from the same video device (using v4l2loopback and v4l2copy) Jun 20, 2023
@dragulesq
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@mpromonet any thoughts on this? any ideas on what I could try differently? Thanks!

@mpromonet
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Hi,

the error VIDIOC_DQBUF: Invalid argument seems to indicate the v4l2 device doesnot give more frame. You may look to v4l2loopback, may be upgrading it.

Best Regards,
Michel.

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@mpromonet @dragulesq