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mpromonet / webrtc-streamer

WebRTC streamer for V4L2 capture devices, RTSP sources and Screen Capture
https://webrtcstreamer.agreeabletree-365b9a90.canadacentral.azurecontainerapps.io/?layout=2x2
The Unlicense
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How to get correct m_videoaudiomap for v4l2 devices when two devices with the same 'PRODUCT' plugged in? #603

Closed rouxianmantou closed 1 year ago

rouxianmantou commented 1 year ago

Describe the bug 1st: I use Ubuntu with two HDMI-USB capture card(v4l2 device, same brand and model) plugged in. 2nd: When connecting to the stream, the video and audio may not match.

To Reproduce same with [Describe the bug]

What happens Firstly, one Linux with two HDMI-USB capture card(v4l2 device, same brand and model) plugged in. From the code(as shown in the Screenshots), I found in PeerConnectionManager.cpp#m_videoaudiomap stores the map of video and audio of v4l2 devices.

Then in the function 'V4l2AlsaMap.h#std::map<std::string,std::string> getV4l2AlsaMap()', it exec 'getVideoDevices()' and 'getAudioDevices()', we can get 'VideoDeviceMap<videoDevName, devId>' and 'AudioDeviceMap<devId, audioDevName>'. And then, in 'V4l2AlsaMap.h#std::string getDeviceId(const std::string& evt)', the video and audio is group by 'PRODUCT' or 'PCI_SUBSYS_ID' in 'device/uevent'. But when two devices has same 'PRODUCT', the video and audio may not match.

I don't know match about Linux. Is there any way to avoid the situation, maybe use other info to group video and audio?

Screenshots image image image image image

Desktop (please complete the following information):

rouxianmantou commented 1 year ago

Hello mpromonet,

I plan to use the realpath of the symlink of device(/sys/class/video4linux(sound)/device), it can be x-y:m.n(video: 3-1:1.0 audio: 3-1:1.2, usb port), add x-y to the deviceId, I think the video and audio should match when x-y(both 3-1) is the same. emmm I will do this for now, hope no bugs.

If you have some idea, pls help to tell me, thanks a lot!

rouxianmantou commented 1 year ago

Hello @mpromonet another related question QAQ the m_videoaudiomap is from devices in /sys/class/video4linux(sound) when call /api/getMediaList api, it will find audio device with the devname from webrtc api, it could not match, I think?

mpromonet commented 1 year ago

Hi @rouxianmantou

You are right, in the past device name was used, but as it is not unique, I change my mind and use device number. This part of the code need to be adapt to the new behavior.

Best Regards, Michel.

rouxianmantou commented 12 months ago

Thanks a lot!