[Libav-user] Request for Help - Error - h264_v4l2m2m @ 0x114ac00] Could not find a valid device

Adhuran Adhuran j.adhuran at surrey.ac.uk
Tue Oct 8 20:58:13 EEST 2019

Thank you very much.

Could you tell how I would be able to link x264 encoder for H264 and not v4l4m2m. To invoke x264 encoder with the source code.

Thanks in advance,

Kind Regards,


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From: Richard Hussong <rhussong at westpond.com>
Sent: Tuesday, October 8, 2019 6:46:26 PM
To: This list is about using libavcodec, libavformat, libavutil, libavdevice and libavfilter. <libav-user at ffmpeg.org>
Cc: Adhuran, Jayasingam (PG/R - Elec Electronic Eng) <j.adhuran at surrey.ac.uk>
Subject: Re: [Libav-user] Request for Help - Error - h264_v4l2m2m @ 0x114ac00] Could not find a valid device

You need a V4L2 video device to use that encoder. If you haven't already done this, run "ls -l /dev/video*", and make sure there is a video device and you have permission to write to it. If that doesn't help, you should raise the logging level of libav and see if it tells you what went wrong.

- Richard

On Tue, Oct 8, 2019 at 1:22 PM Adhuran Adhuran via Libav-user <libav-user at ffmpeg.org<mailto:libav-user at ffmpeg.org>> wrote:
Dear All,

I am trying to use ffmpeg source code top encode video streams in linux. I used the code provided in this link https://ffmpeg.org/doxygen/3.2/muxing_8c_source.html<https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fffmpeg.org%2Fdoxygen%2F3.2%2Fmuxing_8c_source.html&data=02%7C01%7Cj.adhuran%40surrey.ac.uk%7Cfeef03bf3fab4441db5208d74c17790f%7C6b902693107440aa9e21d89446a2ebb5%7C0%7C1%7C637061536017908633&sdata=DXwBLSqQMwhbyFnInOE%2F%2BYZ1TWzhIZhlNX2ZYKtG2rc%3D&reserved=0> to encode videos.

I got an error, when the code accessed the function ret = avcodec_open2<https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fffmpeg.org%2Fdoxygen%2F3.2%2Fgroup__lavc__core.html%23ga11f785a188d7d9df71621001465b0f1d&data=02%7C01%7Cj.adhuran%40surrey.ac.uk%7Cfeef03bf3fab4441db5208d74c17790f%7C6b902693107440aa9e21d89446a2ebb5%7C0%7C1%7C637061536017918630&sdata=hg0RqdJRa23310y5JSb8LXNAlfmbxtAKkSYSEh4iKVg%3D&reserved=0>(c, codec, &opt);

[h264_v4l2m2m @ 0x114ac00] Could not find a valid device
[h264_v4l2m2m @ 0x114ac00] can't configure encoder

May I know, why I get this error and how I could solve this?


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