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

Richard Hussong rhussong at westpond.com
Sat Oct 12 00:37:37 EEST 2019

I think you want the "libx264" encoder. To use it, you need to install
libx264, and your libav libraries need to have been built with the
"enable-libx264" flag. It is enabled by default in most distributions, I
think. The libx264 encoder has a lot of options; you should probably just
pick one of its presets and use that. The accepted answer to this old post
shows how you can do that using av_dict_set():

- Richard

On Tue, Oct 8, 2019 at 1:58 PM Adhuran Adhuran <j.adhuran at surrey.ac.uk>

> 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,
> Adhuran
> Sent from my Samsung Galaxy S9 - Powered by Three
> Get Outlook for Android <https://aka.ms/ghei36>
> ------------------------------
> *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> 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?
>> Regards,
>> Adhuran.
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