Hello everyone,
I'm trying to use custom ffmpeg commands through ffmpegformats.xml in recording from a Magewell capture card. It works properly when recording through vmix interface, thus invoking the ffmpeg.exe in vmix installation folder. What about if I wanted to pass the input source (as seen by vMix) to an independent build of ffmpeg in my PC? In particular I would like to exploit the .asf streams created by vMix/ffmpeg i.e. input type



and put the pipe as a source in an independent ffmpeg CLI. What I really want is to avoid the dshow call in my ffmpeg command, due to an issue in recognizing full audio features of my Magewell card as DirectShow audio device.

As you can expect, the input pipe as it is reported in vMix/ffmpeg log file cannot be used after ending the record.
Is there any (hopefully simple...) way to grab the key produced by vMix in the pipe and use it real time in a totally separate ffmpeg command?

Thank you!

I have already explained this with many details in this thread:
https://forums.vmix.com/....aspx?g=posts&t=8659

PS : Remember GTX cards only accepts 2 simultaneous encodes. Might need to adapt your script in order to use CPU encoding instead of GPU.

Maybe I wasn't clear enough...

You can do what I wrote AT THE SAME TIME as vMix records or streams... I use this method to simultaneously stream or record to other destinations or codecs.
I only mentionned the log file as an easy way to get a working sample for commandlines which most people are not familiar with. I suggested to do a small record or stream in order to create a log file with appropriate settings/presets.


Or FFMPEG, or VLC or OBS or any other application which accepts audio and video capture (virtual) devices...


I'd be curious to know why


The way I indicated which is not to try to intercept the pipe but rather use EXT or EXT2 virtual devices


Yes, this is exactly what I explained

Believe me, just try...

Activate EXTERNAL, configure FFMPEG with vMixAudio and vMixVideo virtual devices as inputs and define your options and destinations.
You can also test with VLC for easier/quicker setting, it works the same way.
vMix virtual devices are seen as any regular capture device.

Guillaume

Thank you Guillaume, I did manage. I was completely misunderstanding the ability of vMix to create virtual devices for any capturing software, including a process running in ffmpeg CLI at the same time EXTERNAL output is being activated. Your last reply was definitly clarifyng, sorry for my poor insight.
I use it as a workaround for capturing in ffmpeg the audio channel of my Magewell card which is wrongly "seen" by dshow as a 44.1 KHz device (even though with sources at higher sampling rate). So I cannot produce quality capture without resampling audio streams (as an alternative audio capture could be done with Magewell SDK tools, for example, and then remuxed with video, which is a time expensive method).

Hopefully the stream produced by vMix (through EXTERNAL) is not processed at all and so I can simply copy the PCM stream in final output.
Are we sure there is no background processing (i.e. audio resampling) by vMix in launching EXTERNAL feature? (I see in ffmpeg log the correct sample rate but it is the vMix output, while it's the stream entering vMix that I wish investigate...)

Thank you so much

Oh I just saw your edit.
I will not answer this point, I prefer Magewell specialists like Martin Kay (Zenvideo) or Tom Sinclair or (obviously) Martin to do it if they see this thread.

My opinion is : it depends on your Magewell card settings and your input and project settings in vMix.

Guillaume