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DWAM  
#1 Posted : Sunday, August 9, 2020 3:34:32 AM(UTC)
DWAM

Rank: Advanced Member

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Joined: 3/20/2014(UTC)
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France
Location: Bordeaux, France

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Hi !

I'd like to use Newtek NDI Virtual Input to feed FFMPEG for live encoding to other protocols but I cannot get it to run smoothly and it results in choppy or slomo video, rtbufsize errors, framedrops and cracking audio.

Here's my context :
- Windows 10 64 Bits
- FFMPEG from Zeranoe (latest stable build 4.3.1)
- NDI feeds come from vMix (or OBS or other NDI tools) and they all play fine everywhere except with FFMPEG (I have perfect playback with NDI Tools, other vMix/OBS/VLC or Zoom/Skype/WebRTC, etc... they're all working perfectly)

Here's my commandline for FFplay

> ffplay -f dshow -rtbufsize 512M -i video="NewTek NDI Video":audio="Ligne (NewTek NDI Audio)"

> the console returns "real-time buffer [NewTek NDI Video] [video input] too full or near too full (62% of size: 512000000 [rtbufsize parameter])! frame dropped!" and the playback is not good at all

I have also tried with option "-fflags nobuffer" or with a larger (insane?) values for buffer size (-rtbufsize 1024M/2048M). Also tried to specify more options (which help sometimes) like "-vcodec rawvideo" or "-video_size 1920x1080 -framerate 25" but nothing works... Even the FFPROBE utility which only analyses the input reports rtbufsize errors!

Obviously it does the same with FFMPEG so any further conversion (to SRT in my use case) is terribly bad too.

I have tons of scripts using DSHOW devices in FFMPEG, it's not always easy, but this time, I feel completely stuck. Am I missing something? Has someone managed to get NDI Virtual Input work when used as a DSHOW device in FFMPEG?

Any help appreciated! Thanks
Guillaume, aka DWAM
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