On Mon, 25 Nov 2019, Dennis Mungai wrote:

Hello there,

Are there any known caveats to using -re with UDP streams as input, such as
packet loss?

I’ve seen the -re option being discouraged with the likes of RTP, does the
same apply to mpegts UDP streams?

Yes. -re is widely misundetstood for some reason, despite that it is documented reasonably well:

-re (input)
Read input at native frame rate. Mainly used to simulate a grab device, or live input stream (e.g. when reading from a file). Should not be used with actual grab devices or live input streams (where it can cause packet loss). By default ffmpeg attempts to read the input(s) as fast as possible. This option will slow down the reading of the input(s) to the native frame rate of the input(s). It is useful for real-time output (e.g. live streaming).

So you only need -re if you want to limit reading your input to realtime speed in order to generate your output at realtime speed. If your input is already realtime, then you don't need it. If your output is inherently realtime (e.g. decklink), you don't need it either.

Regards,
Marton
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