[FFmpeg-user] Documentation/examples about async protocol
omega_canta at yahoo.com
Mon Apr 1 04:59:50 EEST 2019
I'm interesting in using the async protocol, which I discovered a few
hours ago. I believe it may solve a problem I'm facing with my video
However, this is the documentation page about the async protocol:
It only has a very brief description of what it does, and has a very
generic syntax example.
Following that very example, I've tried the following setup:
# ffmpeg instance 1
ffmpeg -f lavfi -re -i "testsrc" -c:v libx264 -preset veryfast -r 30 -f
# ffmpeg instance 2
ffmpeg -i "async:udp://localhost:3000?pkt_size=1316" test.mp4
That gave me lots of "data loss" error ("part of datagram lost due to
insufficient buffer size", "Missing reference picture", "Invalid NAL
unit", etc), and an extremely noisy output.
So I've tried to tune it up, ending up with this command line:
ffmpeg -y -re -i
-c:v libx264 -preset veryfast -r 30 test.mp4
But same results.
ffplay can reproduce "instance 1" fine, and if I don't use the async
protocol on "instance 2" it also works fine.
Without extra parameters or some kind of fine tuning, the async protocol
seems unusable even for the most basic use cases. I would like to tune
up, for example, the buffer size ffmpeg tells me insufficient. However,
I can't find any async buffer setting; in my previous example, that
buffer_size parameter is for the udp protocol, and not async. I can't
also find anywhere on google a single example of anyone using the async
So, my question is: is there any usage example for the async protocol,
or any setup parameters I can use?
Thanks in advance.
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