[FFmpeg-user] Buffer Underflow in case of high resolution mpeg1video encoding

[inge]

Hello,

I've been using ffmpeg to encode raw data using the following command line
argument:

ffmpeg -r 24 -pix_fmt rgba -s 2560x1440 -f rawvideo -y -i - -c:v mpeg1video
-qscale:v 4 -vf vflip filename.mpeg

During encoding I get the following output:
[mpeg @ 000000000434c3c0] buffer underflow st=0 bufi=234679 size=263328
[mpeg @ 000000000434c3c0] packet too large, ignoring buffer limits to mux it
[mpeg @ 000000000434c3c0] buffer underflow st=0 bufi=234679 size=263328
[mpeg @ 000000000434c3c0] buffer underflow st=0 bufi=236708 size=263328
[mpeg @ 000000000434c3c0] packet too large, ignoring buffer limits to mux it
[mpeg @ 000000000434c3c0] buffer underflow st=0 bufi=236708 size=263328
...

I noticed that using a lower resolution, for example 1920x1080, does not
give me a buffer underflow.
Also using a qscale of 5 instead of 4 prevents it.
It's also interesting to note that the output seems to be fine, despite
these messages.

Can someone help me understand what exactly a buffer underflow means in this
context? And/Or how to prevent it from happening? I've searched around for
some time now and I'm still none the wiser.

Much appreciated!
Inge 



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