[FFmpeg-user] NVENC HEVC Stuttering / macroblock display issue on LG TV

Zheer Zheer zheer34 at gmail.com
Fri Feb 5 12:41:42 CET 2016

Hi Carl,

I have now tried with level 3.1 and have the same problem. Running the same
command line with x265 however plays perfectly well.

ffmpeg -i sample.mp4 -y -c:v nvenc_hevc -preset slow  -s 720:576 -level
3.1   -r 24000/1001 -c:a aac -aq 128k -c:s copy  sampleNvencHEVC.ts
ffmpeg -i sample.mp4 -y -c:v libx265 -preset slow -x265-params bframes=0
-s 720:576 -level 3.1 -r 24000/1001 -c:a aac -aq 128k -c:s copy

I've also done more test, and seen differences with the GOP and bufsize
parameters that I had missed in my previous testing. I have not been able
to get a defect free video though...

Reducing GOP a lot, to say 15 helps (the default appears to be 250) - my
take is something goes wrong playing the P frames and the I frame wipe
things clean..  X265 is using a 250 GOP though so why would it not work
with NVENC ..
The buffsize also delayed the apparition of macroblock issues. the command
line above resulted in a VBR of 2.5M so I've tested with bufsize from 500k
to 10M - the best result was around 2M but it only just delayed the problem
showing up

Any other thoughts ?

Many thanks

> The original frame rate which is 23.976. setting in to -r 24 seems to work
> too, but with other framerates (20, 25, 30), I'm seeing stuttering issues.
> > > - HEVC levels 4.1 to 5.0
> > - Did you also try lower levels?
> I have not tried lower than 4.1 with HEVC (the encoder returned an error
> from 4.0, probably because the resolution / bit rates I used were higher
> than allowed at 4)

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