Doom9's Forum - View Single Post - Intel SVT-HEVC encoder

dipje · 20th February 2019, 08:42

I've done a very short (and wrong ) test with 1.3 compiled into ffmpeg 4.1.

I've re-encoded a 5 second clip Sony 1920x1080 25fps h264 +/- 50mbit slog2 that had a small object moving fast.
As a baseline tried starving the codecs a bit.
X264 preset slow, two pass 500k bitrate, yielded a VMAF +/- 76.
X265 preset medium two pass 500k bitrate, yielded a VMAF +/- 86 (but was slower to encode )
Libsvt_hevc vbr to actually hit around 600k (single pass always ) , yielded a VMAF of +/- 75.

Tried again in cqp mode , changing the qp to hit a bitrate of about twice that. Than tried x264 in preset slow with CRF mode, adjusting the CRF value to get a final filesize that is just under the libsvt one. Svt hit VMAF of 80, x264 VMAF of 86.

So, this isn't a serious test at all. Just a little start for me. The clip is too short, it's ungraded, VMAF doesn't tell you all there is, etc...
But svt seems fast but sacrifices Soo much in the quality that x264 can match it for not that much slower.

It's a software only solution that encodes real-time easily on my 8-series i5 ultrabook...but does not offer Soo much value for 1920x1080 for me it seems.

Again, wrong test so don't take it for granted . Files with proper contrast and 4k would be a much more interesting case.

20th February 2019, 08:42	#4 \| Link
dipje Registered User Join Date: Oct 2014 Posts: 268	I've done a very short (and wrong ) test with 1.3 compiled into ffmpeg 4.1. I've re-encoded a 5 second clip Sony 1920x1080 25fps h264 +/- 50mbit slog2 that had a small object moving fast. As a baseline tried starving the codecs a bit. X264 preset slow, two pass 500k bitrate, yielded a VMAF +/- 76. X265 preset medium two pass 500k bitrate, yielded a VMAF +/- 86 (but was slower to encode ) Libsvt_hevc vbr to actually hit around 600k (single pass always ) , yielded a VMAF of +/- 75. Tried again in cqp mode , changing the qp to hit a bitrate of about twice that. Than tried x264 in preset slow with CRF mode, adjusting the CRF value to get a final filesize that is just under the libsvt one. Svt hit VMAF of 80, x264 VMAF of 86. So, this isn't a serious test at all. Just a little start for me. The clip is too short, it's ungraded, VMAF doesn't tell you all there is, etc... But svt seems fast but sacrifices Soo much in the quality that x264 can match it for not that much slower. It's a software only solution that encodes real-time easily on my 8-series i5 ultrabook...but does not offer Soo much value for 1920x1080 for me it seems. Again, wrong test so don't take it for granted . Files with proper contrast and 4k would be a much more interesting case.