Page 1 of 1

av1 getting worse results than hevc (h265)

Posted: Wed Mar 20, 2019 7:16 am
by abcjme
I converted an avc (h264) file to an hevc (h265) file and an av1 file.

Relative to the hevc (h265) file, the av1 file is far larger in size, and the av1 file has worse psnr and ssim results too.

With the hevc (h265) file, i used the default crf setting (28)

av1 doesn't have a default crf amount, but i used the ffmpeg recommendation of 30

Here's the command i used to do the hevc (h265) conversion

C:\Users\l\Desktop\6-app\ffmpeg -i y.mp4 -c:v libx265 -preset 8 -vf scale=1920:1080 -r 60 -ab 192k -ar 48k -map_chapters -1 -map_metadata -1 z.mp4

Here's the command i used to do the av1 conversion

C:\Users\l\Desktop\6-app\ffmpeg -i y.mp4 -c:v libaom-av1 -crf 30 -b:v 0 -strict experimental -vf scale=1920:1080 -r 60 -ab 192k -ar 48k -map_chapters -1 -map_metadata -1 z.mkv

Here are the psnr and ssim results of the hevc (h265) file

ssim

Y:0.981764 (17.390662)
U:0.992258 (21.111573)
V:0.992246 (21.104816)
All:0.985260 (18.315015)

psnr

y:41.620801
u:48.257839
v:47.699066
average:42.905441
min:38.873493
max:58.862531

Here are the psnr and ssim results of the av1 file

ssim

Y:0.923286 (11.151250)
U:0.991684 (20.800862)
V:0.987425 (19.004970)
All:0.945376 (12.626126)

psnr

y:27.332443
u:44.955360
v:41.569108
average:29.034062
min:8.783696
max:59.518112

Here are the size results of the files

avc

3.9 mb

hevc (h265)

4.6 mb

av1

9.59 mb

I know i'm compressing an already well-compressed file, I didn't necessarily expect a smaller file size - but i did expect av1 to outperform hevc (h265))

Here are the actual files

https://www.dropbox.com/s/4xy7tsys5cswn ... iginal.mp4

https://www.dropbox.com/s/fnakxv248sz8w ... 3-hevc.mp4

https://www.dropbox.com/s/07x5ddc54jn7x ... -3-av1.mkv

Why would such poor results occur?

Re: av1 getting worse results than hevc (h265)

Posted: Fri Mar 22, 2019 5:09 pm
by Zeranoe
ssim and psnr are not a great indication of visual quality. Also note that if you're comparing x265 you need to use the proper tune settings or the results are useless.

Re: av1 getting worse results than hevc (h265)

Posted: Mon Mar 25, 2019 10:25 am
by pandy
At first always setup properly your encoders especially when comparison is your goal.

To setup AV1 follow guidelines https://trac.ffmpeg.org/wiki/Encode/AV1

You may find this site useful https://streaminglearningcenter.com/

Re: av1 getting worse results than hevc (h265)

Posted: Mon Mar 25, 2019 7:57 pm
by abcjme
Zeranoe wrote:
Fri Mar 22, 2019 5:09 pm
ssim and psnr are not a great indication of visual quality. Also note that if you're comparing x265 you need to use the proper tune settings or the results are useless.
? if not psnr or ssim, then what's a good comparison
? what are the proper tune settings of x265

Re: av1 getting worse results than hevc (h265)

Posted: Mon Mar 25, 2019 7:58 pm
by abcjme
pandy wrote:
Mon Mar 25, 2019 10:25 am
At first always setup properly your encoders especially when comparison is your goal.

To setup AV1 follow guidelines https://trac.ffmpeg.org/wiki/Encode/AV1

You may find this site useful https://streaminglearningcenter.com/
· that was the guide that i used

Re: av1 getting worse results than hevc (h265)

Posted: Tue Mar 26, 2019 2:32 pm
by pandy
Then perhaps AV1 is still far from being mature enough to be used.