Understanding VP9 vs HEVC

[glenpinn]

Hi everyone, this is not really related to VRD but i thought i might ask the question anyway.

Ok so i have been downloading several video files from Youtube testing various video downloader tools, the 4k files in youtube are either 30p or 60p.

So it turns out that no matter which 4k file i download, it comes down at 30p only, and it is in an MKV container, in the VP9 codec, which i was not aware of, but i am kind of in the dark about this VP9 codec.

Can someone explain VP9, and has it been developed as a competitor to HEVC, and is one actually better than the other.

My issue too is having VP9 files but they may not be supported on newer 4k smart TV's where HEVC is generally supported now days, but if i had no support on my 4k tv for VP9 then i would need to recode the files to either HEVC or AVC.

I have used my VRD Pro to recode one of the 4k/30p VP9 MKV files to HEVC, and boy it really doesn't like it very much.

The 4k/30p VP9 MKV file is 8 minutes duration and 1gb file size, i recoded it to 4k/30p HEVC in the same MKV container, and it took 40 minutes on my 6 core laptop, with the CPU running at around 90% average usage, BUT the output file size was 2gb ?????

I can upload the Log filefor the recode if anyone wants to see it, i can also offer a download link to the 4k file that i got from Youtube.

Cheers

 

[Danr]

Hi Glen, Haven't heard from you in a while When recording from VP9 to HEVC in VRD Pro you'll need to manually set the bit rate in the output profile since VRD doesn't have a bit rate scaling factor build in for VP9 to HEVC. For VP9 to HEVC I would suggest a 1 : 1 ratio, i.e. a 2 Gbps VP9 source should be encoded to a 2 Gbps HEVC. You'll get much faster encoding using H264/AVC although the bit rate should be in the range of 1 : 1.5 to 1 : 2.0. From what I've read, VP9 quality at a given bit rate is similar to HEVC and the codec was primarily developed to bypass intellectual property issues with HEVC, not for technical reasons.

FYI, HEVC encodes much, much faster on a GPU than on a CPU.

 

[glenpinn]

Hi Dan, thanks for that info.

As for GPU encoding, years ago i always had an Intel CPU with the built in HD or Iris Pro graphics, so i would always use Intel QuickSync for encoding as it was supposed to be faster, my current 6 core laptop has HD Graphics on the CPU, but it also has an Nvidia GTX-1050 dedicated card as well, but i have been using Software encoding ever since i started using VRD Pro, believing it is better than GPU encoding is as far as quality goes, and many others also agreed with this too, however these days this may well have changed.

This arvo i ran some encoding tests using the 8min Youtube video that i downloaaded, the file was 1gb in size, VP9 codec in an MKV container, and the bitrate is 15.5Mb/s

I recoded it to 4k/30p HEVC MP4 using VRD Pro using Software, Intel Quicksync and Nvidia NVEnc and i manually set the output bitrate to 16Mb/s

I was shocked at the results, not so much the file output file sizes, which were all very close to the source file size, but the output Times were all so different, as you can see in the image that i made for all 3 encodes.

I would have thought that the Quicksync would trash the NVEnc but it was quite the opposite, 8 minutes for NVEnc vs 17 minutes for Quicksync vs 35 minutes for Software

Most experts that i have asked regarding which of these 3 encode types would produce better quality, and all told me that if i play the VP9 source file on my 65" 4k tv, and then play the 3 encoded HEVC files, if i can't physically see any difference then use the one that i would prefer to use.

In every other aspect, all 3 output files are the same, or very similar.

 

[Danr]

Glen, If you want to send me the files I can compare them here to measure the quality changes via PSNR and SSIM.

 

[glenpinn]

Hi Dan, i have sent you an email @ support with the download links for the source file and 3 VRD test files.

The shortest 4k/30p VP9 file i had from youtube was the 8 minute one, which was 1gb in size, and the 3 conversions were also about 1gb, so i cut the last 5.5 minutes from the source file and did 3 new outputs so each of the VRD files were only 2.5 minutes long, saving on the download time.

I tested the 4k/30p VP9 youtube file on my 65" LG 4k TV and it works fine, so what i read about most TV manufacturers now supporting VP9 playback seems to be correct.

Also, VRD is so laggy when trying to cut/trim bits off on the timeline with these 4k/30p VP9 files, but when i try cutting the recoded 4k/30p HEVC MP4 output file on the timeline it is almost perfect.

I am so glad that so far Camera manufacturers have not implemented VP9 as a recording codec because i definitely would never use it if i had to edit the files, don't know how other editing software would handle those VP9 files.

I am just about to buy my new GoPro Hero 9 action camera, and a bunch of accessories for it, and i will be building my own custom made camera rig to mount everything on, need to keep it as small and compact as i can.