Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion. Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules. |
20th June 2019, 23:55 | #1741 | Link | |
Moderator
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,770
|
Quote:
I don't see any software decoder solution becoming mainstream, since we have more than good enough HW codec options now. Fingers crossed that all AV1 HW decoders include 10-bit support. It would be great to have a codec out there where >8-bit support is guaranteed. |
|
21st June 2019, 04:46 | #1743 | Link | |
Registered User
Join Date: Jan 2006
Posts: 41
|
Quote:
VP9 has 10-bit support only from profile 2 on, where profile 0 and 1 are 8-bit only, which is why 10-bit HW support is less common. |
|
22nd June 2019, 07:51 | #1744 | Link | |
Registered User
Join Date: May 2005
Location: Swansea, Wales, UK
Posts: 196
|
Quote:
I'd say that the progress so far is pretty incredible for such a young codec, decoder and encoder wise. From what I remember it also took a while for the OpenHEVC decoder library to get optimised, and they weren't concentrating on mobile nearly as much as the AV1 groups seem to be - though the increased core counts and IPC of current ARM implementations may have influenced that focus to some degree. |
|
22nd June 2019, 08:22 | #1745 | Link | |
Registered Developer
Join Date: Mar 2010
Location: Hamburg/Germany
Posts: 10,346
|
Quote:
Work on 10-bit has started now, but due to the nature of the beast, SIMD stuff cannot be easily ported from 8-bit to 10-bit, so its a lot of work still.
__________________
LAV Filters - open source ffmpeg based media splitter and decoders |
|
27th June 2019, 09:09 | #1746 | Link |
Registered User
Join Date: Aug 2009
Posts: 201
|
Lots of interesting talks at the Big Apple Video event (that's Apple as in New York, not Mac Os X):
Probably the most interesting for this group is the second half of Ronald Bultje's talk which covers his Eve-AV1 encoder and some conparisons with other codec and encoders: But lots of other interesting stuff from other speakers too if you click through to the channel to see the full list. I'll also mention this one from Cisco as it's got a kind of boring sounding title but had some interesting stuff around complexity Vs speed in AV1 after the live demos. |
27th June 2019, 17:03 | #1747 | Link |
Registered User
Join Date: Jan 2007
Posts: 729
|
I wonder how much does VMAF really speak about visual quality and compression efficiency while keeping detail (as opposed to the usual issue with metrics, the "blur more for maximum PSNR/SSIM" effect), seeing how in those slides, *everything* except Rav1e and x264 is shown as matching or outdoing x265. Well, I guess there's already the usual assertion/claim that x265 = lipvpx-vp9 that raises questions. I always stop wondering at that point in these presentations...
Last edited by mandarinka; 27th June 2019 at 17:12. |
27th June 2019, 19:12 | #1748 | Link |
Registered User
Join Date: Aug 2009
Posts: 201
|
My theory is that the people hired for the subjective tests that underly the objective stats or that vote VP9 as very slightly better than x265 in the MSU tests on subjectify.us have a different notion of quality than the kind of person who is interested in codecs for their own sake.
Like, I read a paper recently where someone was applying their grain synthesis approach to HEVC and the subjective tests they did to prove it worked showed they could get basically all the subjective benefit by just doing the noise removal step and not bothering to add the grain back in, something that could be done by any encoder, for any codec (and I'm guessing this makes up part of the secret sauce of some encoders). But I guess someone who said they could get a massive increase in subjective quality via the Psy optimisation of basically blurring the input would get some pushback on that view in some quarters, even with subjective tests to back it up. Link to the paper. It seems at higher qualities the people saw the added grain as a defect rather than a quality improvement (though still a statistical tie mostly). https://arxiv.org/abs/1904.11754 Last edited by dapperdan; 27th June 2019 at 19:52. |
28th June 2019, 16:29 | #1749 | Link |
Registered User
Join Date: May 2005
Location: Swansea, Wales, UK
Posts: 196
|
Having watched some (but not all) the BAV presentations - I know that AV1 is currently not ideal for running a battery of tests at short notice, but did they really need to use such outdated versions of competing codecs?
Im pretty sure that the x265 build was from January, and the libaom build from february in one of them. Maybe I'm missing something and those builds were picked for stability? |
1st July 2019, 17:33 | #1753 | Link | |
Registered User
Join Date: Feb 2003
Location: New York, NY (USA)
Posts: 109
|
Quote:
|
|
1st July 2019, 17:41 | #1754 | Link | |
Registered User
Join Date: Feb 2003
Location: New York, NY (USA)
Posts: 109
|
Quote:
So basically - ignoring x264 for a second (which is pretty mature/stable) - some from late April and some from early June, none from January or February. |
|
1st July 2019, 19:30 | #1755 | Link |
Registered User
Join Date: May 2005
Location: Swansea, Wales, UK
Posts: 196
|
Ah, must have misread the presentation then, easier for me to read from slides than video - still the position of rav1e seems odd, it shows on graphs to be still hovering around x264 - I could have sworn it passed x264 months ago, and then nothing has been said since despite all the work commits being merged into it.
Is it still suffering that regression from awhile ago? "I believe that because the conference was organized by Vimeo/Mozilla, who just announced a partnership around rav1e, they wanted to prevent a potential conflict of interest in talk selection and decided to not give a talk on it." Yes that makes sense, just seemed a little odd, like going to WWDC and getting nothing from Apple - still they got a lot of mentions from the presenters in any case. Last edited by soresu; 1st July 2019 at 19:40. |
1st July 2019, 21:55 | #1756 | Link |
Registered User
Join Date: Aug 2015
Posts: 34
|
The rav1e stats are correct. We still fall behind on high bitrate VMAF - most likely due to that being more sensitive to activity masking (aq) which is still in progress by s_p.
The multithreading performance is limited by a serialization point of the loop filters between frames (by far the slowest part of rav1e right now). There's some outstanding PRs to make it better, e.g. https://github.com/xiph/rav1e/pull/1396 |
1st July 2019, 22:02 | #1757 | Link |
Registered User
Join Date: Aug 2009
Posts: 201
|
The Visionular talk from Zoe Liu used builds from Jan and Feb.
I think the x265 release used was the last stable release so that doesn't seem too crazy. You could easily cry foul if someone used a non stable git commit and it performed worse than expected due to hitting a bug. It's also worth bearing in mind that that was basically the same talk as given at the Agora.io thing, so some people tour these things around for a while, it's not ridiculous for them to reuse slides and not have something fresh for every talk they give. Fairly certain I'd seen the NGCodec talk slides before too. |
2nd July 2019, 17:53 | #1758 | Link | |
Moderator
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,770
|
Quote:
|
|
2nd July 2019, 18:11 | #1759 | Link | |
Moderator
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,770
|
Quote:
Also, VMAF isn't static. Netflix comes out with new ML models that will give different (and more accurate) scores compared to older models. It can be estimated for mobile, 1080p, or UHD devices. The scores vary based on the resolution of comparison (720p tested at 720p will deliver higher scores than 720p tested at 1080p, compared to 1080p encoding). And it is a per-frame metric, and how to aggregate per-frame scores into an overall clip quality is an unanswered question. Using a harmonic mean helps, but even that is probably only useful for <20 second durations. A single VMAF score for a whole movie or episode could indicate highly variable quality or highly consistent quality. None of this is a diss on VMAF. Netflix did what they set out to do well, put a huge amount of effort into it, and made reasonable design decisions. But like all metrics, it measures what it is designed to measure, not what we wish it measured . I've seen VMAF do a poor job of detecting:
And it doesn't do HDR at all. It used to not do UHD, but does now. Another problem with a popular metric is that developers start tuning for that metric instead of what the metric is supposed to measure (subjective quality in this case). When developers start tuning for metrics over eyes, the correlation of that metric to subjective quality actually gets WORSE. So, for an encoder like libaom that got tuning based on VMAF ratings, we'd expect that its VMAF scores would be higher relative to actual subjective quality than for encoders that weren't tuned that were. But it'll be better than ones tuned for PSNR, like the vp? series. Not that tuning for VMAF is a bad strategy. But it does result in less meaningful VMAF scores. |
|
2nd July 2019, 18:17 | #1760 | Link | |||
Moderator
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,770
|
Quote:
That said, I've not seen any study demonstrating better subjective quality from a well-tuned libpvx encode versus a well-tuned x265 encode, using the same bitrate @ time. Quote:
Quote:
There are similar debates about TV's default "vivid" mode. Some people claim to like it, even though what's displayed in manifestly wrong on many axes. |
|||
Thread Tools | Search this Thread |
Display Modes | |
|
|