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. |
15th November 2015, 11:27 | #23 | Link |
Registered User
Join Date: Oct 2013
Posts: 24
|
The thread and links posted are there for any idiot with two eyes to take a look at.
What I am convinced of is that ffmpeg is not a haphazard little project, and that its docs have more merit than some random person on a forum. Not 100% certain that it's better, but I certainly got no definitive answers, here. Last edited by xyzone; 15th November 2015 at 11:30. |
15th November 2015, 13:13 | #24 | Link |
ангел смерти
Join Date: Nov 2004
Location: Lost
Posts: 9,558
|
vp9, on the other hand, is a haphazard little project that seems more poorly managed than a lot of community projects. Google only seems to care about it as far as it can be used to reduce Youtube's bandwidth bills, and any attempt to mimic x264's and x265's excellent command line, multicore use, rate control, and exhaustive documentation are basically ignored.
I gave the new release a shot, but I didn't bother with a full test suite, it wasn't noticeably faster than 1.4 nor any better quality in the first (although some artifacts changed). They haven't updated the rate control, so what's the point in testing two-pass, it'll still be just as wildly off. Maybe it's just ARM optimizations. Edit: Missed that this was a splinter thread, not the main VP9 thread. |
19th November 2015, 23:37 | #25 | Link |
Registered User
Join Date: Oct 2013
Posts: 24
|
I found a compromise to get some kind of quick seeking (in most cases). 2-pass with '-auto-alt-ref 1' on pass 2. Overall, this is how I'm getting better results on low resolution content, especially flat pixels video:
ffmpeg -i [input] -c:v libvpx-vp9 -b:v 0 -crf 28 -threads 4 -speed 1 -f webm -pix_fmt yuv420p -profile:v 0 -an -sn -pass 1 /dev/null ffmpeg -i [input] -c:v libvpx-vp9 -b:v 0 -crf 28 -threads 4 -speed 1 -f webm -pix_fmt yuv420p -profile:v 0 -an -sn -pass 2 -auto-alt-ref 1 -lag-in-frames 25 [output].webm In a way, that's even more desirable, because it tends to seek where the scene changes. But if the pixels on screen never completely swap out, still no fast seek with ffmpeg vp9 constant quality. |
19th November 2015, 23:44 | #26 | Link | |
Registered User
Join Date: Jun 2013
Posts: 95
|
Quote:
__________________
https://github.com/MoSal |
|
20th November 2015, 10:10 | #27 | Link |
Registered User
Join Date: Oct 2013
Posts: 24
|
The problem with that is that it tends to add size to some encodes.
I encoded a 3 minute sample of content I knew would produce the seeking issue, despite auto-alt-ref. First with -g 250, then without. All else the same. The gop set file is 30,979,544 bytes. The file without gop set is 28,246,134 bytes. Not much, but there's still a difference. So I guess bigger file size is the price for guaranteeing some kind of quick seek. Be that as it may, with or without gop, auto-alt-ref still helps a lot in most videos, and this makes vp9 more usable for my purposes. Last edited by xyzone; 20th November 2015 at 10:20. |
20th November 2015, 10:30 | #28 | Link |
Registered Developer
Join Date: Mar 2010
Location: Hamburg/Germany
Posts: 10,344
|
Of course. For proper seeking you need more I frames, and I frames take up space.
__________________
LAV Filters - open source ffmpeg based media splitter and decoders |
22nd November 2015, 06:51 | #29 | Link | |
Registered User
Join Date: Nov 2015
Posts: 1
|
Pass "-g seconds" as an encoding parameter
Quote:
http://ffmpeg.org/ffmpeg-all.html#libvpx https://github.com/Kagami/webm.py/wi...tings#defaults https://chromium.googlesource.com/we...x_iface.c#1440 Regards |
|
Tags |
seek, vp9 |
Thread Tools | Search this Thread |
Display Modes | |
|
|