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. |
14th June 2021, 00:53 | #21 | Link | |
Broadcast Encoder
Join Date: Nov 2013
Location: Royal Borough of Kensington & Chelsea, UK
Posts: 2,883
|
Quote:
I went to their website and I noticed that they're part of the streaming video alliance, a group I'm also part of. Tomorrow I'll check whether I can find one of them in our Slack group and eventually ask for a trial to test the quality. I can't promise anything though 'cause right now I'm pretty busy trying to encode Dolby Atmos into DolbyED2 without using a Dolby Hardware Encoder |
|
14th June 2021, 01:15 | #22 | Link | |
Registered User
Join Date: Jul 2003
Location: Italy
Posts: 1,135
|
Quote:
|
|
14th June 2021, 20:00 | #27 | Link |
Registered User
Join Date: Jul 2003
Location: Italy
Posts: 1,135
|
Yeah, exactly. Those AR never have perfect mod16 black bars, so on a bluray encode this means to have almost the whole movie to have blurred lines. Not so problematic when the image is clean, but if there's grain for artistic reasons or due to the filmprint, that's quite visible.
|
14th June 2021, 20:20 | #28 | Link | |
Moderator
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,752
|
Quote:
A common mistake with those encodes was to center in the middle of the 1080 pixels. But 1080 is not mod16 - the mod16 encode is 1088 with the bottom 8 pixels removed. This was a problem with MPEG-2 and VC-1 as it only supported 16x16 macroblocks. Thus proper mod 16x16 framing of a 2.4 title in MPEG-2 or VC-1 isn't 280 top and bottom, but 272 top and 288 bottom. With H.264, a 4x4 block is only 8x8 with chroma. So you can get away with mod8 from the top and bottom. 280x280 works for 2.4 in H.264. With 1.85:1 you've got 1038 active pixels out of the 1080 lines, so 42 lines to crop. 42 isn't mod8; you need to round up to 48. Blanking out 24 pixels top and bottom means covering 6 lines of the source, which may be preferable to getting the edge artifacts. Alternatively you could scale the image up to 1040 active pixels and crop 16 top 24 bottom. For 2.35:1 you've got 817 active pixels. One would mask 132 top and bottom if centering, but those aren't mod8. So, move the image up four pixels and mask 128 top and 136 bottom. |
|
15th June 2021, 13:03 | #29 | Link |
Registered User
Join Date: Jul 2003
Location: Italy
Posts: 1,135
|
Yeah, but it's something that can't be done... I mean, there's no reason to "un-center" the image just to have mod16 black bars and help x264, because it's visible by naked eye that in that way the image is not centered anymore (which is bad aesthetically). Plus, other encoders doesn't exhibit this type of flaw and a comparison with the same movie made by another distributor will made the "trick" obvious.
The suggestion seems more or less a workaround to overcome the problem... |
15th June 2021, 17:29 | #30 | Link | |
Moderator
Join Date: Jan 2006
Location: Portland, OR
Posts: 4,752
|
Quote:
And we're talking about shifting 6 pixels max out of 1080. I do not think most consumers would even notice it if you asked them if something was odd about the image. |
|
16th June 2021, 00:47 | #34 | Link | |
Derek Prestegard IRL
Join Date: Nov 2003
Location: Los Angeles
Posts: 5,988
|
Quote:
Shoot them an email, there may be a usage model for individuals / small businesses that makes sense. They're good people (and very clever). |
|
26th September 2021, 12:55 | #35 | Link | |
Registered User
Join Date: Feb 2020
Posts: 539
|
Quote:
If we are talking about 2012 tests of AVC those are wrong now. x264 devs are still fixing in 2021 quite hillarious mistakes... https://code.videolan.org/videolan/x264/-/issues/28 So no surprises there. No surprises about this about Beamr too is bad and is still based on x264 (what changed from 2013?). https://gist.github.com/Daiz/5043109 Last edited by Balling; 26th September 2021 at 14:58. |
|
26th September 2021, 18:02 | #37 | Link | |
Registered User
Join Date: Nov 2004
Location: Poland
Posts: 2,843
|
Quote:
Same as Telestream GPU accelerated x264 in Vantage. If you use no acceleration you get 2x slower encoding than x264 itself (one same machine). If you use GPU acceleration (by buying crazy expensive Tesla card and burning 100s of extra watts) you get about same speed as vanilla x264 on CPU Amazing technology... |
|
27th September 2021, 08:27 | #39 | Link | |
Broadcast Encoder
Join Date: Nov 2013
Location: Royal Borough of Kensington & Chelsea, UK
Posts: 2,883
|
Quote:
Seeing how bad and expensive Vantage was is the whole reason why I decided to contribute to FFAStrans in the first place. And if it wasn't for closed source proprietary stuff like VANC OP47 .stl subtitles mux in mxf and DolbyE encoding we would have succeeded in recreating a better open source transcoder... |
|
Thread Tools | Search this Thread |
Display Modes | |
|
|