View Full Version : Re-encoding movie collection
Blinky7
8th July 2015, 22:27
Hello there. I have about 2tb of web-dl tv-episodes that I have watched but dont want to delete them. However 2tb is a lot of space and I need to free some of it.
I am playing around these days with Handbrake and x265 and the results are very impressive, so I am thinking of encoding them all with HEVC to save on storage.
I have a couple of questions though :
1) What CRF would be appropriate for a web-dl episode at 720p/1080p ?
2) Handbrake does not support 10bit HEVC, is this something I should be concerned about? Should I keep on with 8bit or should I find another utility that supports 10bit?
(this question has 2 sub-questions actually : a)Do you gain more quality at the same bitrate with 10bit to make it worth it? b)In the future when desktop players/TVs will support HEVC, will they be able to playback 10bit?
3) In the audio department, I am thinking of downmixing 5.1 (most web-dl are 5.1) to Stereo, since TV episodes are usually playbacked on the TV or using headphones on my PC. What should I choose there? HE-AAC 128bit or?
4) What other settings should I use? I especially dont know about the profile (none, main, main10?)
Please help me reach the optimal settings so that I can start to encode my whole collection, because if I change my mind in the middle everything will be wasted till that point :P
a_nAvika
9th July 2015, 07:14
1. It is better use bit-rate based rate control compared to CRF for achieving desirable compression ration. You can set the bit-rate to 60% to 70% of current file size.
3. IMO it is better to keep the audio untouched as it would take considerably less percentation of data compared to its counterpart video. And it might be useful when you want to watch your collection in a home theatre system
4. You can use main profile if your video is 8 bit and main10 if its 10bit with level 5.1. You can configure the encoder to generate best quality output with 7 B frames as it is offline encoding.
sneaker_ger
9th July 2015, 09:31
b)In the future when desktop players/TVs will support HEVC, will they be able to playback 10bit?
TVs and PCs (e.g. MPC-HC/LAV or Windows 10) already support 10 bit HEVC today.
Blinky7
9th July 2015, 13:54
1. It is better use bit-rate based rate control compared to CRF for achieving desirable compression ration. You can set the bit-rate to 60% to 70% of current file size.
3. IMO it is better to keep the audio untouched as it would take considerably less percentation of data compared to its counterpart video. And it might be useful when you want to watch your collection in a home theatre system
4. You can use main profile if your video is 8 bit and main10 if its 10bit with level 5.1. You can configure the encoder to generate best quality output with 7 B frames as it is offline encoding.
I want to use CRF-based encoding, because efficient bitrate-based requires 2 passes and it will take ages....and CRF-based will try to keep quality constant so if a show is mostly chit-chat it will take less space, and if there is action it will take more, so overall it is more efficient as it uses higher bitrate only when it is needed...
Finally, I don't plan on saving the files in optical media so there is no need for exact filesizes...I just want the 2tb to become maybe roughly 1tb or something...
What Gui-encoder can I use to encode in 10bit? Because handbrake does not support it (or is there someway to add it there?)
That about 7b frames and offline I have no clue what is, maybe explain it a bit more? I am kinda noob here, my only knowledge is from DivX encodings 10years back
TVs and PCs (e.g. MPC-HC/LAV or Windows 10) already support 10 bit HEVC today.
I know PCs have no problems, what I am interested in is if a desktop media player (ala WDTV) os a television will support 10bit from the start...
I currently have a Sony 46W905 that was a high-end model last year, but I doubt they will update it to add support :( (even though it has quadcore processor etc)
Is there any guide on CRF levels? I noticed that a 1.2gb 720p episode becomes about 550mb with crf20 and 350mb with crf25... To be honest I am struggling to see the difference on my PC screen, maybe the source file is not that detailed in the first place...
sneaker_ger
9th July 2015, 14:13
I know PCs have no problems, what I am interested in is if a desktop media player (ala WDTV) os a television will support 10bit from the start...
I have no idea what "start" you are talking about. As I said: TVs with these things are already on the market today (and have been for a while). Your decision to buy a TV without such support does not change that. The "big" media player brands like Chromecast, WDTV, Apple etc. have not yet released HEVC capable devices as of now but they will sooner or later as UltraHD (from TV over BluRay to Netflix) will mainly be 10 bit HEVC.
Blinky7
9th July 2015, 14:21
I have no idea what "start" you are talking about. As I said: TVs with these things are already on the market today (and have been for a while). Your decision to buy a TV without such support does not change that. The "big" media player brands like Chromecast, WDTV, Apple etc. have not yet released HEVC capable devices as of now but they will sooner or later as UltraHD (from TV over BluRay to Netflix) will mainly be 10 bit HEVC.
"from the start" means that maybe the broad range of devices that support HEVC might only support 8bit and a couple of years would have to pass till every device supports 10bit decoding.
Think of it like, let's say Sigma releases a cheap chip that decodes 8bit HEVC and a more expensive one that decodes 10bit HEVC too. Then most consumer devices could opt for the cheaper version (just to shout "hey I support H.265") and only higher-end/fewer devices go for the expensive one. Until a couple of years later the new chips have arrived and practically as technology evolves ebey chip supports 10bit.
I am not saying this has/will happen, I am just explaining the reasoning behind my question
For example, for H.264 in the begining it was not unusual to have problems with devices that did not support every level of it and could not playback the file at all due to a tiny setting in the way it was encoded...
I am going to 95% be playbacking these files from HTPC, however If I am gonna convert all of them to HEVC I would like to have covered all the bases on encoding settings beforehand.
sneaker_ger
9th July 2015, 14:41
I understand and think there is such a divide between cheap and expensive SoCs going on but mainly for mobile devices like smartphones/tablets within the next years. I think for TVs and desktop players it will not be a big problem, i.e. while there certainly will be devices limited to 8 bit the choice of 10 bit players will be sufficiently huge.
Blinky7
9th July 2015, 14:52
ok, then, assuming support is not a problem, are there sufficient gains from 10bit encoding? Is it worth it?
Moreover, any suggestions on perception of quality and CRF levels? I mean, does 20 correspond to a very good level of quality retention? Medium? Based on the quality of web-DL files what would probably be the ideal level?
smegolas
9th July 2015, 15:42
Re-encoding a low quality collection is not a good idea. It will take a long time (do you value your time?) and by the time you are finished you will notice how bad the videos look and wish you had not deleted the originals.
2TB is nothing, if you are running out of space just buy more storage. Think about how much money you will spend by maxing your processor for thousands of hours.
It would be different if you had access to the source files.
benwaggoner
9th July 2015, 16:10
What Gui-encoder can I use to encode in 10bit? Because handbrake does not support it (or is there someway to add it there?)
Unless your source is 10-bit, I don't know that there is any point in encoding HEVC in 10-bit. I've not seen the same kind of quality/size improvements in HEVC as are seen in H.264 8-bit v. 10-bit. 8-bit is definitely more compatible, particularly for mobile devices.
It'd be lovely if 10-bit becomes universal, but there will be plenty of 8-bit only HEVC implementations for years to come. Smart TVs are the main place where 10-bit HEVC is generally available today, and there are some exceptions even there. Although AFAIK all UHD models support 10-bit, and all HDR-capable TVs have to support 10-bit up to Level 5.1.
But I don't know of any mobile devices shipping that do 10-bit, and there are SoC designs without 10-bit that'll be going into 2016 devices.
ok, then, assuming support is not a problem, are there sufficient gains from 10bit encoding? Is it worth it?
Moreover, any suggestions on perception of quality and CRF levels? I mean, does 20 correspond to a very good level of quality retention? Medium? Based on the quality of web-DL files what would probably be the ideal level?
While I have yet to measure this myself, it is said that 10-bit is better than 8-bit regarding banding issues. Even if your source is 8-bit.
Considering CRF with x265, I consider 21 to be a strict minimum as higher values will tend to produce artifacts around moving objects (especially if your source isn't the best like a WEB-DL). It'll save you up to 75% space.
18-19 is a good bet quality-wise and should still save you 15~30% space.
I usually don't go lower as bitrates start to match those of x264 and there is still this "x265 washing" effect while x264 looks better for fine details.
foxyshadis
10th July 2015, 10:46
While I have yet to measure this myself, it is said that 10-bit is better than 8-bit regarding banding issues. Even if your source is 8-bit.
If you want the unbanded power of 10-bit, you have to manually deband your video beforehand first (or start with an exceptionally clean, dithered source). If your source sucks, you probably already have plenty of banding issues and re-encoding will only make them worse, so working in 16-bit mode you must use your favorite denoiser plus f3kdb or gradfun2dbmod, before feeding it to x264/x265 10-bit. If your source is still pretty noisy and you plan to keep the grain, you'll get nothing out of 10-bit.
Blinky7
10th July 2015, 16:22
I decided to stay with CRF-20 and 8bit at Medium, based on your responses. It sill saves about 55% space, and quality seems very good. To be honest even CRF23 seems decent in my eyes but I think it is pushing it a lot when CRF20 already provides such massive filesize gain.
Can I get any ideas on Audio? I am thinking of downmixing them all to Stereo, since 5.1 is useless for TV episodes except for very rare occasions (action like 24) and I am 99% watching these either on the TV (2 speakers) or with headphones.
However what codec and bitrate should I use? My tests were done with HE-AAC at 128kbps , are there any thoughts on this?
PS: At Medium I get like 25fps average on 720p and 14fps on 1080p , is this optimal? I think next level (slow) drops massively in speed and is only worth 10mb in filesize so not worth it IMHO...
Tommy Carrot
12th July 2015, 16:55
Can I get any ideas on Audio? I am thinking of downmixing them all to Stereo, since 5.1 is useless for TV episodes except for very rare occasions (action like 24) and I am 99% watching these either on the TV (2 speakers) or with headphones.
However what codec and bitrate should I use? My tests were done with HE-AAC at 128kbps , are there any thoughts on this?
Use LC-AAC instead. HE-AAC was created as a low bitrate codec, part of the audio is synthetized from a few parameters instead of properly coded, so while it's better at low bitrates, it's useless for high quality audio. I wouldn't use HE-AAC over 80 kbps.
PS: At Medium I get like 25fps average on 720p and 14fps on 1080p , is this optimal? I think next level (slow) drops massively in speed and is only worth 10mb in filesize so not worth it IMHO...
While slow may sometimes even increase the filesize, I've found it to be better in terms of quality than medium.
Check this screenshot comparison : http://screenshotcomparison.com/comparison/134912
First one is medium, mouse over is slow (CRF 21). Look for instance for distortions/noise near the hair on the right of the picture with preset medium.
benwaggoner
14th July 2015, 16:54
While slow may sometimes even increase the filesize, I've found it to be better in terms of quality than medium.
Yeah, better analysis can find more details worth preserving. I find slow the fastest preset worth using in offline.
-Ben Waggoner (via TapaTalk)
vBulletin® v3.8.11, Copyright ©2000-2024, vBulletin Solutions Inc.