Convert x264 to x265 ?

[Nico8583]

Hi,

I have a movies collection, all encoded by me from Blu ray to x264 CRF 18 and I would like to try to convert 1 or 2 movies into x265 in order to know if there is an interest for me to convert all my movies.

Are there importants parameters to use to convert x264 to x265 ?

My x264 parameters are simples :
"Movie.avs" --preset slower --tune film --profile high --level 4.1 --crf 18 --open-gop --keyint 24 --qpfile "Chapters.qpfile" --output "Out.264"

Thank you !

[Jamaika]

Originally Posted by Nico8583

... is an interest for me to convert all my movies.

The interest isn't for you. This is useful for files RAW, DNG, ProRes.

Originally Posted by Nico8583

My x264 parameters are simples :
"Movie.avs" --preset slower --tune film --profile high --level 4.1 --crf 18 --open-gop --keyint 24 --qpfile "Chapters.qpfile" --output "Out.264"

Little information. How is size frame, bitrate?
For FullHD you can convert with min. bitrate 4500. It can't be too high dynamics of the film. The video with depth 8bit can has banding. Not all players work with 'open-gop'.

[littlepox]

As far as I can recommend:

1. Re-encode will always worsen the quality unless you enable --lossless, which in this case, you won't. If you wish to try, get the blu-rays back again and re-encode from them.

2. The parameters you were using for x264 are good enough; the only suggestion is that you should make --keyint much bigger, say 250(default by x264). --keyint 24 is for blu-ray disc compatibility(say, you are making blu-ray discs to be played on your PS3) and NOT for re-encode. Setting it too small results in a big reduction in efficiency.

3. Currently, x265 is doing extremely bad @ high quality. It does gain some advantage in low bit-rate settings, where all you care is whether you can still watch it without saying "am I watching a video recorded by a ten-years-old handphone?". And if you care a bit of the quality, you'll get disappointed by the washed output, with all details and film-grains gone. If you are expecting a similar quality to your x264 products, I'd suggest not to waste your time.

[Nico8583]

Interest for me is not quality but file size with an equal quality.

Size frame is Full HD, bitrate is give by CRF 18. Movies are played on PC or Android.

[littlepox]

If the "equal quality" means the quality is equal to x264, crf=18
then you'll probably need 200%~300% of the bitrate for x265.
If you are encoding with x264, crf=28
then switching to x265 gives you a discount in size without sacrificing the quality.

[Nico8583]

Thank you

1. It's too long to rip BD again, so I would like to use x264

2. It's not the subject but what is the impact of keyint ? Efficiency with quality or file size ?

3. Ok it's clear I want quality so x265 should not be a good way for me

[littlepox]

Keyint determines the maximum distance between two IDR frames.

An IDR frame is an independently encoded frame; the encoder must encode it without referencing to other frames. It's usually used at the beginning of a new scene, where the 1st frame has nothing to do with the previous scene. And its following, similar frames can refer to it; only the differences will be captured when encoding subsequent frames.

When you encode an IDR frame, it's bit-rate expensive: Having zero information from other frames is a penalty at encoding, while allowing longer distance lets the encoder enjoy the benefit by setting more frames to be non-IDR, and those frames can be encoded in higher efficiency.

x264 sets the default value to be 250. on a 25fps movie, it means two IDR frames can be at most 10 seconds away (it can be smaller than 10 seconds, x264 will judge it properly, so it's possible two IDR-frames are very close if scenes change very quickly).

If you set it to 24, that means every second there must be an IDR-frame. Do you expect your movie to change the scene every one second? If not, IDR frames inserted by compulsory limit does a harm to the encoding efficiency. On blu-ray discs this is not a serious problem, as they have enough spaces to waste. But is it true for your hard drive?

[Nico8583]

Ok thank you for these informations.
So a low value increase file size but don't affect quality ?
I'll made a test to compare file size between 240 and 24 keyint, I'm curious :-D

[birdie]

Originally Posted by Nico8583

Hi,

I have a movies collection, all encoded by me from Blu ray to x264 CRF 18 and I would like to try to convert 1 or 2 movies into x265 in order to know if there is an interest for me to convert all my movies.

Are there importants parameters to use to convert x264 to x265 ?

You won't gain anything by using x265 if you want the same picture quality as x264 at CRF 18. None. Just forget about this altogether.

[Nico8583]

I believed x265 was more efficient in file size with the same quality, fortunelaty I've asked to you

[birdie]

Believe what you want but there are hundreds of screenshots posted at these forums which show that at least for high-quality high-bitrate encodes x265 is actually worse than x264.

I didn't mean to laugh and I don't understand your stance.

[foxyshadis]

It's more efficient (but much slower) at lower bitrates, the lower the better. It requires a lot of argument tweaking at high bitrates just to match x264 and can't really exceed it (because fine film grain is impossible to compress much better). If you're looking for small files without much grain, you're its target market.

x265 --preset medium or --preset slow is probably all you need, but if you can live with slower, that's fine. Note, it's --tune grain not --tune film; x265 doesn't exactly match x264. Don't bother with --keyint, the only reason to reduce it is for faster random seeking (at a cost of a few % of size) or bluray compat (obviously impossible right now), otherwise x265 will place keyframes optimally as it is. Do NOT set --profile high unless you know why; main and main10 are equal to AVC's high and high10. Likewise, do NOT set level or open-gop. x265 will figure out the minimum level for you, probably 4 instead of 4.1, so you'd be unnecessarily restricting playback.

You can denoise, encode, and then use your player to create random noise, to save even more bitrate.

Sometimes I feel like I'm one of the few people at Doom9 who doesn't want perfect reconstruction of grainy movies. There's a place for that, but a lot of people here are unnecessary down on something that wasn't really made for their needs, and actively try to dissuade people with other needs from using it.

[ARRYMatie]

I don't like grainy movies either but with x265 unless you really up the grain, there'll be noticeable banding in certain areas (mainly darkish ones).

[Nico8583]

I give up my idea, I didn't know all this, thank you for the informations and advices

[Nico8583]

Just an information for x264.

I have made a test with keyint 24 and keyint 240, same movie, same source, CRF 18.

File size with keyint 24 : 12.1 GB
File size with keyint 240 : 11.5 GB

So for this movie, difference is 600 MB so about 5%.

I'll made a test with an other movie to see.

[littlepox]

Should you are interested, you can set keyint=0. 0 means unlimited distance and x264 will insert IDR frames purely based on scene change.

[Slitheen]

I did what the OP wanted to do. Reencoded some x264 encodes into x265.

The result was about half the size or less of the x264 file and the quality of the x265 file was about the same, certainly good enough.

There you go...

[Metaphor]

^^ Its hard to make such generalizations about quality, because all of our environments are different.

For you it may seem that viewing x265 on a 24" TN LCD might seem like you get comparable quality, while others here are comparing the most minute detail degradation because they are concerned about vieing on a 160" projection screen or having archival quality or are talking about the academics of compression.

For many casual users who like to tinker with compression, x265 is starting to gain traction (slowly). For the hard core and pedantic compression guru's you will still often hear of how far x265 has to go.

Neither are incorrect, mind you.

I'm using x265 myself and willing to accept the compromise that matches my needs. I want good quality, 10bpc, and am willing to use a higher CRF and dont really care than I'm not getting "some promised 50% bitrate savings" and even if in still frame analysis there is an advantage in x264 (sharpness, Edge detail, etc) I dont see it in enough to dissuade its usage my real world environment (from Monitors to 75" Displays).

So I'm happy enough to use it for my library, as well. We just cant say that its good enough for everyone yet, as it will only be good enough for everyone, once everyone decides that for themselves.

[blublub]

Hi, just a quick question if I am understanding thuys correctly:

If I used to do high quality encodes with CRF 17 under x264 there is no reason to switch to x265 (v 1.8) and use CRF 18-20 even if the resulting file size is a little smaller because x265 looses on detail in most film content on usual bluray movies.

Correct?

[Sharc]

Maybe it has been said already:
If you re-encode an x264 file with x265 you will always introduce additional losses whatever you select the settings of x265. You re-encode a lossy source with another lossy encode, so in very best case you get "almost same" quality as the x264 "original".