recomended CRF for backing up HD?

[saint-francis]

I have begun to tinker with backing up 1080p content with MeGUI using x264 and CRF and I set the CRF to 18 as I usually do for a DVD. Well that didn't cut the mustard. It gave me a file that was clearly to small. I downsized the resolution to 720 and the resulting file was 2.6 GB. Too small by about 2 or 3 GB right? The original file was a whopping 18 GB. So what's a good recommended CRF for backing up HD content to 720p? 12? 14? :confused:

[burfadel]

Well first of all, what other settings did you use for it? The second thing to keep in mind is its a constant quality mode, so it only uses the bitrate needed. If the original file was in Mpeg2, and the encoded file is in x264, then 2.6Gb can't really be classified as too small. You said you downsized it to 720P as well, I'd say its about right! It defeats the purpose if you're wanting the file to be the same size as the original, in terms of file size/resolution ratio. Is there a reason why you reduced the resolution ot 720P from 1080P? If your only intention is to fit in onto a DVD, then a 2-pass (at least) ABR mode would be more suitable.

[gigah72]

like said before, with allways the same encoding settings, the resulting filesize depends only on the source material.
i get resulting x.264/avc filesizes from ~ 850mb (Reservoir Dogs) to ~ 2500mb (PI), with same filtering, encodersettings, etc., only little difference in cropping ;) (both movies have more or less the same length and where Reservoir Dogs has more pixels)

[Atak_Snajpera]

If you are going to save encoded movies on DVD I suggest to use 2-pass mode.

[check]

It gave me a file that was clearly to small.When using CRF, stop caring about filesize! The entire point of crf is that you care about the output quality, not size.
If you find you want to control filesize, use 2pass, or change your thinking :p

[Dark Shikari]

If you are going to save encoded movies on DVD I suggest to use 2-pass mode.
I agree; if you're saving HD movies on DVD, you're limited to a specific filesize, and any less than that is useless.

On the other hand, if you're saving them on a hard disk to randomly access, I would never use anything except CRF.

[saint-francis]

I resized it because my projector is only 720p. And I really am just dabbling with this. Trying to test the HD backup waters. The source is Mpeg2. And I am going to use CRF. I am not that concerned about the size. I just thought that going from 18 GB to 2.6 was a little drastic. I just modified the HQ insane profile to constant quality and set the crf to 18. I didn't know if one needed to set a lower CRF when backing up files with such high bitrates.

[saint-francis]

I am now backing up the same video to 1080p with crf 16 and it's about 8.6 GB. I also tried backing it up to 1080p with crf 18 and it was 6. some GB. At crf 18 I was somewhat displeased with the quality. It was still very nice but not quite what I expected. So my question still remains. What crf are people generally using for high quality x264 encodings of 1080p? I'm just looking for some people's experiences and preferences. I'm not planning on burning this to DVD. And I know that when using crf I shouldn't be concerned with file size, etc. etc. But if I were totally unconcerned with file size I wouldn't be encoding them with x264. I'd just leave them the way they are. Reducing file size is the name of the game. Right? :confused:

[deets]

why not just do some tests and find a level your happy with :)

bung trim into your avisynth for 15 mins or something to save time encoding and compare different levels until you find something your happy with.

i know your looking for something a little more set, i was as well when i came from things like GK for xvid, but just best to find something your happy with as we all could say something different :P

it all depends on how your storing them, if you have a 120gb drive, space might be more of an issue, if you have 500gb then its less of a concern, crf is just about quality :)

[Dark Shikari]

I am now backing up the same video to 1080p with crf 16 and it's about 8.6 GB. I also tried backing it up to 1080p with crf 18 and it was 6. some GB. At crf 18 I was somewhat displeased with the quality. It was still very nice but not quite what I expected. So my question still remains. What crf are people generally using for high quality x264 encodings of 1080p? I'm just looking for some people's experiences and preferences. I'm not planning on burning this to DVD. And I know that when using crf I shouldn't be concerned with file size, etc. etc. But if I were totally unconcerned with file size I wouldn't be encoding them with x264. I'd just leave them the way they are. Reducing file size is the name of the game. Right? :confused:
What kind of quality problems are you encountering?

If you're encountering blockiness in dark areas, use Adaptive Quantization, i.e. --aq-strength 0.5 or the like.

You can also use a denoiser--I have been able to get an average quantizer of 22.843 (so CRF 23 or so) with a 720p film at 650kbps (!!!!) through use of FFT3DGPU + MVTools denoising. In other words, by getting rid of grain, you can get similar size while lowering the CRF considerably.

[saint-francis]

At 720p the picture was fine with crf 18. At 1080p I noticed some strange lines around the edges of moving objects. Small (but definitely noticeable) horizontal lines around and penetrating into the boarders of moving people's clothing and vehicles. There was no noticeable blocking. So I don't think this is a job for aq. I have just resorted to feeding it more in the form of crf 16. But it l;ooks like the resulting file is going to be close to 10 GB. A big jump from 6.7. This is a time consuming process since each encode takes about 20 hours. I don't want to encode just a section because the problems I experienced on the 1080p crf 18 encoding were not present in all scenes.

[Dark Shikari]

At 70p the picture was fine with crf 18. At 1080p I noticed some strange lines around the edges of moving objects. Small (but definitely noticeable) horizontal lines around and penetrating into the boarders of moving people's clothing and vehicles. There was no noticeable blocking. So I don't think this is a job for aq. I have just resorted to feeding it more in the form of crf 16. But it l;ooks like the resulting file is going to be close to 10 GB. A big jump from 6.7. This is a time consuming process since each encode takes about 20 hours. I don't want to encode just a section because the problems I experienced on the 1080p crf 18 encoding were not present in all scenes.
Horizantal lines? That sounds more like a bug than a quality issue. Can you post a sample of the video with that problem, or a screenshot?

[Selur]

sounds like interlacing ;)

[saint-francis]

sounds like interlacing ;)

This was my first assessment too. The lines look like such artifacts. And to top it off this is a tv rip. But, I am certain that no such artifacts are visible on the original material and MeGUI decides that the source is progressive. I can't post a screen shot right now because my workstation is tied up with this encoding and I can't even get the file to play on my laptop. I'll post one tomorrow.

[saint-francis]

Please forget about the lines. On a fresh installation of XP the lines are gone. :confused: I'm still learning the ins and outs of how to work with MPC so I assume the problem was something I did whilst tinkering with it. Thanks for all of your help everyone.