What data rate for blu-rays to MP4 with ripbot264?

[David97]

I've been using ripbot264 constant rate of 15000 2 Pass on blu-rays and orginal rez and i can see no differance in it from the orginal blu-rays.

It makes the file size half of what it was. I was wondering what you guys use?

Im playing them on a 40" and 52" 1080p LCDs off my HTPC.

[Atak_Snajpera]

Normal guys would use CRF@22. Period. Normal guys do not use 2-pass because you cannot predict how much data each movie requires. 2-pass use ONLY if you want exact size!!! Also I would use MKV instead of MP4! (MP4 does not support FLAC compression for instance)

[David97]

Originally Posted by Atak_Snajpera

Normal guys would use CRF@22. Period. Normal guys do not use 2-pass because you cannot predict how much data each movie requires. 2-pass use ONLY if you want exact size!!! Also I would use MKV instead of MP4! (MP4 does not support FLAC compression for instance)

Im not much of a audio buff for movies.

Why CRF22? What data rate does that end up being or is it differant for every movie? I don't want to lose any quality of the blu-ray it defeats the whole purpose if you do.

I used MP4 since most anything will play it by default. I tired MKV seen know differance, i think file size was alittle smaller in MP4.

[Atak_Snajpera]

Why CRF22? What data rate does that end up being or is it differant for every movie? I don't want to lose any quality of the blu-ray it defeats the whole purpose if you do.

By compressing already compressed material you WILL always loose quality! Why CRF22? Because this is compromise between quality and size. If you are not satisfied use 20 or lower. Constant Quality mode will adjust bitrate automatically according to content of movie. It is almost imposible to predict final bitrate/size. However for full movies 1920x1080 resolution you can expect bitrates between 10-12Mbps. No need to waste time for extra pass.

I used MP4 since most anything will play it by default. I tired MKV seen know differance, i think file size was alittle smaller in MP4.

You have HTPC so mkv is not a problem.

[nurbs]

You will always lose quality when you reencode (with a lossy codec). The question is if the loss is noticable and CRF encoding is a good way to ensure the movie gets enough bitrate and you are not wasting space. Encode a couple of short samples and find a CRF that looks good to you. Personally I use 22 for 1080p, 21 for 720p and 20 for SD, but it comes down to personal preference. 22 is a good starting value. The resulting bitrate will be different for every movie depending on resolution, the complexity of the source material and the encoding options you use. CRF tries to provide an easy way to make encodes with constant quality (for fixed encoding options) without you having to worry about bitrate.

The container (MP4/MKV) doesn't make much difference other than slightly different overhead and what kind of tracks you can stick into it. MKV offers more choice for audio and subtitles, but MP4 has better compatibility with standalone players, mostly handhelds and consoles. I use the latter for that reason.

edit:
Also double posting is against the forum rules and you already got the same answer in your other thread.

[LoRd_MuldeR]

Originally Posted by David97

Why CRF22? What data rate does that end up being or is it differant for every movie?

Yes, the bitrate will be different for every movie, because every movie is different! CRF uses as many bits as required for the individual movie.

Also you should treat CRF=22 as a starting point to find your own CRF. After all you must find the highest possible CRF value that still gives accaptble quality for your eyes!

I personally tend to use CRF=20 now with MB-Tree enabled...

[David97]

Thanks for the info. Is there a way to set the bitrate and not have ripbot do 2 passes?

[LoRd_MuldeR]

Originally Posted by David97

Thanks for the info. Is there a way to set the bitrate and not have ripbot do 2 passes?

Single-Pass ABR really is not recommended. Two-Pass mode is intended to hit a desired (average) bitrate with maximum quality and you should use it

If you want to hit a certain level of quality without a size/bitrate restriction, then you should use Single-Pass CRF mode...

[David97]

Originally Posted by LoRd_MuldeR

Single-Pass ABR really is not recommended. Two-Pass mode is intended to hit a desired (average) bitrate with maximum quality and you should use it

If you want to hit a certain level of quality without a size/bitrate restriction, then you should use Single-Pass CRF mode...

I gave CRF a try and the rates where all over the place.

One clip was 18mbps used CRF 19 it came out at 15mbps that was fine and looked great.

Another clip was 18mbps as well i used CRF 19 and it came out at 10mbps and did not look very good. I guess ripbot figured 10 was anough? How does it come to that conclusion?

I would like to go know lower than 15mbps on every movie.

[LoRd_MuldeR]

Originally Posted by David97

I gave CRF a try and the rates where all over the place.

One clip was 18mbps used CRF 19 it came out at 15mbps that was fine and looked great.

Another clip was 18mbps as well i used CRF 19 and it came out at 10mbps and did not look very good.

I would like to go know lower than 15mbps on every movie.

Again: The bitrate that CRF will produce is totally unpredictable, because it highly depends on the content.

However if one movie looks good at a specific CRF value, all other movies (of similar nature) will give similar quality at that CRF value - given you also use identical settings.

Any movie will use the bitrate it requires to get the desired quality. That's the "magic" of CRF

(If you don't want quality-based encoding, as CRF mode does, you will have to use 2-Pass mode and set the desire target average bitrate)

Originally Posted by David97

I guess ripbot figured 10 was anough? How does it come to that conclusion?

RipBot264 doesn't conculde anything. It tells x264 to use the CRF value you have selected and that's it.

All the rate control happens inside x264