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Old 16th August 2015, 22:12   #564  |  Link
r0lZ
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Quote:
Originally Posted by Airmiles View Post
r0IZ, I use CRF 16 all the time, but with very different results in file size. Avatar ended up with 23,85GB, but Lion King ended up with only 5,14GB. With exactly the same settings. Now I know LK is 1:29h and Avatar is 2:42h, but even if you double the GB of LK, you still don't get to 23 GB, so what am I missing here?

I have 6TB of LaCie storage, so I am more worried about the quality of the LK file, then I am about the space that Avatar takes up, but some more explanation would help my future rip decisions.

Hope you can enlighten me on this.
The difference is that Avatar is a live movie, with many details and fast action scenes. Everything in that film is difficult to compress without losing quality.

In the other hand, the Lion King is traditional animation in the "ligne claire" style, with large areas of flat colour. That's extremely easy to compress, with only a small quality loss. That kind of traditional hand drawn animation is the best example of movies easy to encode with a low bitrate. Especially if the image is clean because it has been released digitally or if the movie has been restored and much of the noise (always difficult to encode) has already been filtered.

Between those two extremes, there is CGI animation (like the Pixar films), also easy to encode because the images are clean and without noise, but a little bit more difficult than traditional animation because there are less large flat areas.

In all cases, encoding in CRF mode gives an equivalent quality, but with very different bitrates.

BTW, it's one of the interests to use CRF instead of 2-pass. If you use the same CRF value for different films, you will always obtain a similar quality (dependent also, of course, of the quality of the source). When you encode in 2-pass, you may give a too low bitrate when you encode Avatar, and end up with a badly encoded movie, and you will almost certainly give a too high bitrate to Lion King, and obtain an excellent quality, but an unnecessarily big file. It's why IMO it is totally wrong to think that you must use a certain bitrate to obtain a good quality. The bitrate to use depends of the movie, and the CRF mode is smart enough to evaluate it for you, intelligently.

Again, IMO, 2-pass should be used only when encoding for a target file size, like when you want to put the MKV on a DVD-R.

And trust your eyes. Can you see badly encoded images in The Lion King (when playing back the film at the normal speed)? No? That means that 5 GB is enough for that movie.

(I have already explained recently in this thread why CRF gives very different bitrates like what you have observed, and why encoding in 2-pass is usually not a good idea. I'm too lazy to search the post now, but it was this summer, and you should find it easily if you need more info.)

[EDIT] I have not noticed page 29 of this thread, so I have typed this long reply. sneaker_ger has explained the same thing in one sentence!

Quote:
Originally Posted by Airmiles View Post
By the way, I did not see where BD3D2MK3D shows the estimated file size before ripping. Did I miss a button? Where does it show this?
When you encode in 2-pass or ABR AND with the option to specify the file size instead of the bitrate, BD3D2MK3D computes the bitrate after the demux operation and the audio and subtitle conversions (because it needs the to know the size of the final audio and subtitle files). It shows you the computed bitrate in the last dialog. The content of that dialog is also printed in the console and copied to the BD3D2MK3D.log file. Of course, you can also see the bitrate in the x264 command in _ENCODE.cmd.

When encoding in CBR mode, the bitrate doesn't need to be computed.
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Last edited by r0lZ; 16th August 2015 at 22:19.
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