The VideoLAN Forums

Hello all,

I don't understand why a movie or YouTube video has a certain bitrate (like 1100 kb/s or N/A) with a high level of quality. When I convert a video file, I find I need to use 1500-1800 kb/s bitrate, x264 "veryslow" preset, "fastdecoding" tuning selection, and "main" profile within the input/codecs to get at least a 99% identical quality for a higher disk-size. e.g: A 2 hour long movie will be 1.1GB. The converted with these settings will be 1.58-1.7GB. Its Ok but it could be better.

Any help to accomplish equal quality for fair disk-space would be appreciated. I'm hoping to get equal quality more/less down to the pixel.

Thanks.

When you reencode a video with a lossy codec like H.264, you always lose quality. It's a lossy to lossy conversion, it's obviously not lossless.
That said, your best bet is not to force a bitrate but to use the CRF value of x264, in VLC the setting is named Quality-based VBR in Tools -> Preferences -> Show settings: All -> Input/Codecs -> Video codecs -> x264. Limits are 18 and 28, the default is 23. Higher value = more compression.
Do not force the profile to Main either, but use High. And I suggest to use the Film tune setting, except if you're encoding anim.

I tried what you recommended, even set the CRF to 27. Its not 100% identical to the original, but I am pretty content. And the 2 hour movie is 1.03GB in size. Thank you.

Another question, After editing my videos, I like to render them in lossless, and in mkv format, so I can save the details. Then I convert it to mp4 in vlc. Can I get away with this, or is there a better solution?
Also, just out of curiosity, why is it not recommended to force Main as profile?

I like to render them in lossless

Sorry but I don't understand what you mean with "render in lossless".

why is it not recommended to force Main as profile?

Main has more restrictions that High. Long story short: Main is usually used for SD and High for HD.
https://en.wikipedia.org/wiki/Advanced_ ... g#Profiles

Sorry for being vague. Some video-editing softwares have quality presets, like low, medium, high. The highest is Lossless. I use this preset to render with, so I can save the quality/details. Though it makes file sizes ridiculously high. Does that clarify?

It's the best you can do for editing a file. But at the end when you compress with a lossy codec the process is not lossless.
It's like compressing a WAV file to MP3, the lossless WAV file is always much bigger than the lossy MP3, and the MP3 is missing details.