Encoding x264: Q16 through Q21 Ehk?

[Krajan]

Trying to reencode a 1080p MKV to MP4 using Xvid4PSP.
The original file is about 8.5Gig and I'd like to reduce file size, go down to 720p and I'll burn in SRT subtitle while at it...
The problem is that I obviously have no idea what preset I should use(!) :/
Q16 Turbo up to Q21 Ultra. What the heck does that mean?? (stop laughing! )

I just tried Q16 Medium - the output went 11.5Gig
Well it will take some time to try it again - so spare me the time by explaining how to do this the RIGHT way.
I can't open the MKV into GSpot to inspect it in forehand... but it said that the MP4 bitrate is 11177kbps (?)CBR(?)
Should I use another tool for this operation?

If an answer is too much to ask Please direct me to the neerest Well of high knowledge(!)

/Krajan

[poisondeathray]

You have to do 2-pass mode for an exact target size. (Push the "E" button beside video encoding)

CRF mode is constant quality, lower is better (but bigger filesize). It is faster than 2-pass encoding, but the ending filesize may vary wildly depending on the source

Turbo is faster/lower quality, Ultra is better, Extreme is the best. You can also adjust the presets if you want by pushing the "E"

To add subtitles, subtitles=> add

[Krajan]

DOH!
I must admit that I have been there and fibbled arround with those knobs before :/ But I must say I havn't seen the 2-pass size selection before.
There's now meaning having the a better quality rate than the original right?

- A follow up question is: what's the meaning of the AVC Level?

N thanks dude! U really made my day!

[poisondeathray]

A follow up question is: what's the meaning of the AVC Level?

Basically it is a specification, and sets limits according to the level. The higher the level the more parameters are allowed. Certain devices (e.g. IPOD, PS3, etc..) are limited to a "lower level" therefore lower quality settings

You can scroll down and see the chart:

http://en.wikipedia.org/wiki/H.264/MPEG-4_AVC

[RickA]

Greets,

As you have found out Gspot does not work too well on mkv's. Use MediaInfo instead. I'm partial to mkv's because they allow me to use AC3 DD for the audio with my HTPC. Plus I can easily mux in other audio tracks and subs after the encode with mkvmerge.

I like Xvid4PSP but have recently become very fond of RipBot264. A program you may wish to try if you have not already. Does away with the Turbo, Ultra, etc preset type selections. You can adjust the encoder settings if you wish in a profile option. RipBot can build in the subtitles for you if you like. I prefer to keep them selectable so I can turn them on / off during playback if I choose.

Recently there have been some nice changes to the way CRF works. I like it much better now. Due to these changes it is now supposedly understood to use a number or two higher than the old suggested defaults for an equiv quality encode at near same file sizes. Meaning the old norm of starting with CRF 18 to see if you feel it is transparent, you should now start with CRF 20 to see. I continue to use CRF 18 since that is the lowest RipBot selection allows. Many consider the old CRF18 as near transparent quality. Meaning your encode looks about the same as the source while still allowing you to compress the size a decent amount.

Remember your original encode is most likely already in a lossy format. So the closer you go towards lossless (like going to Q16 and below to Q0) you are going to 'decompress' it back to it's truer original source size and make it larger than your source file. Which is why you ended up with 11.5GB output when your source file is closer to 8.5GB.

Cheers,
Rick