X264 1 pass bitrates

[africanmarty]

hey u guys had a look with search function, but most threads regarding bitrates were for 2 pass encodes with filters added, however i was just wanted to know what bitrates were commonly used for the x264 codec when using a single pass encode with no filters or fancy busness, where the sourse resolution will be used for the output resolution and the source being good quality. what bitrates would you use for

480/576 (i or p)
720p
HDV/ 1080i
1080p

for a single pass in x264.

hope to hear from yous soon, regards Marty.

[tph]

Use crf for 1-pass encodes instead of a fixed bitrate.

[africanmarty]

what crf value would you use ?? i would like to know what bitrates some users would use for those resolutions too.

[Chengbin]

Try it yourself.

Start at a high CRF value, like 26, and keep going down until you find the highest one that you find that still gives you acceptable quality.

[LoRd_MuldeR]

26 may be a bit too high. I'd start with ~20 and increase the CRF in steps of 1, until you found the highest possible value that still gives satisfactory quality for your eyes.

If you need to limit the maximum bitrate, you must use VBV. Also note that changing other parameters will change the CRF meaning. Furthermore CRF was re-defined several times in the past.

So the same CRF value will only give (roughly) similar quality for different sources, if you use the same settings and the same revision of x264...

[Chengbin]

We went the opposite way! I went down, you go up!

Well, either way is fine.

[Sagekilla]

It usually tends to be easier to work with very high quality and work towards lower quality. More often than not you'll like the higher bitrate encode (naturally) and you'll be tempted to decrease your crf again.

Of course there will be some point when you don't see any significant improvements, but whatever method you use just find the best quality-size trade off you're willing to accept. My idea of quality is not the same as yours or anyone else, so the recommended method is to find the crf you like best when starting from the generally agreed level of transparency (18 - 20, depending on who you ask).

[Blue_MiSfit]

Also, if you plan to use hardware decoding (aka DXVA), make sure to enable VBV. It's relatively safe to use CRF and VBV together now, so no harm in doing so :)

I usually end up around CRF 18 for degrained / clean sources, maybe a little higher for untouched stuff. I rarely go higher than 20, and rarely go lower than 16, except for mastering purposes where I usually use 4-6 depending on my mood :D

~MiSfit