Quants problem

[ZionDK]

I'm encoding some music videos at the moment at the sizes around width: 528 (FS) / 608 (WS), but no matter what I do the quants stay almost the same.

Source file: File size: 197 MB, play time: 3mn 57s, bitrate: 6963 Kbps, AR: 720x480 (not cropped).

After encode: At bitrate 1500 quants were like I24, P26, B28, but at 2500 they were only decreased to I20, P22, B24.

I'd like to end up around ~18. Is the only thing I can do to up the bitrate?

[check]

you can either increase the bitrate or the encoder quality settings.

[Dark Shikari]

From 26 to 22 isn't "almost the same." That's a huge difference, bitrate and quality-wise.

[ZionDK]

you can either increase the bitrate or the encoder quality settings.
Okay, thanks for clearing that out.

From 26 to 22 isn't "almost the same." That's a huge difference, bitrate and quality-wise.
Right, I just expected some drastic change.


Thanks both of you.

[ZionDK]

When doing these small encodes there's a big difference to the quants of wide screen videos and full screen, because more of the "video" is cut (black bars) on wide screen videos and therefore is the quants a lot smaller because there's a larger difference to source.

Is my hypothesis correct?

[foxyshadis]

Why not just encode to crf 18 if you want q18 average?

Once you do that, take a hard look at the differences between the 18, 22, and 26 videos. Be sure you really want to sacrifice the extra 60% more bitrate to get it down to 18.

[Dark Shikari]

Why not just encode to crf 18 if you want q18 average?

Once you do that, take a hard look at the differences between the 18, 22, and 26 videos. Be sure you really want to sacrifice the extra 60% more bitrate to get it down to 18.CRF 18 does not mean average quantizer 18.

[ZionDK]

CRF 18 does not mean average quantizer 18.
Than what does crf18 mean?

[check]

it means 'try to achieve the visual same quality as qp 18 in the smallest possible filesize'.

qp 18 means 'encode every p frame at quantizer 18, and base I and B frame quantizers on the ipratio and pbratio'.

[Dark Shikari]

it means 'try to achieve the visual same quality as qp 18 in the smallest possible filesize'.I'm pretty sure it doesn't mean this either.

Ratefactor correlates with QP, but there are cases in which CRF 18 can mean average QP 24, or it can mean average QP 16. It is entirely source-dependent.