[x265] Bitrate calculation is off by 5:1 for FullHD video

[Steve Borho]

On Tue, Feb 18, 2014 at 6:55 AM, Mario *LigH* Rohkrämer <contact at ligh.de>wrote:

> Just the last 2 examples of encoding 60 seconds from ToS in 1080p:
>
> a) CRF 24 => 11402140 B * 8 b/B : 60 s = 1520.3 kbps (x265 reports 7597.54
> in CSV)
> b) CRF 18 => 26700793 B * 8 b/B : 60 s = 3560.1 kbps (x265 reports
> 17796.64 in CSV)
>
> It seems that x265 reports about 5x the bitrate of the result, but only
> for this large video dimension.
>
> Another test with a small video dimension (640x272) hits the bitrate
> rather correctly:
>
> c) fast: 709078 B * 8 b/B : 52.208 s = 108.6 kbps (x265 reports 107.87 in
> CSV)
> d) ultrafast: 5325541 B * 8 b/B : 52.208 s = 816.0 kbps (x265 reports
> 815.27 in CSV)
>
> CSV logs are available on request.


I'm a bit confused by which numbers you are comparing.  Are you using
frame-by-frame CSV or just the single-line-per-run CSV?  And are you
comparing the file size or the theoretical size?

-- 
Steve Borho
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