Frame-Type Options

Advanced features for managing the frames in your output.

A significant number of options are exposed for defining the cadence of frames, within a decodable segment of time referred to as a GOP (Group of Pictures.) By default, output will have variable length GOPs optimized around detection of scene changes, with each GOP at least 25 frames in length between IDR frames.

It is possible to force fixed GOPs by setting keyint and keyint_min to the same number. This is frequently helpful when using adaptive bitrate packages so segments align. To disable non-IDR scenecut keyframes, you can also set sc_threshold to zero.

Parameter

Description

Allowed Values

Default Value

keyint_min

Specify the minimum distance between I-frames.

Positive Integer

25

level

As set of constraints that specify decoder performance for a profile.

Positive Integer

high profile, main profile, iphone_stream, roku: 30(3.0)
baseline profile: 13(1.3)

sc_threshold

Specify the sensitivity of x264's scenecut detection.

Positive Integer

40

bf

Specify the number of b-frames.

Positive Integer

16

b_strategy

Adaptively decides through a low-resolution lookahead the best number of B-frames.

0, 1, 2

1

coder

CABAC is the default entropy encoder used by x264.

0, 1

1(CABAC enabled)

refs

Specify how many references can be used, through a maximum of 16.

Positive Integer

6

flags

Enable or disable the loop filter.

-loop/+loop, -psnr/+psnr

+loop (Enabled)

deblockalpha, deblockbeta

One of H.264's main features is the in-loop deblocker, which avoids the problem of blocking artifacts disrupting motion estimation.

Positive Integer

0 (Must have '-flags +loop')

directpred

Specify the direct MV prediction mode.

0 — none,
1 — spatial
2 — temporal
3 — auto

main, high, baseline, smooth_streaming — 1,
roku — 3

aq-strength

Specify the amount of Adaptive Quantization(AQ) that is applied to the frames.

Positive float number
0.5 – low AQ
1.5 – strong AQ

1.0

force-cfr

Enable constant framerate.

1, 0

0

👍

For level parameter

Drop the decimal, for example 3.0 is 30, 1.3 is 13.