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.

ParameterDescriptionAllowed ValuesDefault Value
keyint_minSpecify the minimum distance between I-frames.Positive integer numbernone (automatically determined by codec)
levelAs set of constraints that specify decoder performance for a profile.Positive integer numberhigh profile, main profile, iphone_stream, roku: 30(3.0)
baseline profile: 13(1.3)
sc_thresholdSpecify the sensitivity of x264's scenecut detection.Positive integer number40
bfSpecify the number of b-frames.Positive integer number16
b_strategyAdaptively decides through a low-resolution lookahead the best number of B-frames.0, 1, 21
coderCABAC is the default entropy encoder used by x264.0, 11(CABAC enabled)
refsSpecify how many references can be used, through a maximum of 16.Positive integer number6
flagsEnable or disable the loop filter.-loop/+loop, -psnr/+psnr+loop (Enabled)
deblockalpha, deblockbetaOne of H.264's main features is the in-loop deblocker, which avoids the problem of blocking artifacts disrupting motion estimation.Positive integer number0 (Must have '-flags +loop')
directpredSpecify the direct MV prediction mode.0 — none,
1 — spatial
2 — temporal
3 — auto
main, high, baseline, smooth_streaming — 1,
roku — 3
aq-strengthSpecify the amount of Adaptive Quantization(AQ) that is applied to the frames.Positive float number
0.5 – low AQ
1.5 – strong AQ
force-cfrEnable constant framerate.1, 00


For level parameter

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