Miscellaneous video tuning parameters

CABAC: Applies only to H.264, and only when the Profile parameter is set to Main or High. This parameter enables arithmetic coding and can compress the same data with approximately 15% fewer bits. As a result, encoding is more efficient. There is no impact on video quality.

Recommendation: Always enable this parameter unless the intended decoder or playback device doesn't support it.

Density vs Quality: Applies only to H.264 and H.265. This parameter sets the balance between density on the appliance and video quality.

Note that this parameter controls density and quality, even though the parameter name in the XML is svq (speed vs quality).

Recommendation: On newer appliance models (L8xx and later), we recommend that you leave the default. On older appliance models, a different value might change the balance. However, never use -2 or -3 with H.265.

Lookahead: Lookahead indicates that the encoder should analyze a few frames into the future of the currently encoded frame, to allow the encoder to take future frame data into account during rate control logic. For example, if future frames are more complex, the encoder can allocate fewer bits to encode the current frame. In this way, the unused bits can be used to encode those future frames.

The tradeoff of a higher lookahead is that processing and latency increase slightly, to allow the encoder to analyze those future frames.

Recommendation: Set to Medium unless latency is critical.

Profile: Applies only to H.264 and H.265. For H.264, the profile affects video quality. For H.265, the profile sets various characteristics of the video.

Recommendation: With H.264, use High Profile to achieve higher video quality.

Slices: Applies only to H.264 and H.265. This parameter improves speed of encoding. Using a higher number of slices can improve speed optimization. However, this results in slightly lower video quality.

Recommendation:

Set to Auto so that the encoder uses a value appropriate to the image height (resolution). The following table specifies which value the encoder will assign when you choose Auto, based on the image height.