Group of Pictures Parameters - 2020.2 English

H.264/H.265 Video Codec Unit v1.2 Solutions LogiCORE IP Product Guide (PG252)

Document ID: PG252
Release Date: 2020-11-24
Version: 2020.2 English

Table 1. Encoder GOP Section Parameters
Parameter	Description and Possible Values
GopCtrlMode	Specifies the Group Of Pictures configuration mode. Allowed values: DEFAULT_GOP: IBBPBBP... (Display order) LOW_DELAY_P: GopPattern with a single I-picture at the beginning followed with P-pictures only. Each P-picture uses the picture just before as reference. IPPPP…. LOW_DELAY_B: GopPattern with a single I-picture at the beginning followed with B-pictures only. Each B-picture use the picture just before as first reference; the second reference depends on the Gop.Length parameter. IBBB…. PYRAMIDAL_GOP: Advanced GOP pattern with hierarchical B-frame. The size of the hierarchy depends on the Gop.NumB parameter. ADAPTIVE_GOP: The encoder adapts the number of B-frames used in the GOP pattern based on heuristics on the video content. DEFAULT_GOP_B: IBBBBBB... (P frames replaced with B). PYRAMIDAL_GOP_B: Advanced GOP pattern with hierarchical B frame. Here, P-frames are replaced with B.
Gop.Length	GOP length in frames including the I-picture. Used only when GopCtrlMode is set to DEFAULT_GOP. Should be set to 0 for Intra-only. Range: 0–1,000. Default value: 30
Gop.FreqIDR	Specifies the minimum number of frames between two IDR pictures (AVC and HEVC). IDR insertion depends on the position of the GOP boundary. Allowed values: positive integer or -1 to disable IDR region. Default value: -1
Gop.FreqLT	Specifies the long term reference picture refresh frequency in number of frames. Allowed values: positive integer or 0 to disable use of Long term reference picture Default value: 0
Gop.NumB	Maximum number of consecutive B-frames in a GOP. Used only when GopCtrlMode is set to DEFAULT_GOP or PYRAMIDAL_GOP. Allowed values: When GopCtrlMode is set to DEFAULT_GOP, Gop.NumB shall be in range 0 to 4. When GopCtrlMode is set to PYRAMIDAL_GOP, Gop.NumB shall take 3, 5, 7, and 15.
Gop.GdrMode¹	When GopCtrlMode is set to LOW_DELAY_P or LOW_DELAY_B this parameter specifies whether a Gradual Decoder Refresh (GDR) scheme should be used or not. When GDR is enabled, the Gop.Length specifies the frequency at which the refresh pattern should happen. To allow full picture refreshing, this parameter should be greater than the number of CTB/MB rows (GDR_HORIZONTAL) or columns (GDR_VERTICAL). DISABLE: no GDR GDR_VERTICAL: Gradual refresh using a vertical bar moving from left to right. GDR_HORIZONTAL: Gradual refresh using a horizontal bar moving from top to bottom. Default value: DISABLE Note: When GDR is enabled, the Gop.FreqIDR specifies the frequency at which the refresh pattern should happen. To allow full picture refreshing, this parameter should be greater than the number of CTB/MB rows (GDR_HORIZONTAL) or columns (GDR_VERTICAL).
Gop.EnableLT	Enables/Disables long term reference picture support Allowed Values: TRUE/FALSE Default value: FALSE
Gop.FreqLT	Specifies the frequency of LTR pictures in GOP. Default value: 0
Gop.TempDQP	Specifies a Delta QP for pictures with temporal-ID 1 to 4 Default value: 0 0 0 0
When GDR is enabled,, the GOP.FreqIDR specifies the frequency at which the refresh pattern should occur. To allow the full picture to refresh, this parameter should be set to a value greater than the number of CTB/MB rows (GDR_HORIZONTAL) or columns (GDR_VERTICAL).