hi_venc_h264_vbr_param

Description

Defines the advanced VBR parameters of an H.264 encoding channel.

Prototype

hi_venc_h264_vbr_param = {"chg_pos": chg_pos,
                          "max_i_proportion": max_i_proportion,
                          "min_i_proportion": min_i_proportion,
                          "max_reencode_times": max_reencode_times,
                          "qpmap_en": qpmap_en,
                          "max_qp": max_qp,
                          "min_qp": min_qp,
                          "max_i_qp": max_i_qp,
                          "min_i_qp": min_i_qp}

Members

max_qp and min_qp are used to control the picture quality range, max_bit_rate is used to limit the maximum encoding bit rate within the bit rate statistical period, and chg_pos is used to control the bit rate base line for starting QP adjustment.

When the encoding bit rate is greater than max_bit_rate x chg_pos, the QP value of the image is adjusted towards max_qp. If the QP value reaches max_qp, the QP value is clamped at the maximum value and max_bit_rate does not take effect. In this case, the encoding bit rate may exceed max_bit_rate.
When the encoding bit rate is less than max_bit_rate x chg_pos, the QP value of the image is adjusted towards min_qp. If the QP value reaches min_qp, the encoding bit rate reaches the maximum value and the image quality is the best.

max_bit_rate is a member variable in hi_venc_chn_attr["rc_attr"] and is set during VENC channel creation.

Member	Description
chg_pos	Int, proportion of the bit rate when the QP value starts to be adjusted in VBR mode to the maximum bit rate. Value range: [50, 100] Default value: 90
min_i_proportion	Int, reserved.
max_i_proportion	Maximum ratio of bits allocated to I-frames and P-frames. Value range: [1, 100] The default value is 100.
max_reencode_times	Int, number of times that each frame is re-encoded. If set to 0, disables re-encoding. Value range: [0, 3] Default value: 2
qpmap_en	Int, reserved.
max_qp	Int, maximum QP value of P and B-frames. Value range: [0, 51] Default value: 51
min_qp	Int, minimum QP value of P- and B-frames. Value range: [0, max_qp] Default value: 24
max_i_qp	Int, maximum QP value of an I-frame. Value range: [0, 51] Default value: 51
min_i_qp	Int, minimum QP value of an I-frame. Value range: [0, max_i_qp] Default value: 24

Parent topic: Video/Image Encoding