Documentation

acl.himpi.venc_create_chn

C Prototype

hi_s32 hi_mpi_venc_create_chn(hi_venc_chn chn, const hi_venc_chn_attr *attr);

Python Function

ret = acl.himpi.venc_create_chn(chn, attr)

Function Usage

Creates an encoding channel.

The Atlas 200/300/500 Inference Product does not support this API in the current version.

The Atlas Training Series Product does not support this API in the current version.

Input Description
chn: int, encoding channel ID.

attr: dict, dictionary of the encoding channel attributes. For details, see hi_venc_chn_attr.

Return Value

ret: int, error code.

Restrictions
  • The channel ID of a single device must not be greater than the maximum channel ID.
  • An encoding channel has the encoder attributes, RC attributes, and group of pictures (GOP) attributes.
  • In the encoder attributes, the stream buffer depth, stream fetching mode, and encoding profile must be set according to Table 1.
  • The recommended encoding sizes are 3840 x 2160 (4K), 1920 x 1080 (1080p), and 1280 x 720 (720p).
  • For H.264/H.265 encoding, a frame buffer consists of YHeaderSize, CHeaderSize, YSize, CSize, PmeSize, PmeInfoSize, and TmvSize. The encoder calculates the buffer allocation based on the maximum width and height by default. When configuring the channel width and height, ensure that each frame buffer calculated based on the channel width and height is within that calculated based on the maximum channel width and height.
  • The input/output frame rate (src_frame_rate/dst_frame_rate) in the attributes of the bit rate controller is used to allocate the bit rate (bit_rate) during encoding, but not the final display frame rate of the player. For details about how to set the display frame rate, see acl.himpi.venc_set_h264_vui or acl.himpi.venc_set_h265_vui.

    You are advised to set the control frame rate to be the same as the display frame rate. Otherwise, the bit rate during playback may be different from the encoding bit rate configured by the user, and the playback bit rate will vary with the configured display frame rate.

References

Table 1 Restrictions on encoder attributes

Encode Protocol

Encode Mode

Stream Buffer Depth

Stream Fetching Mode

Encode Profile

H.264

Frame
  • When mini_buf_mode = 0: Buffer allocation ≥ max_pic_width x max_pic_height x 3/4
  • When mini_buf_mode = 1: Buffer allocation ≥ 32 x 1024 bytes

Frame/Slice

Baseline

Main Profile

High Profile

JPEG

Frame
  • If mini_buf_mode is set to 0 and the original image format is YUV420, the minimum buffer size is calculated as follows: Minimum buffer size = 16-aligned original image width x 16-aligned original image height x 3/2. If the original image format is YUV422 packed, the minimum buffer size is calculated as follows: Minimum buffer size = 16-aligned width of the original image x 16-aligned height of the original image x 2
  • When mini_buf_mode = 1: Buffer allocation ≥ 32 x 1024 bytes

Frame/Ecs

Baseline

H.265

Frame
  • When mini_buf_mode = 0: Buffer allocation ≥ max_pic_width x max_pic_height x 3/4
  • When mini_buf_mode = 1: Buffer allocation ≥ 32 x 1024 bytes

Frame/Slice

Main Profile

Main 10 Profile (not supported currently)
  • When mini_buf_mode = 0: Buffer allocation ≥ max_pic_width x max_pic_height x (3/4) x (5/4)
  • When mini_buf_mode = 1: Buffer allocation ≥ 32 x 1024 bytes

Frame/Slice

Main 10 profile (not supported currently)
Parent topic: VENC/JPEGE APIs