acl.himpi.vdec_create_chn

hi_s32 hi_mpi_vdec_create_chn(hi_vdec_chn chn, const hi_vdec_chn_attr *attr);

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

Creates a decoding channel based on the configured channel attributes.

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.

ret: int, error code.

• 0 indicates success.
• Other values: failure. For details, see Common Return Codes.

• The channel ID of a single device must not be greater than the maximum channel ID.
• Before this API call, ensure that a decoding channel has not been created yet or has been destroyed. Otherwise, a failure is returned.
• If the OS memory is insufficient, the error code HI_ERR_VDEC_NO_MEM is returned. In this case, you can expand the OS memory as needed.
• If the H.264 stream to be decoded has B-frames or the H.265 stream to be decoded supports temporal motion vector prediction (MVP) (sps_temporal_mvp_enabled_flag = 1), set temporal_mvp_en to 1 for the created channel and allocate VBs for the TMV output of each frame to avoid artifacts. The requested VB count of TMV output equals RefFrameNum plus 1. The TMV buffer size is much smaller than the image VB size, and can be queried by using the acl.himpi.vdec_get_tmv_buf_size call.
• For H.264 and H.265 decoding, the minimum VB allocation per decoding channel is the sum of the number of reference frames and the number of display frames plus 1. For JPEG decoding, the minimum VB allocation per decoding channel is the number of display frames plus 1. The requested VB allocation varies according to the decode protocol and can be queried by using the acl.himpi.vdec_get_pic_buf_size call.
• To skip decoding B-frames in H.264 streams or skip decoding H.265 streams with temporal MVP support (sps_temporal_mvp_enabled_flag = 1), set temporal_mvp_en to 0 for the created channel. In this case, no TMV information is output, and therefore you do not need to allocate a TMV VB pool, which saves memory.
• Set the requested frame VB size (frame_buf_size) and count (frame_buf_cnt) as well as the requested TMV VB size (tmv_buf_size) based on the stream to be decoded. The decoder allocates private VB pools based on these configurations.
• As long as the allocated frame buffer and TMV buffer are large enough, the decoding channel can decode a stream with any resolution in the valid range. The channel width and height are related only to the size of the stream buffer and SCD buffer.