This feature is only from 2021.1 onwards.
VCU decoder output buffer vertical alignment of active video can be adjusted provided that actual buffer height is sufficient enough for adjustment.
Example, If Decoder gets 720x240 resolution video as input, then actual output video buffer resolution will be 736x256 (considering 32x alignment). A new configuration parameter called "output-position=<x,y>" is added to the decoder from 2021.1 onwards,.The x and y parameters decide the position of active video data in the buffer.
If output-position is set to <0,1> , that means the top-line in the video buffer will be skipped and active video data will be written from 2nd line onwards.
Sample control-sw and gstreamer pipelines: are as follows:
gst-launch-1.0 filesrc location=test_input.avc ! h264parse ! omxh264dec
output-position="<0,2>" ! filesink
ctrlsw-decoder -in test_input.avc -avc -o test_output.yuv --output-position