Wrong size computation in H.264

shyaki

Fri, 09/28/2007 - 09:09

the size of the image is computed by Intel like this

lpInfo->info.clip_info.height = sps->frame_height_in_mbs * 16-

(4>>sps->frame_mbs_only_flag)*(sps->frame_cropping_rect_top_offset +

sps->frame_cropping_rect_bottom_offset);

for 1920*1088i,

sps->frame_height_in_mbs = 68

sps->frame_mbs_only_flag =0

sps->frame_cropping_rect_top_offset =0

sps->frame_cropping_rect_bottom_offset =4

The above computation g ives the height of 1072 instead of 1080.

4>>sps->frame_mbs_only_flag seems to be

2>>sps->frame_mbs_only_flag

since there are two fileds in a frame.

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vladimir-dudnik (Intel)

Mon, 10/01/2007 - 13:01

thanks for catching this, we will fix that in the next version.

Regards,
Vladimir

shyaki

Tue, 10/02/2007 - 07:10

Correct computation should be like this:

crop_left = SubWidthC[p->chroma_format_idc] * p->frame_cropping_rect_left_offset;

crop_right = SubWidthC[p->chroma_format_idc] * p->frame_cropping_rect_right_offset;

crop_top = SubHeightC[p->chroma_format_idc]*( 2 - p->frame_mbs_only_flag ) * p->frame_cropping_rect_top_offset;

crop_bottom = SubHeightC[p->chroma_format_idc]*( 2 - p->frame_mbs_only_flag ) * p->frame_cropping_rect_bottom_offset;

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