Determining the total number of motion vectors in an HEVC encoded video

[JamesLittle]

Hi everyone,
I have some HEVC encoded videos with the following encoding settings:

Resolution: 1280 x 720
Depth: 8
GoP size of: 4 (IBBB...)
Total number of encoded frames: 240

With this information, how can i determine the total number of possible motion vectors in a sequence.

Thanks for your help in advance

James

[Parabola]

If you have all 8x8 PUs and two vectors for each, the most motion vectors you can have in the sequence is:
1280/8*720/8*2*(number of B pictures)
It's very unlikely that an efficient encoder would encode real video with this many vectors though.

[JamesLittle]

Hi Parabola,

Thanks for the reply


James

[Shevach]

First of all you should know what's the minimal CU size. This value is derived from SPS (see the SPS param log2_min_luma_coding_block_size_minus3).
If all CTUs are split to the minimal CU and all CUs in turn are inter and each CU is split into 4 PUs and each PU is bi-predictional (pay the special attention to 4x8 and 8x4, since for these partitions bi-directional is forbidden) then the maximal number of MVs achieved.

For example, let's assume that the minimal CU is 16x16 and each CU is split into four 8x8 PUs then
the maximal number of MVs is ((Width × Height)/(16x16))×4x2.