tree 0308302876ae7e1eee40bf6cc0088c63c0b93025
parent 868dc9020299af117b0c58b63ccf89205ae32956
author Cheng Chen <chengchen@google.com> 1576024773 -0800
committer Cheng Chen <chengchen@google.com> 1576262541 +0000

Make rate_correction_factor support hierarchical structure.

Rate correction factor is used to estimate the required bits to
encode a frame.

The factor is determined by the factor of its nearest frame of the
same frame type. For example, if the frame is an internal arf, its
factor relies on the previous internal arf's factor.

Here we compute the rate correction factor for each layer separately,
and use the averaged value as the base for current frame's factor.

Let each encoding layer has its corresponding rate_correction_factor.
Previously, 4 different layers are supported: key frame, arf_std,
arf_low, inter_normal.
This change allows it to support 6 layers:
key frame, arf (layer 1), internal arf (layer 2 - 5).

Performance:
new_spd4  Avg_psnr ovr_psnr ssim  vmaf
Lowres    -0.11    -0.14    0.17  -0.45
Midres    -0.03    -0.09    0.37  -0.29
Hdres     -0.05    -0.08    0.20  -0.27
Ugc360p    0.01    -0.16    0.20  -0.25

new_spd2  Avg_psnr ovr_psnr ssim  vmaf
Lowres    -0.06    -0.10    0.17  -0.38
Midres    -0.04    -0.05    0.51  -0.22
Hdres      0.05     0.04    0.35  -0.07
Ugc360p    0.05    -0.09    0.32  -0.21

new_spd1  Avg_psnr ovr_psnr ssim  vmaf
Lowres    -0.19    -0.29   -0.07  -0.40
Midres    -0.16    -0.41    0.24  -0.63
Hdres (still running)
Ugc360p   -0.10    -0.43    0.03  -0.49

STATS_CHANGED

Change-Id: I78ee63a5162e21771e2290e137046899499e71fd