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Fix rate allocation between temporal layers in SVC.

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Bitrate of three temporal layers as fraction of total bitrate
after fix:  0.54, 0.16, 0.30
before fix: 0.54, 0.30, 0.16

Bug: none
Change-Id: I8134abc19d5d6723b7a959196ca9c1635026eadc
Reviewed-on: https://webrtc-review.googlesource.com/66060
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Reviewed-by: Åsa Persson <asapersson@webrtc.org>
Reviewed-by: Michael Horowitz <mhoro@webrtc.org>
Commit-Queue: Sergey Silkin <ssilkin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22726}
This commit is contained in:
Sergey Silkin
2018-04-03 10:03:31 +02:00
committed by Commit Bot
parent f26abf827d
commit 571e6c9105
2 changed files with 19 additions and 4 deletions
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21
modules/video_coding/codecs/vp9/svc_rate_allocator.cc
View File

@ -95,9 +95,24 @@ BitrateAllocation SvcRateAllocator::GetAllocation(uint32_t total_bitrate_bps,
SplitBitrate(num_temporal_layers, spatial_layer_bitrate_bps[sl_idx],
kTemporalLayeringRateScalingFactor);
for (size_t tl_idx = 0; tl_idx < num_temporal_layers; ++tl_idx) {
bitrate_allocation.SetBitrate(sl_idx, num_temporal_layers - tl_idx - 1,
temporal_layer_bitrate_bps[tl_idx]);
// Distribute rate across temporal layers. Allocate more bits to lower
// layers since they are used for prediction of higher layers and their
// references are far apart.
if (num_temporal_layers == 1) {
bitrate_allocation.SetBitrate(sl_idx, 0, temporal_layer_bitrate_bps[0]);
} else if (num_temporal_layers == 2) {
bitrate_allocation.SetBitrate(sl_idx, 0, temporal_layer_bitrate_bps[1]);
bitrate_allocation.SetBitrate(sl_idx, 1, temporal_layer_bitrate_bps[0]);
} else {
RTC_CHECK_EQ(num_temporal_layers, 3);
// In case of three temporal layers the high layer has two frames and the
// middle layer has one frame within GOP (in between two consecutive low
// layer frames). Thus high layer requires more bits (comparing pure
// bitrate of layer, excluding bitrate of base layers) to keep quality on
// par with lower layers.
bitrate_allocation.SetBitrate(sl_idx, 0, temporal_layer_bitrate_bps[2]);
bitrate_allocation.SetBitrate(sl_idx, 1, temporal_layer_bitrate_bps[0]);
bitrate_allocation.SetBitrate(sl_idx, 2, temporal_layer_bitrate_bps[1]);
}
}