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Revert "video_layer_allocation: clean up unused code"

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This reverts commit 05b58ad77e79efc5b4750f40b5092f945f0fff4d.

Reason for revert: UB because the shift exponent (-2) is negative
(UB happens at this line https://source.chromium.org/chromium/chromium/src/+/main:third_party/webrtc/modules/rtp_rtcp/source/rtp_video_layers_allocation_extension.cc;l=279;drc=05b58ad77e79efc5b4750f40b5092f945f0fff4d).

Original change's description:
> video_layer_allocation: clean up unused code
>
> remove unused support for more than four spatial layer descriptions
> of temporal layers
>
> BUG=webrtc:12000
>
> Change-Id: I087bcd020897898636bdf9c838abafa8c73c53f3
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/281320
> Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
> Commit-Queue: Philipp Hancke <phancke@microsoft.com>
> Reviewed-by: Per Kjellander <perkj@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#38646}

Bug: webrtc:12000, webrtc:14678
Change-Id: Ib94a0dead98aeb84af9b91c0ca6ad0893e8f2874
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/283840
Auto-Submit: Mirko Bonadei <mbonadei@webrtc.org>
Owners-Override: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#38660}
This commit is contained in:
Mirko Bonadei
2022-11-17 09:57:02 +00:00
committed by WebRTC LUCI CQ
parent c30835c712
commit 9eb1ff3ac0
1 changed files with 17 additions and 7 deletions
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20
modules/rtp_rtcp/source/rtp_video_layers_allocation_extension.cc
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@ -184,12 +184,16 @@ bool RtpVideoLayersAllocationExtension::Write(
}
++write_at;
{ // Number of temporal layers per spatial layer (at most kMaxSpatialIds).
static_assert(VideoLayersAllocation::kMaxSpatialIds == 4);
{ // Number of temporal layers.
int bit_offset = 8;
*write_at = 0;
for (const auto& layer : allocation.active_spatial_layers) {
if (bit_offset == 0) {
bit_offset = 6;
*++write_at = 0;
} else {
bit_offset -= 2;
}
*write_at |=
((layer.target_bitrate_per_temporal_layer.size() - 1) << bit_offset);
}
@ -265,9 +269,8 @@ bool RtpVideoLayersAllocationExtension::Parse(
return false;
}
// Read number of temporal layers per spatial layer (at most kMaxSpatialIds),
// create `allocation->active_spatial_layers` while iterating though it.
static_assert(VideoLayersAllocation::kMaxSpatialIds == 4);
// Read number of temporal layers,
// Create `allocation->active_spatial_layers` while iterating though it.
int bit_offset = 8;
for (int stream_idx = 0; stream_idx < num_rtp_streams; ++stream_idx) {
for (int sid = 0; sid < VideoLayersAllocation::kMaxSpatialIds; ++sid) {
@ -275,7 +278,14 @@ bool RtpVideoLayersAllocationExtension::Parse(
continue;
}
if (bit_offset == 0) {
bit_offset = 6;
if (++read_at == end) {
return false;
}
} else {
bit_offset -= 2;
}
int num_temporal_layers = 1 + ((*read_at >> bit_offset) & 0b11);
allocation->active_spatial_layers.emplace_back();
auto& layer = allocation->active_spatial_layers.back();