Allow extremely low resolution for simulcast path
Some screen capturers may occasionally send an extremely small frame,
e.g. 2x2. If a scale_resolution_down_by is specified, WebrtcVideoEngine
would enforce configured resolution to be at least 16x16, which would
then break VideoStreamEncoder and cause a crash.
This changes disables scaling and alignment for extremely low resolutions.
Bug: chromium:1265303, webrtc:13371
Change-Id: Icdb736043e1fdf91fdde5a8e4b3c6a89f6b90577
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/236850
Reviewed-by: Niels Moller <nisse@webrtc.org>
Commit-Queue: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35420}
diff --git a/media/engine/webrtc_video_engine.cc b/media/engine/webrtc_video_engine.cc
index 6d17fe9..f9de3ff 100644
--- a/media/engine/webrtc_video_engine.cc
+++ b/media/engine/webrtc_video_engine.cc
@@ -57,6 +57,18 @@
// needed.
constexpr char kAv1xCodecName[] = "AV1X";
+int ScaleDownResolution(int resolution,
+ double scale_down_by,
+ int min_resolution) {
+ // Resolution is never scalied down to smaller than min_resolution.
+ // If the input resolution is already smaller than min_resolution,
+ // no scaling should be done at all.
+ if (resolution <= min_resolution)
+ return resolution;
+ return std::max(static_cast<int>(resolution / scale_down_by + 0.5),
+ min_resolution);
+}
+
const char* StreamTypeToString(
webrtc::VideoSendStream::StreamStats::StreamType type) {
switch (type) {
@@ -3584,13 +3596,13 @@
layer.max_framerate = max_framerate;
if (encoder_config.simulcast_layers[0].scale_resolution_down_by > 1.) {
- layer.width = std::max<size_t>(
- layer.width /
- encoder_config.simulcast_layers[0].scale_resolution_down_by,
+ layer.width = ScaleDownResolution(
+ layer.width,
+ encoder_config.simulcast_layers[0].scale_resolution_down_by,
kMinLayerSize);
- layer.height = std::max<size_t>(
- layer.height /
- encoder_config.simulcast_layers[0].scale_resolution_down_by,
+ layer.height = ScaleDownResolution(
+ layer.height,
+ encoder_config.simulcast_layers[0].scale_resolution_down_by,
kMinLayerSize);
}
@@ -3666,14 +3678,15 @@
const bool norm_size_configured =
webrtc::NormalizeSimulcastSizeExperiment::GetBase2Exponent().has_value();
const int normalized_width =
- (default_scale_factors_used || norm_size_configured)
+ (default_scale_factors_used || norm_size_configured) &&
+ (width >= kMinLayerSize)
? NormalizeSimulcastSize(width, encoder_config.number_of_streams)
: width;
const int normalized_height =
- (default_scale_factors_used || norm_size_configured)
+ (default_scale_factors_used || norm_size_configured) &&
+ (height >= kMinLayerSize)
? NormalizeSimulcastSize(height, encoder_config.number_of_streams)
: height;
-
for (size_t i = 0; i < layers.size(); ++i) {
layers[i].active = encoder_config.simulcast_layers[i].active;
layers[i].scalability_mode =
@@ -3691,12 +3704,10 @@
if (has_scale_resolution_down_by) {
const double scale_resolution_down_by = std::max(
encoder_config.simulcast_layers[i].scale_resolution_down_by, 1.0);
- layers[i].width = std::max(
- static_cast<int>(normalized_width / scale_resolution_down_by),
- kMinLayerSize);
- layers[i].height = std::max(
- static_cast<int>(normalized_height / scale_resolution_down_by),
- kMinLayerSize);
+ layers[i].width = ScaleDownResolution(
+ normalized_width, scale_resolution_down_by, kMinLayerSize);
+ layers[i].height = ScaleDownResolution(
+ normalized_height, scale_resolution_down_by, kMinLayerSize);
}
// Update simulcast bitrates with configured min and max bitrate.
if (encoder_config.simulcast_layers[i].min_bitrate_bps > 0) {
