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Add QVGA to thresholds for initial quality.

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Makes QualityScaler start at QVGA for <250k initial bitrates. Useful in
combination with overriding max bitrates to a max lower than that for
connections where we know that the max bitrate is capped below where VGA
is useful.

BUG=webrtc:5678
R=glaznev@webrtc.org

Review URL: https://codereview.webrtc.org/1900483004 .

Cr-Commit-Position: refs/heads/master@{#12416}
This commit is contained in:
Peter Boström
2016-04-18 22:45:55 +02:00
parent 3518c34477
commit b9e77097ed
2 changed files with 38 additions and 14 deletions
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22
webrtc/modules/video_coding/utility/quality_scaler.cc
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@ -18,11 +18,16 @@ static const int kMeasureSecondsFastUpscale = 2;
static const int kMeasureSecondsUpscale = 5;
static const int kMeasureSecondsDownscale = 5;
static const int kFramedropPercentThreshold = 60;
static const int kHdResolutionThreshold = 700 * 500;
static const int kHdBitrateThresholdKbps = 500;
// Min width/height to downscale to, set to not go below QVGA, but with some
// margin to permit "almost-QVGA" resolutions, such as QCIF.
static const int kMinDownscaleDimension = 140;
// Initial resolutions corresponding to a bitrate. Aa bit above their actual
// values to permit near-VGA and near-QVGA resolutions to use the same
// mechanism.
static const int kVgaBitrateThresholdKbps = 500;
static const int kVgaNumPixels = 700 * 500; // 640x480
static const int kQvgaBitrateThresholdKbps = 250;
static const int kQvgaNumPixels = 400 * 300; // 320x240
} // namespace
QualityScaler::QualityScaler()
@ -46,12 +51,13 @@ void QualityScaler::Init(int low_qp_threshold,
measure_seconds_upscale_ = kMeasureSecondsFastUpscale;
const int init_width = width;
const int init_height = height;
// TODO(glaznev): Investigate using thresholds for other resolutions
// or threshold tables.
if (initial_bitrate_kbps > 0 &&
initial_bitrate_kbps < kHdBitrateThresholdKbps) {
// Start scaling to roughly VGA.
while (width * height > kHdResolutionThreshold) {
if (initial_bitrate_kbps > 0) {
int init_num_pixels = width * height;
if (initial_bitrate_kbps < kVgaBitrateThresholdKbps)
init_num_pixels = kVgaNumPixels;
if (initial_bitrate_kbps < kQvgaBitrateThresholdKbps)
init_num_pixels = kQvgaNumPixels;
while (width * height > init_num_pixels) {
++downscale_shift_;
width /= 2;
height /= 2;

30
webrtc/modules/video_coding/utility/quality_scaler_unittest.cc
View File

@ -16,10 +16,8 @@ namespace webrtc {
namespace {
static const int kNumSeconds = 10;
static const int kWidth = 1920;
static const int kWidthVga = 640;
static const int kHalfWidth = kWidth / 2;
static const int kHeight = 1080;
static const int kHeightVga = 480;
static const int kFramerate = 30;
static const int kLowQp = 15;
static const int kNormalQp = 30;
@ -380,13 +378,33 @@ TEST_F(QualityScalerTest, DoesNotDownscaleBelow2xDefaultMinDimensionsHeight) {
}
TEST_F(QualityScalerTest, DownscaleToVgaOnLowInitialBitrate) {
qs_.Init(kLowQpThreshold, kDisabledBadQpThreshold, true,
kLowInitialBitrateKbps, kWidth, kHeight, kFramerate);
static const int kWidth720p = 1280;
static const int kHeight720p = 720;
static const int kInitialBitrateKbps = 300;
input_frame_.CreateEmptyFrame(kWidth720p, kHeight720p, kWidth720p,
kWidth720p / 2, kWidth720p / 2);
qs_.Init(kLowQpThreshold, kDisabledBadQpThreshold, true, kInitialBitrateKbps,
kWidth720p, kHeight720p, kFramerate);
qs_.OnEncodeFrame(input_frame_);
int init_width = qs_.GetScaledResolution().width;
int init_height = qs_.GetScaledResolution().height;
EXPECT_LE(init_width, kWidthVga);
EXPECT_LE(init_height, kHeightVga);
EXPECT_EQ(640, init_width);
EXPECT_EQ(360, init_height);
}
TEST_F(QualityScalerTest, DownscaleToQvgaOnLowerInitialBitrate) {
static const int kWidth720p = 1280;
static const int kHeight720p = 720;
static const int kInitialBitrateKbps = 200;
input_frame_.CreateEmptyFrame(kWidth720p, kHeight720p, kWidth720p,
kWidth720p / 2, kWidth720p / 2);
qs_.Init(kLowQpThreshold, kDisabledBadQpThreshold, true, kInitialBitrateKbps,
kWidth720p, kHeight720p, kFramerate);
qs_.OnEncodeFrame(input_frame_);
int init_width = qs_.GetScaledResolution().width;
int init_height = qs_.GetScaledResolution().height;
EXPECT_EQ(320, init_width);
EXPECT_EQ(180, init_height);
}
TEST_F(QualityScalerTest, DownscaleAfterMeasuredSecondsThenSlowerBackUp) {