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Increase frame rate precision in libaom AV1 encoder wrapper

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Before this change the AV1 encoder wrapper converted target frame rate from double to integer with rounding to the middle. That approach resulted in a bitrate mismatch caused by rounding error. The mismatch was especially high at low frame rates. For example, at target frame rate 1.4fps the bitrate mismatch reached 40%:

out/debug/video_codec_perf_tests --gtest_also_run_disabled_tests --gtest_filter=*EncodeDecode --framerate_fps=1.4 --width=320 --height=180 --bitrate_kbps=32 --num_frames=600
...
RESULT s0t0_bitrate_mismatch_pct: DISABLED_EncodeDecode= {39.171875,0} n%

After the change the mismatch reduced to ~2% in the same scenario:
RESULT s0t0_bitrate_mismatch_pct: DISABLED_EncodeDecode= {-2.178125,0} n%

Bug: b/337757868
Change-Id: Ia51f92b3dfdce103eed1d04cac0e084b69fa8213
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/356500
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Sergey Silkin <ssilkin@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#42601}
This commit is contained in:
Sergey Silkin 2024-07-08 07:42:17 +02:00 committed by WebRTC LUCI CQ
parent 41ffc51e45
commit b43cd86e64
1 changed files with 5 additions and 6 deletions
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11
modules/video_coding/codecs/av1/libaom_av1_encoder.cc
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@ -131,6 +131,7 @@ class LibaomAv1Encoder final : public VideoEncoder {
aom_codec_ctx_t ctx_; aom_codec_ctx_t ctx_;
aom_codec_enc_cfg_t cfg_; aom_codec_enc_cfg_t cfg_;
EncodedImageCallback* encoded_image_callback_; EncodedImageCallback* encoded_image_callback_;
double framerate_fps_; // Current target frame rate.
int64_t timestamp_; int64_t timestamp_;
const LibaomAv1EncoderInfoSettings encoder_info_override_; const LibaomAv1EncoderInfoSettings encoder_info_override_;
int max_consec_frame_drop_; int max_consec_frame_drop_;
@ -179,6 +180,7 @@ LibaomAv1Encoder::LibaomAv1Encoder(const Environment& env,
settings_(std::move(settings)), settings_(std::move(settings)),
frame_for_encode_(nullptr), frame_for_encode_(nullptr),
encoded_image_callback_(nullptr), encoded_image_callback_(nullptr),
framerate_fps_(0),
timestamp_(0), timestamp_(0),
encoder_info_override_(env.field_trials()), encoder_info_override_(env.field_trials()),
max_consec_frame_drop_(GetMaxConsecutiveFrameDrop(env.field_trials())) {} max_consec_frame_drop_(GetMaxConsecutiveFrameDrop(env.field_trials())) {}
@ -658,8 +660,7 @@ int32_t LibaomAv1Encoder::Encode(
return WEBRTC_VIDEO_CODEC_ENCODER_FAILURE; return WEBRTC_VIDEO_CODEC_ENCODER_FAILURE;
} }
const uint32_t duration = const uint32_t duration = kRtpTicksPerSecond / framerate_fps_;
kRtpTicksPerSecond / static_cast<float>(encoder_settings_.maxFramerate);
timestamp_ += duration; timestamp_ += duration;
const size_t num_spatial_layers = const size_t num_spatial_layers =
@ -836,11 +837,9 @@ void LibaomAv1Encoder::SetRates(const RateControlParameters& parameters) {
SetEncoderControlParameters(AV1E_SET_SVC_PARAMS, &*svc_params_); SetEncoderControlParameters(AV1E_SET_SVC_PARAMS, &*svc_params_);
} }
rates_configured_ = true; framerate_fps_ = parameters.framerate_fps;
// Set frame rate to closest integer value. rates_configured_ = true;
encoder_settings_.maxFramerate =
static_cast<uint32_t>(parameters.framerate_fps + 0.5);
} }
VideoEncoder::EncoderInfo LibaomAv1Encoder::GetEncoderInfo() const { VideoEncoder::EncoderInfo LibaomAv1Encoder::GetEncoderInfo() const {