From 8877ce273f63048b1e78d1453bb87da34f6937ec Mon Sep 17 00:00:00 2001
From: kkostiuk <kateryna.kostiuk@savoirfairelinux.com>
Date: Wed, 24 Feb 2021 11:26:38 -0500
Subject: [PATCH] video: improve CPU usage on decoding
When frame decoding is fast, av_read_frame called before new data
available. It will cause high CPU usage.
This patch adds wait time when no data is available.
Change-Id: I675092e2497f969976f797cc1bbb6b466b9dbcb5
---
src/media/media_decoder.cpp | 15 +++++++++++++++
src/media/media_decoder.h | 1 +
2 files changed, 16 insertions(+)
diff --git a/src/media/media_decoder.cpp b/src/media/media_decoder.cpp
index 18f287e97a..894f4bde6d 100644
--- a/src/media/media_decoder.cpp
+++ b/src/media/media_decoder.cpp
@@ -325,6 +325,19 @@ MediaDemuxer::decode()
int ret = av_read_frame(inputCtx_, packet.get());
if (ret == AVERROR(EAGAIN)) {
+ /*no data available. Calculate time until next frame.
+ We do not use the emulated frame mechanism from the decoder because it will affect all platforms.
+ With the current implementation, the demuxer will be waiting just in case when av_read_frame
+ returns EAGAIN. For some platforms, av_read_frame is blocking and it will never happen.
+ */
+ if (inputParams_.framerate.numerator() == 0)
+ return Status::Success;
+ rational<double> frameTime = 1e6/inputParams_.framerate;
+ int64_t timeToSleep = lastReadPacketTime_ - av_gettime_relative() + frameTime.real<int64_t>();
+ if (timeToSleep <= 0) {
+ return Status::Success;
+ }
+ std::this_thread::sleep_for(std::chrono::microseconds(timeToSleep));
return Status::Success;
} else if (ret == AVERROR_EOF) {
return Status::EndOfFile;
@@ -338,6 +351,8 @@ MediaDemuxer::decode()
return Status::Success;
}
+ lastReadPacketTime_ = av_gettime_relative();
+
auto& cb = streams_[streamIndex];
if (cb) {
DecodeStatus ret = cb(*packet.get());
diff --git a/src/media/media_decoder.h b/src/media/media_decoder.h
index 917e54ab7a..826a9ab10b 100644
--- a/src/media/media_decoder.h
+++ b/src/media/media_decoder.h
@@ -131,6 +131,7 @@ private:
AVFormatContext* inputCtx_ = nullptr;
std::vector<StreamCallback> streams_;
int64_t startTime_;
+ int64_t lastReadPacketTime_ {};
DeviceParams inputParams_;
AVDictionary* options_ = nullptr;
MediaDemuxer::CurrentState currentState_;
--
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