moonlight-qt/app/streaming/video/ffmpeg-renderers/pacer/pacer.cpp

154 lines
3.9 KiB
C++

#include "pacer.h"
#ifdef Q_OS_DARWIN
#include "displaylinkvsyncsource.h"
#endif
#ifdef Q_OS_WIN32
#include "dxvsyncsource.h"
#endif
#define FRAME_HISTORY_ENTRIES 8
Pacer::Pacer(IFFmpegRenderer* renderer) :
m_FrameQueueLock(0),
m_VsyncSource(nullptr),
m_VsyncRenderer(renderer),
m_MaxVideoFps(0),
m_DisplayFps(0)
{
}
Pacer::~Pacer()
{
// Stop V-sync callbacks
delete m_VsyncSource;
m_VsyncSource = nullptr;
while (!m_FrameQueue.isEmpty()) {
AVFrame* frame = m_FrameQueue.dequeue();
av_frame_free(&frame);
}
}
// Called in an arbitrary thread by the IVsyncSource on V-sync
// or an event synchronized with V-sync
void Pacer::vsyncCallback()
{
// Make sure initialize() has been called
SDL_assert(m_MaxVideoFps != 0);
SDL_AtomicLock(&m_FrameQueueLock);
// If the queue length history entries are large, be strict
// about dropping excess frames.
int frameDropTarget = 1;
// If we may get more frames per second than we can display, use
// frame history to drop frames only if consistently above the
// one queued frame mark.
if (m_MaxVideoFps >= m_DisplayFps) {
for (int i = 0; i < m_FrameQueueHistory.count(); i++) {
if (m_FrameQueueHistory[i] <= 1) {
// Be lenient as long as the queue length
// resolves before the end of frame history
frameDropTarget = 3;
break;
}
}
if (m_FrameQueueHistory.count() == FRAME_HISTORY_ENTRIES) {
m_FrameQueueHistory.dequeue();
}
m_FrameQueueHistory.enqueue(m_FrameQueue.count());
}
// Catch up if we're several frames ahead
while (m_FrameQueue.count() > frameDropTarget) {
AVFrame* frame = m_FrameQueue.dequeue();
av_frame_free(&frame);
}
if (m_FrameQueue.isEmpty()) {
SDL_AtomicUnlock(&m_FrameQueueLock);
// Nothing to render at this time
return;
}
// Grab the first frame
AVFrame* frame = m_FrameQueue.dequeue();
SDL_AtomicUnlock(&m_FrameQueueLock);
// Render it
m_VsyncRenderer->renderFrameAtVsync(frame);
// Free the frame
av_frame_free(&frame);
}
bool Pacer::initialize(SDL_Window* window, int maxVideoFps)
{
m_MaxVideoFps = maxVideoFps;
int displayIndex = SDL_GetWindowDisplayIndex(window);
if (displayIndex < 0) {
SDL_LogError(SDL_LOG_CATEGORY_APPLICATION,
"Failed to get current display: %s",
SDL_GetError());
// Assume display 0 if it fails
displayIndex = 0;
}
SDL_DisplayMode mode;
if (SDL_GetCurrentDisplayMode(displayIndex, &mode) == 0) {
// May be zero if undefined
m_DisplayFps = mode.refresh_rate;
}
SDL_LogInfo(SDL_LOG_CATEGORY_APPLICATION,
"Frame pacing: target %d Hz with %d FPS stream",
m_DisplayFps, m_MaxVideoFps);
#if defined(Q_OS_DARWIN)
m_VsyncSource = new DisplayLinkVsyncSource(this);
#elif defined(Q_OS_WIN32)
m_VsyncSource = new DxVsyncSource(this);
#else
// Platforms without a VsyncSource will just render frames
// immediately like they used to.
#endif
if (m_VsyncSource != nullptr && !m_VsyncSource->initialize(window)) {
return false;
}
return true;
}
void Pacer::submitFrame(AVFrame* frame)
{
// Make sure initialize() has been called
SDL_assert(m_MaxVideoFps != 0);
// Queue the frame until the V-sync callback if
// we have a V-sync source, otherwise deliver it
// immediately and hope for the best.
if (isUsingFrameQueue()) {
SDL_AtomicLock(&m_FrameQueueLock);
m_FrameQueue.enqueue(frame);
SDL_AtomicUnlock(&m_FrameQueueLock);
}
else {
m_VsyncRenderer->renderFrameAtVsync(frame);
av_frame_free(&frame);
}
}
bool Pacer::isUsingFrameQueue()
{
return m_VsyncSource != nullptr;
}