Aegisub/src/video_provider_cache.cpp

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// Copyright (c) 2013, Thomas Goyne <plorkyeran@aegisub.org>
//
// Permission to use, copy, modify, and distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
// ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
// OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
//
// Aegisub Project http://www.aegisub.org/
#include "include/aegisub/video_provider.h"
#include "options.h"
#include "video_frame.h"
#include <libaegisub/make_unique.h>
#include <list>
namespace {
/// A video frame and its frame number
struct CachedFrame {
VideoFrame frame;
int frame_number;
CachedFrame(VideoFrame const& frame, int frame_number)
: frame(frame), frame_number(frame_number) { }
CachedFrame(CachedFrame const&) = delete;
};
/// @class VideoProviderCache
/// @brief A wrapper around a video provider which provides LRU caching
class VideoProviderCache final : public VideoProvider {
/// The source provider to get frames from
std::unique_ptr<VideoProvider> master;
/// @brief Maximum size of the cache in bytes
///
/// Note that this is a soft limit. The cache stops allocating new frames
/// once it has exceeded the limit, but it never tries to shrink
const size_t max_cache_size = OPT_GET("Provider/Video/Cache/Size")->GetInt() << 20; // convert MB to bytes
/// Cache of video frames with the most recently used ones at the front
std::list<CachedFrame> cache;
public:
VideoProviderCache(std::unique_ptr<VideoProvider> master) : master(std::move(master)) { }
void GetFrame(int n, VideoFrame &frame) override;
void SetColorSpace(std::string const& m) override {
cache.clear();
return master->SetColorSpace(m);
}
int GetFrameCount() const override { return master->GetFrameCount(); }
int GetWidth() const override { return master->GetWidth(); }
int GetHeight() const override { return master->GetHeight(); }
double GetDAR() const override { return master->GetDAR(); }
agi::vfr::Framerate GetFPS() const override { return master->GetFPS(); }
std::vector<int> GetKeyFrames() const override { return master->GetKeyFrames(); }
std::string GetWarning() const override { return master->GetWarning(); }
std::string GetDecoderName() const override { return master->GetDecoderName(); }
std::string GetColorSpace() const override { return master->GetColorSpace(); }
std::string GetRealColorSpace() const override { return master->GetRealColorSpace(); }
bool ShouldSetVideoProperties() const override { return master->ShouldSetVideoProperties(); }
bool HasAudio() const override { return master->HasAudio(); }
};
void VideoProviderCache::GetFrame(int n, VideoFrame &out) {
size_t total_size = 0;
for (auto cur = cache.begin(); cur != cache.end(); ++cur) {
if (cur->frame_number == n) {
cache.splice(cache.begin(), cache, cur); // Move to front
out = cache.front().frame;
return;
}
total_size += cur->frame.data.size();
}
master->GetFrame(n, out);
if (total_size >= max_cache_size) {
cache.splice(cache.begin(), cache, --cache.end()); // Move last to front
cache.front().frame_number = n;
cache.front().frame = out;
}
else
cache.emplace_front(out, n);
}
}
std::unique_ptr<VideoProvider> CreateCacheVideoProvider(std::unique_ptr<VideoProvider> parent) {
return agi::make_unique<VideoProviderCache>(std::move(parent));
}