Aegisub/aegisub/src/video_provider_cache.cpp

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// Copyright (c) 2008, Rodrigo Braz Monteiro
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// * Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
// * Neither the name of the Aegisub Group nor the names of its contributors
// may be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// Aegisub Project http://www.aegisub.org/
/// @file video_provider_cache.cpp
/// @brief Aggregate video provider caching previously requested frames
/// @ingroup video_input
///
#include "config.h"
#include "video_provider_cache.h"
#include "options.h"
#include "video_frame.h"
#include <algorithm>
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#include <functional>
/// A video frame and its frame number
struct CachedFrame : public AegiVideoFrame {
int frame_number;
};
VideoProviderCache::VideoProviderCache(VideoProvider *parent)
: master(parent)
, max_cache_size(OPT_GET("Provider/Video/Cache/Size")->GetInt() << 20) // convert MB to bytes
{
}
VideoProviderCache::~VideoProviderCache() {
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for_each(cache.begin(), cache.end(), std::mem_fn(&AegiVideoFrame::Clear));
}
const AegiVideoFrame VideoProviderCache::GetFrame(int n) {
size_t total_size = 0;
// See if frame is cached
for (auto cur = cache.begin(); cur != cache.end(); ++cur) {
if (cur->frame_number == n) {
cache.push_front(*cur);
cache.erase(cur);
return cache.front();
}
total_size += cur->memSize;
}
// Not cached, retrieve it
const AegiVideoFrame frame = master->GetFrame(n);
// Cache full, use oldest frame
if (total_size >= max_cache_size) {
cache.push_front(cache.back());
cache.pop_back();
}
// Cache not full, insert new one
else
cache.push_front(CachedFrame());
// Cache
cache.front().frame_number = n;
cache.front().CopyFrom(frame);
return cache.front();
}