the addition of a thumbnailer that works for videos

the previewSlideDelegate now uses the thumbnails instead

src/cpp/framedecoder.h

@@ -0,0 +1,78 @@
+/*
+    SPDX-FileCopyrightText: 2010 Dirk Vanden Boer <dirk.vdb@gmail.com>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+
+#ifndef MOVIEDECODER_H
+#define MOVIEDECODER_H
+
+#include <QString>
+
+class QImage;
+
+extern "C" {
+#include <libavcodec/avcodec.h>
+#include <libavfilter/avfilter.h>
+#include <libavfilter/buffersink.h>
+#include <libavfilter/buffersrc.h>
+#include <libavformat/avformat.h>
+}
+
+class FrameDecoder
+{
+public:
+    explicit FrameDecoder(const QString &filename, AVFormatContext *pavContext = nullptr);
+    ~FrameDecoder();
+
+    QString getCodec();
+    void seek(int timeInSeconds);
+    bool decodeVideoFrame();
+    void getScaledVideoFrame(int scaledSize, bool maintainAspectRatio, QImage &videoFrame);
+
+    int getWidth();
+    int getHeight();
+    int getDuration();
+
+    void initialize(const QString &filename);
+    void destroy();
+    bool getInitialized();
+
+private:
+    bool initializeVideo();
+
+    bool decodeVideoPacket();
+    bool getVideoPacket();
+    void convertAndScaleFrame(AVPixelFormat format, int scaledSize, bool maintainAspectRatio, int &scaledWidth, int &scaledHeight);
+    void createAVFrame(AVFrame **avFrame, quint8 **frameBuffer, int width, int height, AVPixelFormat format);
+    void calculateDimensions(int squareSize, bool maintainAspectRatio, int &destWidth, int &destHeight);
+
+    void deleteFilterGraph();
+    bool initFilterGraph(enum AVPixelFormat pixfmt, int width, int height);
+    bool processFilterGraph(AVFrame *dst, const AVFrame *src, enum AVPixelFormat pixfmt, int width, int height);
+
+private:
+    int m_VideoStream;
+    AVFormatContext *m_pFormatContext;
+    AVCodecContext *m_pVideoCodecContext;
+#if LIBAVCODEC_VERSION_INT < AV_VERSION_INT(59, 0, 100)
+    AVCodec *m_pVideoCodec;
+#else
+    const AVCodec *m_pVideoCodec;
+#endif
+    AVFrame *m_pFrame;
+    quint8 *m_pFrameBuffer;
+    AVPacket *m_pPacket;
+    bool m_FormatContextWasGiven;
+    bool m_AllowSeek;
+    bool m_initialized;
+    AVFilterContext *m_bufferSinkContext;
+    AVFilterContext *m_bufferSourceContext;
+    AVFilterGraph *m_filterGraph;
+    AVFrame *m_filterFrame;
+    int m_lastWidth;
+    int m_lastHeight;
+    enum AVPixelFormat m_lastPixfmt;
+};
+
+#endif