oak-editor/app/codec/ffmpeg/ffmpegdecoder.h

/***

  Olive - Non-Linear Video Editor
  Copyright (C) 2022 Olive Team

  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with this program.  If not, see <http://www.gnu.org/licenses/>.

***/

#ifndef FFMPEGDECODER_H
#define FFMPEGDECODER_H

// Fixes weird define issue when including <avfilter.h>
#include <inttypes.h>

extern "C" {
#include <libavcodec/avcodec.h>
#include <libavfilter/avfilter.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <libswresample/swresample.h>
}

#include <QTimer>
#include <QVector>
#include <QWaitCondition>

#include "codec/decoder.h"
#include "common/ffmpegutils.h"

namespace olive
{

// 头文件里先备好枚举映射
static VideoParams::Interlacing FFmpegFieldOrderToOlive(AVFieldOrder fo)
{
	switch (fo) {
	case AV_FIELD_TT:          // 隔行，顶场在前
		return VideoParams::kInterlacedTopFirst;
	case AV_FIELD_BB:          // 隔行，底场在前
		return VideoParams::kInterlacedBottomFirst;
	case AV_FIELD_PROGRESSIVE:
	default:
		return VideoParams::kInterlaceNone;
	}
}

/**
 * @brief A Decoder derivative that wraps FFmpeg functions as on Olive decoder
 */
class FFmpegDecoder : public Decoder {
	Q_OBJECT
public:
	// Constructor
	FFmpegDecoder();

	// Destructor
	DECODER_DEFAULT_DESTRUCTOR(FFmpegDecoder)

	virtual QString id() const override;

	virtual bool SupportsVideo() override
	{
		return true;
	}
	virtual bool SupportsAudio() override
	{
		return true;
	}

	virtual FootageDescription Probe(const QString &filename,
									 CancelAtom *cancelled) const override;

protected:
	virtual bool OpenInternal() override;
	virtual TexturePtr
	RetrieveVideoInternal(const RetrieveVideoParams &p) override;
	virtual bool ConformAudioInternal(const QVector<QString> &filenames,
									  const AudioParams &params,
									  CancelAtom *cancelled) override;
	virtual void CloseInternal() override;

	virtual rational GetAudioStartOffset() const override;

private:
	class Instance {
	public:
		Instance();

		~Instance()
		{
			Close();
		}

		bool Open(const char *filename, int stream_index);

		bool IsOpen() const
		{
			return fmt_ctx_;
		}

		void Close();

		/**
     * @brief Uses the FFmpeg API to retrieve a packet (stored in pkt_) and decode it (stored in frame_)
     *
     * @return
     *
     * An FFmpeg error code, or >= 0 on success
     */
		int GetFrame(AVPacket *pkt, AVFrame *frame);

		const char *GetSubtitleHeader() const;

		int GetSubtitle(AVPacket *pkt, AVSubtitle *sub);

		int GetPacket(AVPacket *pkt);

		void Seek(int64_t timestamp);

		AVFormatContext *fmt_ctx() const
		{
			return fmt_ctx_;
		}

		AVStream *avstream() const
		{
			return avstream_;
		}
		AVCodecContext *codec_ctx()
		{
			return codec_ctx_;
		}

	private:
		AVFormatContext *fmt_ctx_;
		AVCodecContext *codec_ctx_;
		AVStream *avstream_;
		AVDictionary *opts_;
	};

	/**
   * @brief Handle an FFmpeg error code
   *
   * Uses the FFmpeg API to retrieve a descriptive string for this error code and sends it to Error(). As such, this
   * function also automatically closes the Decoder.
   *
   * @param error_code
   */
	static QString FFmpegError(int error_code);

	void FreeScaler();

	static PixelFormat GetNativePixelFormat(AVPixelFormat pix_fmt);
	static int GetNativeChannelCount(AVPixelFormat pix_fmt);

	static AVChannelLayout ValidateChannelLayout(AVStream *stream);

	static const char *
	GetInterlacingModeInFFmpeg(VideoParams::Interlacing interlacing);

	static bool IsPixelFormatGLSLCompatible(AVPixelFormat f);

	AVFramePtr GetFrameFromCache(const int64_t &t) const;

	void ClearFrameCache();

	AVFramePtr PreProcessFrame(AVFramePtr f, const RetrieveVideoParams &p);

	TexturePtr ProcessFrameIntoTexture(AVFramePtr f,
									   const RetrieveVideoParams &p,
									   const AVFramePtr original);

	AVFramePtr RetrieveFrame(const rational &time, CancelAtom *cancelled);

	void RemoveFirstFrame();

	static int MaximumQueueSize();

	SwsContext *sws_ctx_;
	int sws_src_width_;
	int sws_src_height_;
	AVPixelFormat sws_src_format_;
	int sws_dst_width_;
	int sws_dst_height_;
	AVPixelFormat sws_dst_format_;
	AVColorRange sws_colrange_;
	AVColorSpace sws_colspace_;

	AVPacket *working_packet_;

	int64_t second_ts_;

	std::list<AVFramePtr> cached_frames_;

	bool cache_at_zero_;
	bool cache_at_eof_;

	Instance instance_;
};

}

#endif // FFMPEGDECODER_H