z-bar-qt/Plugins/ZShell/Wallpaper/videotranscoder.cpp

#include "videotranscoder.hpp"

#include <QCryptographicHash>
#include <QDir>
#include <QFileInfo>
#include <QFile>
#include <QProcess>
#include <QStringList>

#include <QtLogging>

Q_LOGGING_CATEGORY(transcodeLog, "ZShell.Internal.wallpaper")

namespace ZShell::wallpaper {

VideoTranscoder::VideoTranscoder(QObject* parent) : QObject(parent) {}

bool VideoTranscoder::isHardwareCodec(const QString& codec) {
	static const QStringList hardware{
		"av1",
		"hevc",
		"h264",
		"vp9",
		"vp8",
		"vc1",
		"mpeg2",
		"mpeg2video",
		"mpeg4",
		"mjpeg",
	};

	return hardware.contains(codec);
}

QString VideoTranscoder::codecName(const QString& path) const {
	QProcess probe;
	probe.start(
		"ffprobe",
		{
			"-v",
			"error",
			"-select_streams",
			"v:0",
			"-show_entries",
			"stream=codec_name",
			"-of",
			"default=nw=1:nk=1",
			path,
		});

	if (!probe.waitForFinished(2000) || probe.exitCode() != 0) {
		qWarning(transcodeLog) << "WallpaperService: ffprobe failed for" << path
								<< "(exit" << probe.exitCode() << ")";
		return {};
	}

	return QString::fromUtf8(probe.readAllStandardOutput()).trimmed().toLower();
}

QString VideoTranscoder::cacheDir() const {
	return QDir::homePath() + "/.cache/zshell/wallpaper-videos";
}

QString VideoTranscoder::transcodeTarget(const QString& path) const {
	const QFileInfo info(path);

	const QByteArray key =
		path.toUtf8() + '|' + QByteArray::number(info.size()) + '|' +
		QByteArray::number(info.lastModified().toMSecsSinceEpoch());

	const QString hash = QString::fromUtf8(
		QCryptographicHash::hash(key, QCryptographicHash::Sha1).toHex());

	return cacheDir() + '/' + hash + ".av1.mkv";
}

bool VideoTranscoder::needsTranscode(const QString& path) const {
	if (path.startsWith(cacheDir())) return false;

	const QString codec = codecName(path);
	if (codec.isEmpty()) return false;

	return !isHardwareCodec(codec);
}

void VideoTranscoder::start(const QString& src, const QString& dst) {
	QDir().mkpath(cacheDir());

	if (m_process) {
		m_process->kill();
		m_process->deleteLater();
		m_process = nullptr;
	}

	m_process = new QProcess(this);
	auto* proc = m_process;

	connect(proc, &QProcess::readyReadStandardError, proc, [proc]() {
		qWarning(transcodeLog).noquote()
			<< "ffmpeg:" << QString::fromUtf8(proc->readAllStandardError());
	});

	connect(
		proc,
		&QProcess::finished,
		this,
		[this, proc, dst](int code, QProcess::ExitStatus status) {
			const bool ok = code == 0 && status == QProcess::NormalExit &&
							QFile::exists(dst);

			qWarning(transcodeLog)
				<< "WallpaperService: transcode finished, exit" << code
				<< "status" << int(status) << "exists" << QFile::exists(dst)
				<< "->" << dst;

			if (proc == m_process) m_process = nullptr;
			proc->deleteLater();

			emit transcoded(dst, ok);
		});

	qWarning(transcodeLog) << "WallpaperService: transcoding" << src << "->"
							<< dst;

	proc->setProgram("nice");
	proc->setArguments({
		"-n",
		"19",
		"ffmpeg",
		"-hide_banner",
		"-loglevel",
		"error",
		"-y",
		"-threads",
		"2",
		"-i",
		src,
		"-map",
		"0:v:0",
		"-vf",
		"scale=in_range=pc:out_range=tv:out_color_matrix=bt709",
		"-colorspace",
		"bt709",
		"-color_primaries",
		"bt709",
		"-color_trc",
		"bt709",
		"-color_range",
		"tv",
		"-c:v",
		"libsvtav1",
		"-preset",
		"6",
		"-crf",
		"20",
		"-pix_fmt",
		"yuv420p10le",
		"-an",
		dst,
	});

	proc->start();
}

} // namespace ZShell::wallpaper