init

Telegram/SourceFiles/ffmpeg/ffmpeg_utility.cpp

@@ -0,0 +1,748 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#include "ffmpeg/ffmpeg_utility.h"
+
+#include "base/algorithm.h"
+#include "logs.h"
+
+#if !defined Q_OS_WIN && !defined Q_OS_MAC
+#include "base/platform/linux/base_linux_library.h"
+#include <deque>
+#endif // !Q_OS_WIN && !Q_OS_MAC
+
+#include <QImage>
+
+#ifdef LIB_FFMPEG_USE_QT_PRIVATE_API
+#include <private/qdrawhelper_p.h>
+#endif // LIB_FFMPEG_USE_QT_PRIVATE_API
+
+extern "C" {
+#include <libavutil/opt.h>
+#include <libavutil/display.h>
+} // extern "C"
+
+#if !defined Q_OS_WIN && !defined Q_OS_MAC
+extern "C" {
+void _libvdpau_so_tramp_resolve_all(void) __attribute__((weak));
+void _libva_drm_so_tramp_resolve_all(void) __attribute__((weak));
+void _libva_x11_so_tramp_resolve_all(void) __attribute__((weak));
+void _libva_so_tramp_resolve_all(void) __attribute__((weak));
+void _libdrm_so_tramp_resolve_all(void) __attribute__((weak));
+} // extern "C"
+#endif // !Q_OS_WIN && !Q_OS_MAC
+
+namespace FFmpeg {
+namespace {
+
+// See https://github.com/telegramdesktop/tdesktop/issues/7225
+constexpr auto kAlignImageBy = 64;
+constexpr auto kImageFormat = QImage::Format_ARGB32_Premultiplied;
+constexpr auto kMaxScaleByAspectRatio = 16;
+constexpr auto kAvioBlockSize = 4096;
+constexpr auto kTimeUnknown = std::numeric_limits<crl::time>::min();
+constexpr auto kDurationMax = crl::time(std::numeric_limits<int>::max());
+
+using GetFormatMethod = enum AVPixelFormat(*)(
+	struct AVCodecContext *s,
+	const enum AVPixelFormat *fmt);
+
+struct HwAccelDescriptor {
+	GetFormatMethod getFormat = nullptr;
+	AVPixelFormat format = AV_PIX_FMT_NONE;
+};
+
+void AlignedImageBufferCleanupHandler(void* data) {
+	const auto buffer = static_cast<uchar*>(data);
+	delete[] buffer;
+}
+
+[[nodiscard]] bool IsValidAspectRatio(AVRational aspect) {
+	return (aspect.num > 0)
+		&& (aspect.den > 0)
+		&& (aspect.num <= aspect.den * kMaxScaleByAspectRatio)
+		&& (aspect.den <= aspect.num * kMaxScaleByAspectRatio);
+}
+
+[[nodiscard]] bool IsAlignedImage(const QImage &image) {
+	return !(reinterpret_cast<uintptr_t>(image.bits()) % kAlignImageBy)
+		&& !(image.bytesPerLine() % kAlignImageBy);
+}
+
+void UnPremultiplyLine(uchar *dst, const uchar *src, int intsCount) {
+	[[maybe_unused]] const auto udst = reinterpret_cast<uint*>(dst);
+	const auto usrc = reinterpret_cast<const uint*>(src);
+
+#ifndef LIB_FFMPEG_USE_QT_PRIVATE_API
+	for (auto i = 0; i != intsCount; ++i) {
+		udst[i] = qUnpremultiply(usrc[i]);
+	}
+#else // !LIB_FFMPEG_USE_QT_PRIVATE_API
+	static const auto layout = &qPixelLayouts[QImage::Format_ARGB32];
+	layout->storeFromARGB32PM(dst, usrc, 0, intsCount, nullptr, nullptr);
+#endif // LIB_FFMPEG_USE_QT_PRIVATE_API
+}
+
+void PremultiplyLine(uchar *dst, const uchar *src, int intsCount) {
+	const auto udst = reinterpret_cast<uint*>(dst);
+	[[maybe_unused]] const auto usrc = reinterpret_cast<const uint*>(src);
+
+#ifndef LIB_FFMPEG_USE_QT_PRIVATE_API
+	for (auto i = 0; i != intsCount; ++i) {
+		udst[i] = qPremultiply(usrc[i]);
+	}
+#else // !LIB_FFMPEG_USE_QT_PRIVATE_API
+	static const auto layout = &qPixelLayouts[QImage::Format_ARGB32];
+	layout->fetchToARGB32PM(udst, src, 0, intsCount, nullptr, nullptr);
+#endif // LIB_FFMPEG_USE_QT_PRIVATE_API
+}
+
+#if !defined Q_OS_WIN && !defined Q_OS_MAC
+[[nodiscard]] auto CheckHwLibs() {
+	auto list = std::deque{
+		AV_PIX_FMT_CUDA,
+	};
+	if (!_libvdpau_so_tramp_resolve_all
+			|| base::Platform::LoadLibrary("libvdpau.so.1")) {
+		list.push_front(AV_PIX_FMT_VDPAU);
+	}
+	if ([&] {
+		const auto list = std::array{
+			std::make_pair(_libva_drm_so_tramp_resolve_all, "libva-drm.so.2"),
+			std::make_pair(_libva_x11_so_tramp_resolve_all, "libva-x11.so.2"),
+			std::make_pair(_libva_so_tramp_resolve_all, "libva.so.2"),
+			std::make_pair(_libdrm_so_tramp_resolve_all, "libdrm.so.2"),
+		};
+		for (const auto &lib : list) {
+			if (lib.first && !base::Platform::LoadLibrary(lib.second)) {
+				return false;
+			}
+		}
+		return true;
+	}()) {
+		list.push_front(AV_PIX_FMT_VAAPI);
+	}
+	return list;
+}
+#endif // !Q_OS_WIN && !Q_OS_MAC
+
+[[nodiscard]] bool InitHw(AVCodecContext *context, AVHWDeviceType type) {
+	AVCodecContext *parent = static_cast<AVCodecContext*>(context->opaque);
+
+	auto hwDeviceContext = (AVBufferRef*)nullptr;
+	AvErrorWrap error = av_hwdevice_ctx_create(
+		&hwDeviceContext,
+		type,
+		nullptr,
+		nullptr,
+		0);
+	if (error || !hwDeviceContext) {
+		LogError(u"av_hwdevice_ctx_create"_q, error);
+		return false;
+	}
+	DEBUG_LOG(("Video Info: "
+		"Trying \"%1\" hardware acceleration for \"%2\" decoder."
+		).arg(
+			av_hwdevice_get_type_name(type),
+			context->codec->name));
+	if (parent->hw_device_ctx) {
+		av_buffer_unref(&parent->hw_device_ctx);
+	}
+	parent->hw_device_ctx = av_buffer_ref(hwDeviceContext);
+	av_buffer_unref(&hwDeviceContext);
+
+	context->hw_device_ctx = parent->hw_device_ctx;
+	return true;
+}
+
+[[nodiscard]] enum AVPixelFormat GetHwFormat(
+		AVCodecContext *context,
+		const enum AVPixelFormat *formats) {
+	const auto has = [&](enum AVPixelFormat format) {
+		const enum AVPixelFormat *p = nullptr;
+		for (p = formats; *p != AV_PIX_FMT_NONE; p++) {
+			if (*p == format) {
+				return true;
+			}
+		}
+		return false;
+	};
+#if defined Q_OS_WIN || defined Q_OS_MAC
+	const auto list = std::array{
+#ifdef Q_OS_WIN
+		AV_PIX_FMT_D3D11,
+		AV_PIX_FMT_DXVA2_VLD,
+		AV_PIX_FMT_CUDA,
+#elif defined Q_OS_MAC // Q_OS_WIN
+		AV_PIX_FMT_VIDEOTOOLBOX,
+#endif // Q_OS_WIN || Q_OS_MAC
+	};
+#else // Q_OS_WIN || Q_OS_MAC
+	static const auto list = CheckHwLibs();
+#endif // !Q_OS_WIN && !Q_OS_MAC
+	for (const auto format : list) {
+		if (!has(format)) {
+			continue;
+		}
+		const auto type = [&] {
+			switch (format) {
+#ifdef Q_OS_WIN
+			case AV_PIX_FMT_D3D11: return AV_HWDEVICE_TYPE_D3D11VA;
+			case AV_PIX_FMT_DXVA2_VLD: return AV_HWDEVICE_TYPE_DXVA2;
+			case AV_PIX_FMT_CUDA: return AV_HWDEVICE_TYPE_CUDA;
+#elif defined Q_OS_MAC // Q_OS_WIN
+			case AV_PIX_FMT_VIDEOTOOLBOX:
+				return AV_HWDEVICE_TYPE_VIDEOTOOLBOX;
+#else // Q_OS_WIN || Q_OS_MAC
+			case AV_PIX_FMT_VAAPI: return AV_HWDEVICE_TYPE_VAAPI;
+			case AV_PIX_FMT_VDPAU: return AV_HWDEVICE_TYPE_VDPAU;
+			case AV_PIX_FMT_CUDA: return AV_HWDEVICE_TYPE_CUDA;
+#endif // Q_OS_WIN || Q_OS_MAC
+			}
+			return AV_HWDEVICE_TYPE_NONE;
+		}();
+		if (type == AV_HWDEVICE_TYPE_NONE && context->hw_device_ctx) {
+			av_buffer_unref(&context->hw_device_ctx);
+		} else if (type != AV_HWDEVICE_TYPE_NONE && !InitHw(context, type)) {
+			continue;
+		}
+		return format;
+	}
+	enum AVPixelFormat result = AV_PIX_FMT_NONE;
+	for (const enum AVPixelFormat *p = formats; *p != AV_PIX_FMT_NONE; p++) {
+		result = *p;
+	}
+	return result;
+}
+
+template <AVPixelFormat Required>
+enum AVPixelFormat GetFormatImplementation(
+		AVCodecContext *ctx,
+		const enum AVPixelFormat *pix_fmts) {
+	const enum AVPixelFormat *p = nullptr;
+	for (p = pix_fmts; *p != -1; p++) {
+		if (*p == Required) {
+			return *p;
+		}
+	}
+	return AV_PIX_FMT_NONE;
+}
+
+} // namespace
+
+IOPointer MakeIOPointer(
+		void *opaque,
+		int(*read)(void *opaque, uint8_t *buffer, int bufferSize),
+#if DA_FFMPEG_CONST_WRITE_CALLBACK
+		int(*write)(void *opaque, const uint8_t *buffer, int bufferSize),
+#else
+		int(*write)(void *opaque, uint8_t *buffer, int bufferSize),
+#endif
+		int64_t(*seek)(void *opaque, int64_t offset, int whence)) {
+	auto buffer = reinterpret_cast<uchar*>(av_malloc(kAvioBlockSize));
+	if (!buffer) {
+		LogError(u"av_malloc"_q);
+		return {};
+	}
+	auto result = IOPointer(avio_alloc_context(
+		buffer,
+		kAvioBlockSize,
+		write ? 1 : 0,
+		opaque,
+		read,
+		write,
+		seek));
+	if (!result) {
+		av_freep(&buffer);
+		LogError(u"avio_alloc_context"_q);
+		return {};
+	}
+	return result;
+}
+
+void IODeleter::operator()(AVIOContext *value) {
+	if (value) {
+		av_freep(&value->buffer);
+		avio_context_free(&value);
+	}
+}
+
+FormatPointer MakeFormatPointer(
+		void *opaque,
+		int(*read)(void *opaque, uint8_t *buffer, int bufferSize),
+#if DA_FFMPEG_CONST_WRITE_CALLBACK
+		int(*write)(void *opaque, const uint8_t *buffer, int bufferSize),
+#else
+		int(*write)(void *opaque, uint8_t *buffer, int bufferSize),
+#endif
+		int64_t(*seek)(void *opaque, int64_t offset, int whence)) {
+	auto io = MakeIOPointer(opaque, read, write, seek);
+	if (!io) {
+		return {};
+	}
+	io->seekable = (seek != nullptr);
+	auto result = avformat_alloc_context();
+	if (!result) {
+		LogError(u"avformat_alloc_context"_q);
+		return {};
+	}
+	result->pb = io.get();
+	result->flags |= AVFMT_FLAG_CUSTOM_IO;
+
+	auto options = (AVDictionary*)nullptr;
+	const auto guard = gsl::finally([&] { av_dict_free(&options); });
+	av_dict_set(&options, "usetoc", "1", 0);
+
+	const auto error = AvErrorWrap(avformat_open_input(
+		&result,
+		nullptr,
+		nullptr,
+		&options));
+	if (error) {
+		// avformat_open_input freed 'result' in case an error happened.
+		LogError(u"avformat_open_input"_q, error);
+		return {};
+	}
+	if (seek) {
+		result->flags |= AVFMT_FLAG_FAST_SEEK;
+	}
+
+	// Now FormatPointer will own and free the IO context.
+	io.release();
+	return FormatPointer(result);
+}
+
+FormatPointer MakeWriteFormatPointer(
+		void *opaque,
+		int(*read)(void *opaque, uint8_t *buffer, int bufferSize),
+#if DA_FFMPEG_CONST_WRITE_CALLBACK
+		int(*write)(void *opaque, const uint8_t *buffer, int bufferSize),
+#else
+		int(*write)(void *opaque, uint8_t *buffer, int bufferSize),
+#endif
+		int64_t(*seek)(void *opaque, int64_t offset, int whence),
+		const QByteArray &format) {
+	const AVOutputFormat *found = nullptr;
+	void *i = nullptr;
+	while ((found = av_muxer_iterate(&i))) {
+		if (found->name == format) {
+			break;
+		}
+	}
+	if (!found) {
+		LogError(
+			"av_muxer_iterate",
+			u"Format %1 not found"_q.arg(QString::fromUtf8(format)));
+		return {};
+	}
+
+	auto io = MakeIOPointer(opaque, read, write, seek);
+	if (!io) {
+		return {};
+	}
+	io->seekable = (seek != nullptr);
+
+	auto result = (AVFormatContext*)nullptr;
+	auto error = AvErrorWrap(avformat_alloc_output_context2(
+		&result,
+		(AVOutputFormat*)found,
+		nullptr,
+		nullptr));
+	if (!result || error) {
+		LogError("avformat_alloc_output_context2", error);
+		return {};
+	}
+	result->pb = io.get();
+	result->flags |= AVFMT_FLAG_CUSTOM_IO;
+
+	// Now FormatPointer will own and free the IO context.
+	io.release();
+	return FormatPointer(result);
+}
+
+void FormatDeleter::operator()(AVFormatContext *value) {
+	if (value) {
+		const auto deleter = IOPointer(value->pb);
+		avformat_close_input(&value);
+	}
+}
+
+const AVCodec *FindDecoder(not_null<AVCodecContext*> context) {
+	// Force libvpx-vp9, because we need alpha channel support.
+	return (context->codec_id == AV_CODEC_ID_VP9)
+		? avcodec_find_decoder_by_name("libvpx-vp9")
+		: avcodec_find_decoder(context->codec_id);
+}
+
+CodecPointer MakeCodecPointer(CodecDescriptor descriptor) {
+	auto error = AvErrorWrap();
+
+	auto result = CodecPointer(avcodec_alloc_context3(nullptr));
+	const auto context = result.get();
+	if (!context) {
+		LogError(u"avcodec_alloc_context3"_q);
+		return {};
+	}
+	const auto stream = descriptor.stream;
+	error = avcodec_parameters_to_context(context, stream->codecpar);
+	if (error) {
+		LogError(u"avcodec_parameters_to_context"_q, error);
+		return {};
+	}
+	context->pkt_timebase = stream->time_base;
+	av_opt_set(context, "threads", "auto", 0);
+	av_opt_set_int(context, "refcounted_frames", 1, 0);
+
+	const auto codec = FindDecoder(context);
+	if (!codec) {
+		LogError(u"avcodec_find_decoder"_q, context->codec_id);
+		return {};
+	}
+
+	if (descriptor.hwAllowed) {
+		context->get_format = GetHwFormat;
+		context->opaque = context;
+	} else {
+		DEBUG_LOG(("Video Info: Using software \"%2\" decoder."
+			).arg(codec->name));
+	}
+
+	if ((error = avcodec_open2(context, codec, nullptr))) {
+		LogError(u"avcodec_open2"_q, error);
+		return {};
+	}
+	return result;
+}
+
+void CodecDeleter::operator()(AVCodecContext *value) {
+	if (value) {
+		avcodec_free_context(&value);
+	}
+}
+
+FramePointer MakeFramePointer() {
+	return FramePointer(av_frame_alloc());
+}
+
+FramePointer DuplicateFramePointer(AVFrame *frame) {
+	return frame
+		? FramePointer(av_frame_clone(frame))
+		: FramePointer();
+}
+
+bool FrameHasData(AVFrame *frame) {
+	return (frame && frame->data[0] != nullptr);
+}
+
+void ClearFrameMemory(AVFrame *frame) {
+	if (FrameHasData(frame)) {
+		av_frame_unref(frame);
+	}
+}
+
+void FrameDeleter::operator()(AVFrame *value) {
+	av_frame_free(&value);
+}
+
+SwscalePointer MakeSwscalePointer(
+		QSize srcSize,
+		int srcFormat,
+		QSize dstSize,
+		int dstFormat,
+		SwscalePointer *existing) {
+	// We have to use custom caching for SwsContext, because
+	// sws_getCachedContext checks passed flags with existing context flags,
+	// and re-creates context if they're different, but in the process of
+	// context creation the passed flags are modified before being written
+	// to the resulting context, so the caching doesn't work.
+	if (existing && (*existing) != nullptr) {
+		const auto &deleter = existing->get_deleter();
+		if (deleter.srcSize == srcSize
+			&& deleter.srcFormat == srcFormat
+			&& deleter.dstSize == dstSize
+			&& deleter.dstFormat == dstFormat) {
+			return std::move(*existing);
+		}
+	}
+	if (srcFormat <= AV_PIX_FMT_NONE || srcFormat >= AV_PIX_FMT_NB) {
+		LogError(u"frame->format"_q);
+		return SwscalePointer();
+	}
+
+	const auto result = sws_getCachedContext(
+		existing ? existing->release() : nullptr,
+		srcSize.width(),
+		srcSize.height(),
+		AVPixelFormat(srcFormat),
+		dstSize.width(),
+		dstSize.height(),
+		AVPixelFormat(dstFormat),
+		0,
+		nullptr,
+		nullptr,
+		nullptr);
+	if (!result) {
+		LogError(u"sws_getCachedContext"_q);
+	}
+	return SwscalePointer(
+		result,
+		{ srcSize, srcFormat, dstSize, dstFormat });
+}
+
+SwscalePointer MakeSwscalePointer(
+		not_null<AVFrame*> frame,
+		QSize resize,
+		SwscalePointer *existing) {
+	return MakeSwscalePointer(
+		QSize(frame->width, frame->height),
+		frame->format,
+		resize,
+		AV_PIX_FMT_BGRA,
+		existing);
+}
+
+void SwresampleDeleter::operator()(SwrContext *value) {
+	if (value) {
+		swr_free(&value);
+	}
+}
+
+SwresamplePointer MakeSwresamplePointer(
+		AVChannelLayout *srcLayout,
+		AVSampleFormat srcFormat,
+		int srcRate,
+		AVChannelLayout *dstLayout,
+		AVSampleFormat dstFormat,
+		int dstRate,
+		SwresamplePointer *existing) {
+	// We have to use custom caching for SwsContext, because
+	// sws_getCachedContext checks passed flags with existing context flags,
+	// and re-creates context if they're different, but in the process of
+	// context creation the passed flags are modified before being written
+	// to the resulting context, so the caching doesn't work.
+	if (existing && (*existing) != nullptr) {
+		const auto &deleter = existing->get_deleter();
+		if (srcLayout->nb_channels == deleter.srcChannels
+			&& dstLayout->nb_channels == deleter.dstChannels
+			&& srcFormat == deleter.srcFormat
+			&& dstFormat == deleter.dstFormat
+			&& srcRate == deleter.srcRate
+			&& dstRate == deleter.dstRate) {
+			return std::move(*existing);
+		}
+	}
+
+	// Initialize audio resampler
+	auto result = (SwrContext*)nullptr;
+	auto error = AvErrorWrap(swr_alloc_set_opts2(
+		&result,
+		dstLayout,
+		dstFormat,
+		dstRate,
+		srcLayout,
+		srcFormat,
+		srcRate,
+		0,
+		nullptr));
+	if (error || !result) {
+		LogError(u"swr_alloc_set_opts2"_q, error);
+		return SwresamplePointer();
+	}
+
+	error = AvErrorWrap(swr_init(result));
+	if (error) {
+		LogError(u"swr_init"_q, error);
+		swr_free(&result);
+		return SwresamplePointer();
+	}
+
+	return SwresamplePointer(
+		result,
+		{
+			srcFormat,
+			srcRate,
+			srcLayout->nb_channels,
+			dstFormat,
+			dstRate,
+			dstLayout->nb_channels,
+		});
+}
+
+void SwscaleDeleter::operator()(SwsContext *value) {
+	if (value) {
+		sws_freeContext(value);
+	}
+}
+
+void LogError(const QString &method, const QString &details) {
+	LOG(("Streaming Error: Error in %1%2."
+		).arg(method
+		).arg(details.isEmpty() ? QString() : " - " + details));
+}
+
+void LogError(
+		const QString &method,
+		AvErrorWrap error,
+		const QString &details) {
+	LOG(("Streaming Error: Error in %1 (code: %2, text: %3)%4."
+		).arg(method
+		).arg(error.code()
+		).arg(error.text()
+		).arg(details.isEmpty() ? QString() : " - " + details));
+}
+
+crl::time PtsToTime(int64_t pts, AVRational timeBase) {
+	return (pts == AV_NOPTS_VALUE || !timeBase.den)
+		? kTimeUnknown
+		: ((pts * 1000LL * timeBase.num) / timeBase.den);
+}
+
+crl::time PtsToTimeCeil(int64_t pts, AVRational timeBase) {
+	return (pts == AV_NOPTS_VALUE || !timeBase.den)
+		? kTimeUnknown
+		: ((pts * 1000LL * timeBase.num + timeBase.den - 1) / timeBase.den);
+}
+
+int64_t TimeToPts(crl::time time, AVRational timeBase) {
+	return (time == kTimeUnknown || !timeBase.num)
+		? AV_NOPTS_VALUE
+		: (time * timeBase.den) / (1000LL * timeBase.num);
+}
+
+crl::time PacketPosition(const Packet &packet, AVRational timeBase) {
+	const auto &native = packet.fields();
+	return PtsToTime(
+		(native.pts == AV_NOPTS_VALUE) ? native.dts : native.pts,
+		timeBase);
+}
+
+crl::time PacketDuration(const Packet &packet, AVRational timeBase) {
+	return PtsToTime(packet.fields().duration, timeBase);
+}
+
+int DurationByPacket(const Packet &packet, AVRational timeBase) {
+	const auto position = PacketPosition(packet, timeBase);
+	const auto duration = std::max(
+		PacketDuration(packet, timeBase),
+		crl::time(1));
+	const auto bad = [](crl::time time) {
+		return (time < 0) || (time > kDurationMax);
+	};
+	if (bad(position) || bad(duration) || bad(position + duration + 1)) {
+		LOG(("Streaming Error: Wrong duration by packet: %1 + %2"
+			).arg(position
+			).arg(duration));
+		return -1;
+	}
+	return int(position + duration + 1);
+}
+
+int ReadRotationFromMetadata(not_null<AVStream*> stream) {
+	const auto displaymatrix = av_packet_side_data_get(
+		stream->codecpar->coded_side_data,
+		stream->codecpar->nb_coded_side_data,
+		AV_PKT_DATA_DISPLAYMATRIX);
+	auto theta = 0;
+	if (displaymatrix) {
+		const auto matrix = (int32_t*)displaymatrix->data;
+		theta = -round(av_display_rotation_get(matrix));
+	}
+	theta -= 360 * floor(theta / 360 + 0.9 / 360);
+	const auto result = int(base::SafeRound(theta));
+	return (result == 90 || result == 180 || result == 270) ? result : 0;
+}
+
+AVRational ValidateAspectRatio(AVRational aspect) {
+	return IsValidAspectRatio(aspect) ? aspect : kNormalAspect;
+}
+
+QSize CorrectByAspect(QSize size, AVRational aspect) {
+	Expects(IsValidAspectRatio(aspect));
+
+	return QSize(size.width() * av_q2d(aspect), size.height());
+}
+
+bool RotationSwapWidthHeight(int rotation) {
+	return (rotation == 90 || rotation == 270);
+}
+
+QSize TransposeSizeByRotation(QSize size, int rotation) {
+	return RotationSwapWidthHeight(rotation) ? size.transposed() : size;
+}
+
+bool GoodStorageForFrame(const QImage &storage, QSize size) {
+	return !storage.isNull()
+		&& (storage.format() == kImageFormat)
+		&& (storage.size() == size)
+		&& storage.isDetached()
+		&& IsAlignedImage(storage);
+}
+
+// Create a QImage of desired size where all the data is properly aligned.
+QImage CreateFrameStorage(QSize size) {
+	const auto width = size.width();
+	const auto height = size.height();
+	const auto widthAlign = kAlignImageBy / kPixelBytesSize;
+	const auto neededWidth = width + ((width % widthAlign)
+		? (widthAlign - (width % widthAlign))
+		: 0);
+	const auto perLine = neededWidth * kPixelBytesSize;
+	const auto buffer = new uchar[perLine * height + kAlignImageBy];
+	const auto cleanupData = static_cast<void *>(buffer);
+	const auto address = reinterpret_cast<uintptr_t>(buffer);
+	const auto alignedBuffer = buffer + ((address % kAlignImageBy)
+		? (kAlignImageBy - (address % kAlignImageBy))
+		: 0);
+	return QImage(
+		alignedBuffer,
+		width,
+		height,
+		perLine,
+		kImageFormat,
+		AlignedImageBufferCleanupHandler,
+		cleanupData);
+}
+
+void UnPremultiply(QImage &dst, const QImage &src) {
+	// This creates QImage::Format_ARGB32_Premultiplied, but we use it
+	// as an image in QImage::Format_ARGB32 format.
+	if (!GoodStorageForFrame(dst, src.size())) {
+		dst = CreateFrameStorage(src.size());
+	}
+	const auto srcPerLine = src.bytesPerLine();
+	const auto dstPerLine = dst.bytesPerLine();
+	const auto width = src.width();
+	const auto height = src.height();
+	auto srcBytes = src.bits();
+	auto dstBytes = dst.bits();
+	if (srcPerLine != width * 4 || dstPerLine != width * 4) {
+		for (auto i = 0; i != height; ++i) {
+			UnPremultiplyLine(dstBytes, srcBytes, width);
+			srcBytes += srcPerLine;
+			dstBytes += dstPerLine;
+		}
+	} else {
+		UnPremultiplyLine(dstBytes, srcBytes, width * height);
+	}
+}
+
+void PremultiplyInplace(QImage &image) {
+	const auto perLine = image.bytesPerLine();
+	const auto width = image.width();
+	const auto height = image.height();
+	auto bytes = image.bits();
+	if (perLine != width * 4) {
+		for (auto i = 0; i != height; ++i) {
+			PremultiplyLine(bytes, bytes, width);
+			bytes += perLine;
+		}
+	} else {
+		PremultiplyLine(bytes, bytes, width * height);
+	}
+}
+
+} // namespace FFmpeg