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- // Copyright (C) 2023 The Qt Company Ltd.
- // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
-
- #include "qv4l2memorytransfer_p.h"
- #include "qv4l2filedescriptor_p.h"
-
- #include <qloggingcategory.h>
- #include <qdebug.h>
- #include <sys/mman.h>
- #include <optional>
-
- QT_BEGIN_NAMESPACE
-
- Q_STATIC_LOGGING_CATEGORY(qLcV4L2MemoryTransfer, "qt.multimedia.ffmpeg.v4l2camera.memorytransfer");
-
- namespace {
-
- v4l2_buffer makeV4l2Buffer(quint32 memoryType, quint32 index = 0)
- {
- v4l2_buffer buf = {};
- buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
- buf.memory = memoryType;
- buf.index = index;
- return buf;
- }
-
- class UserPtrMemoryTransfer : public QV4L2MemoryTransfer
- {
- public:
- static QV4L2MemoryTransferUPtr create(QV4L2FileDescriptorPtr fileDescriptor, quint32 imageSize)
- {
- quint32 buffersCount = 2;
- if (!fileDescriptor->requestBuffers(V4L2_MEMORY_USERPTR, buffersCount)) {
- qCDebug(qLcV4L2MemoryTransfer) << "Cannot request V4L2_MEMORY_USERPTR buffers";
- return {};
- }
-
- std::unique_ptr<UserPtrMemoryTransfer> result(
- new UserPtrMemoryTransfer(std::move(fileDescriptor), buffersCount, imageSize));
-
- return result->enqueueBuffers() ? std::move(result) : nullptr;
- }
-
- std::optional<Buffer> dequeueBuffer() override
- {
- auto v4l2Buffer = makeV4l2Buffer(V4L2_MEMORY_USERPTR);
- if (!fileDescriptor().call(VIDIOC_DQBUF, &v4l2Buffer))
- return {};
-
- Q_ASSERT(v4l2Buffer.index < m_byteArrays.size());
-
- auto &byteArray = m_byteArrays[v4l2Buffer.index];
-
- Q_ASSERT(!byteArray.isEmpty());
- Q_ASSERT(qsizetype(v4l2Buffer.bytesused) <= byteArray.size());
-
- // truncate jpeg
- byteArray.resize(v4l2Buffer.bytesused);
- return Buffer{ v4l2Buffer, std::move(byteArray) };
- }
-
- bool enqueueBuffer(quint32 index) override
- {
- Q_ASSERT(index < m_byteArrays.size());
- Q_ASSERT(m_byteArrays[index].isEmpty());
-
- auto buf = makeV4l2Buffer(V4L2_MEMORY_USERPTR, index);
- static_assert(sizeof(decltype(buf.m.userptr)) == sizeof(size_t), "Not compatible sizes");
-
- m_byteArrays[index] = QByteArray(static_cast<int>(m_imageSize), Qt::Uninitialized);
-
- buf.m.userptr = (decltype(buf.m.userptr))m_byteArrays[index].data();
- buf.length = m_byteArrays[index].size();
-
- if (!fileDescriptor().call(VIDIOC_QBUF, &buf)) {
- qWarning() << "Couldn't add V4L2 buffer" << errno << qt_error_string(errno) << index;
- return false;
- }
-
- return true;
- }
-
- quint32 buffersCount() const override { return static_cast<quint32>(m_byteArrays.size()); }
-
- private:
- UserPtrMemoryTransfer(QV4L2FileDescriptorPtr fileDescriptor, quint32 buffersCount,
- quint32 imageSize)
- : QV4L2MemoryTransfer(std::move(fileDescriptor)),
- m_imageSize(imageSize),
- m_byteArrays(buffersCount)
- {
- }
-
- private:
- quint32 m_imageSize;
- std::vector<QByteArray> m_byteArrays;
- };
-
- class MMapMemoryTransfer : public QV4L2MemoryTransfer
- {
- public:
- struct MemorySpan
- {
- void *data = nullptr;
- size_t size = 0;
- bool inQueue = false;
- };
-
- static QV4L2MemoryTransferUPtr create(QV4L2FileDescriptorPtr fileDescriptor)
- {
- quint32 buffersCount = 2;
- if (!fileDescriptor->requestBuffers(V4L2_MEMORY_MMAP, buffersCount)) {
- qCWarning(qLcV4L2MemoryTransfer) << "Cannot request V4L2_MEMORY_MMAP buffers";
- return {};
- }
-
- std::unique_ptr<MMapMemoryTransfer> result(
- new MMapMemoryTransfer(std::move(fileDescriptor)));
-
- return result->init(buffersCount) ? std::move(result) : nullptr;
- }
-
- bool init(quint32 buffersCount)
- {
- for (quint32 index = 0; index < buffersCount; ++index) {
- auto buf = makeV4l2Buffer(V4L2_MEMORY_MMAP, index);
-
- if (!fileDescriptor().call(VIDIOC_QUERYBUF, &buf)) {
- qWarning() << "Can't map buffer" << index;
- return false;
- }
-
- auto mappedData = mmap(nullptr, buf.length, PROT_READ | PROT_WRITE, MAP_SHARED,
- fileDescriptor().get(), buf.m.offset);
-
- if (mappedData == MAP_FAILED) {
- qWarning() << "mmap failed" << index << buf.length << buf.m.offset;
- return false;
- }
-
- m_spans.push_back(MemorySpan{ mappedData, buf.length, false });
- }
-
- m_spans.shrink_to_fit();
-
- return enqueueBuffers();
- }
-
- ~MMapMemoryTransfer() override
- {
- for (const auto &span : m_spans)
- munmap(span.data, span.size);
- }
-
- std::optional<Buffer> dequeueBuffer() override
- {
- auto v4l2Buffer = makeV4l2Buffer(V4L2_MEMORY_MMAP);
- if (!fileDescriptor().call(VIDIOC_DQBUF, &v4l2Buffer))
- return {};
-
- const auto index = v4l2Buffer.index;
-
- Q_ASSERT(index < m_spans.size());
-
- auto &span = m_spans[index];
-
- Q_ASSERT(span.inQueue);
- span.inQueue = false;
-
- Q_ASSERT(v4l2Buffer.bytesused <= span.size);
-
- // truncate jpeg
- QByteArray byteArray(reinterpret_cast<const char *>(span.data), v4l2Buffer.bytesused);
-
- return Buffer{ v4l2Buffer, std::move(byteArray) };
- }
-
- bool enqueueBuffer(quint32 index) override
- {
- Q_ASSERT(index < m_spans.size());
- Q_ASSERT(!m_spans[index].inQueue);
-
- auto buf = makeV4l2Buffer(V4L2_MEMORY_MMAP, index);
- if (!fileDescriptor().call(VIDIOC_QBUF, &buf))
- return false;
-
- m_spans[index].inQueue = true;
- return true;
- }
-
- quint32 buffersCount() const override { return static_cast<quint32>(m_spans.size()); }
-
- private:
- using QV4L2MemoryTransfer::QV4L2MemoryTransfer;
-
- private:
- std::vector<MemorySpan> m_spans;
- };
- } // namespace
-
- QV4L2MemoryTransfer::QV4L2MemoryTransfer(QV4L2FileDescriptorPtr fileDescriptor)
- : m_fileDescriptor(std::move(fileDescriptor))
- {
- Q_ASSERT(m_fileDescriptor);
- Q_ASSERT(!m_fileDescriptor->streamStarted());
- }
-
- QV4L2MemoryTransfer::~QV4L2MemoryTransfer()
- {
- Q_ASSERT(!m_fileDescriptor->streamStarted()); // to avoid possible corruptions
- }
-
- bool QV4L2MemoryTransfer::enqueueBuffers()
- {
- for (quint32 i = 0; i < buffersCount(); ++i)
- if (!enqueueBuffer(i))
- return false;
-
- return true;
- }
-
- QV4L2MemoryTransferUPtr makeUserPtrMemoryTransfer(QV4L2FileDescriptorPtr fileDescriptor,
- quint32 imageSize)
- {
- return UserPtrMemoryTransfer::create(std::move(fileDescriptor), imageSize);
- }
-
- QV4L2MemoryTransferUPtr makeMMapMemoryTransfer(QV4L2FileDescriptorPtr fileDescriptor)
- {
- return MMapMemoryTransfer::create(std::move(fileDescriptor));
- }
-
- QT_END_NAMESPACE