media/gpu/v4l2/v4l2_device.cc

// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "media/gpu/v4l2/v4l2_device.h"

#include <libdrm/drm_fourcc.h>
#include <linux/videodev2.h>
#include <string.h>
#include <sys/mman.h>
#include <sstream>

#include "base/bind.h"
#include "base/logging.h"
#include "base/numerics/safe_conversions.h"
#include "build/build_config.h"
#include "media/base/bind_to_current_loop.h"
#include "media/base/video_types.h"
#include "media/gpu/macros.h"
#include "media/gpu/v4l2/generic_v4l2_device.h"
#if defined(ARCH_CPU_ARMEL)
#include "media/gpu/v4l2/tegra_v4l2_device.h"
#endif

namespace media {

// Class used to store the state of a buffer that should persist between
// reference creations. This includes:
// * Result of initial VIDIOC_QUERYBUF ioctl,
// * Plane mappings.
//
// Also provides helper functions.
class V4L2Buffer {
 public:
  static std::unique_ptr<V4L2Buffer> Create(scoped_refptr<V4L2Device> device,
                                            enum v4l2_buf_type type,
                                            enum v4l2_memory memory,
                                            size_t planes_count,
                                            size_t buffer_id);
  ~V4L2Buffer();

  void* GetPlaneMapping(const size_t plane);
  size_t GetMemoryUsage() const;
  const struct v4l2_buffer* v4l2_buffer() const { return &v4l2_buffer_; }

 private:
  V4L2Buffer(scoped_refptr<V4L2Device> device,
             enum v4l2_buf_type type,
             enum v4l2_memory memory,
             size_t planes_count,
             size_t buffer_id);
  bool Query();

  scoped_refptr<V4L2Device> device_;
  std::vector<void*> plane_mappings_;

  // V4L2 data as queried by QUERYBUF.
  struct v4l2_buffer v4l2_buffer_ = {};
  // WARNING: do not change this to a vector or something smaller than
  // VIDEO_MAX_PLANES, otherwise the Tegra libv4l2 will write data beyond
  // the number of allocated planes, resulting in memory corruption.
  struct v4l2_plane v4l2_planes_[VIDEO_MAX_PLANES] = {{}};

  DISALLOW_COPY_AND_ASSIGN(V4L2Buffer);
};

std::unique_ptr<V4L2Buffer> V4L2Buffer::Create(scoped_refptr<V4L2Device> device,
                                               enum v4l2_buf_type type,
                                               enum v4l2_memory memory,
                                               size_t planes_count,
                                               size_t buffer_id) {
  // Not using std::make_unique because constructor is private.
  std::unique_ptr<V4L2Buffer> buffer(
      new V4L2Buffer(device, type, memory, planes_count, buffer_id));

  if (!buffer->Query())
    return nullptr;

  return buffer;
}

V4L2Buffer::V4L2Buffer(scoped_refptr<V4L2Device> device,
                       enum v4l2_buf_type type,
                       enum v4l2_memory memory,
                       size_t planes_count,
                       size_t buffer_id)
    : device_(device) {
  DCHECK(V4L2_TYPE_IS_MULTIPLANAR(type));
  DCHECK_LE(planes_count, base::size(v4l2_planes_));
  v4l2_buffer_.m.planes = v4l2_planes_;
  // Just in case we got more planes than we want.
  v4l2_buffer_.length = std::min(planes_count, base::size(v4l2_planes_));
  v4l2_buffer_.index = buffer_id;
  v4l2_buffer_.type = type;
  v4l2_buffer_.memory = memory;

  plane_mappings_.resize(v4l2_buffer_.length);
}

V4L2Buffer::~V4L2Buffer() {
  if (v4l2_buffer_.memory == V4L2_MEMORY_MMAP) {
    for (size_t i = 0; i < plane_mappings_.size(); i++)
      if (plane_mappings_[i] != nullptr)
        device_->Munmap(plane_mappings_[i], v4l2_buffer_.m.planes[i].length);
  }
}

bool V4L2Buffer::Query() {
  int ret = device_->Ioctl(VIDIOC_QUERYBUF, &v4l2_buffer_);
  if (ret) {
    VPLOGF(1) << "VIDIOC_QUERYBUF failed: ";
    return false;
  }

  DCHECK(plane_mappings_.size() == v4l2_buffer_.length);

  return true;
}

void* V4L2Buffer::GetPlaneMapping(const size_t plane) {
  if (plane >= plane_mappings_.size()) {
    VLOGF(1) << "Invalid plane " << plane << " requested.";
    return nullptr;
  }

  void* p = plane_mappings_[plane];
  if (p)
    return p;

  // Do this check here to avoid repeating it after a buffer has been
  // successfully mapped (we know we are of MMAP type by then).
  if (v4l2_buffer_.memory != V4L2_MEMORY_MMAP) {
    VLOGF(1) << "Cannot create mapping on non-MMAP buffer";
    return nullptr;
  }

  p = device_->Mmap(NULL, v4l2_buffer_.m.planes[plane].length,
                    PROT_READ | PROT_WRITE, MAP_SHARED,
                    v4l2_buffer_.m.planes[plane].m.mem_offset);
  if (p == MAP_FAILED) {
    VPLOGF(1) << "mmap() failed: ";
    return nullptr;
  }

  plane_mappings_[plane] = p;
  return p;
}

size_t V4L2Buffer::GetMemoryUsage() const {
  size_t usage = 0;
  for (size_t i = 0; i < v4l2_buffer_.length; i++) {
    usage += v4l2_buffer_.m.planes[i].length;
  }
  return usage;
}

// Module-private class that let users query/write V4L2 buffer information.
// It also makes some private V4L2Queue methods available to this module only.
class V4L2BufferQueueProxy {
 public:
  V4L2BufferQueueProxy(const struct v4l2_buffer* v4l2_buffer,
                       scoped_refptr<V4L2Queue> queue);

  void ReturnBuffer() { queue_->ReturnBuffer(BufferId()); }

  bool QueueBuffer();

  void* GetPlaneMapping(const size_t plane) {
    return queue_->buffers_[BufferId()]->GetPlaneMapping(plane);
  }

  // Data from the buffer, that users can query and/or write.
  struct v4l2_buffer v4l2_buffer_;
  // WARNING: do not change this to a vector or something smaller than
  // VIDEO_MAX_PLANES, otherwise the Tegra libv4l2 will write data beyond
  // the number of allocated planes, resulting in memory corruption.
  struct v4l2_plane v4l2_planes_[VIDEO_MAX_PLANES];

 private:
  size_t BufferId() const { return v4l2_buffer_.index; }

  // The queue must be kept alive as long as the reference to the buffer exists.
  scoped_refptr<V4L2Queue> queue_;

  DISALLOW_COPY_AND_ASSIGN(V4L2BufferQueueProxy);
};

V4L2BufferQueueProxy::V4L2BufferQueueProxy(
    const struct v4l2_buffer* v4l2_buffer,
    scoped_refptr<V4L2Queue> queue)
    : queue_(std::move(queue)) {
  DCHECK(V4L2_TYPE_IS_MULTIPLANAR(v4l2_buffer->type));
  DCHECK_LE(v4l2_buffer->length, base::size(v4l2_planes_));

  memcpy(&v4l2_buffer_, v4l2_buffer, sizeof(v4l2_buffer_));
  memcpy(v4l2_planes_, v4l2_buffer->m.planes,
         sizeof(struct v4l2_plane) * v4l2_buffer->length);
  v4l2_buffer_.m.planes = v4l2_planes_;
}

bool V4L2BufferQueueProxy::QueueBuffer() {
  bool queued = queue_->QueueBuffer(&v4l2_buffer_);

  // If an error occurred during queueing, then the buffer must be made
  // available again.
  if (!queued)
    ReturnBuffer();

  return queued;
}

V4L2WritableBufferRef::V4L2WritableBufferRef() {
  // Invalid buffers can be created from any thread.
  DETACH_FROM_SEQUENCE(sequence_checker_);
}

V4L2WritableBufferRef::V4L2WritableBufferRef(
    const struct v4l2_buffer* v4l2_buffer,
    scoped_refptr<V4L2Queue> queue)
    : buffer_data_(std::make_unique<V4L2BufferQueueProxy>(v4l2_buffer,
                                                          std::move(queue))) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
}

V4L2WritableBufferRef::V4L2WritableBufferRef(V4L2WritableBufferRef&& other)
    : buffer_data_(std::move(other.buffer_data_)) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK_CALLED_ON_VALID_SEQUENCE(other.sequence_checker_);
}

V4L2WritableBufferRef::~V4L2WritableBufferRef() {
  // Only valid references should be sequence-checked
  if (buffer_data_) {
    DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
    buffer_data_->ReturnBuffer();
  }
}

V4L2WritableBufferRef& V4L2WritableBufferRef::operator=(
    V4L2WritableBufferRef&& other) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK_CALLED_ON_VALID_SEQUENCE(other.sequence_checker_);

  if (this == &other)
    return *this;

  if (IsValid())
    buffer_data_->ReturnBuffer();
  buffer_data_ = std::move(other.buffer_data_);

  return *this;
}

bool V4L2WritableBufferRef::IsValid() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  return buffer_data_ != nullptr;
}

enum v4l2_memory V4L2WritableBufferRef::Memory() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(IsValid());

  return static_cast<enum v4l2_memory>(buffer_data_->v4l2_buffer_.memory);
}

bool V4L2WritableBufferRef::DoQueue() && {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(IsValid());

  bool queued = buffer_data_->QueueBuffer();

  // Clear our own reference.
  buffer_data_.reset();

  return queued;
}

bool V4L2WritableBufferRef::QueueMMap() && {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(IsValid());

  // Move ourselves so our data gets freed no matter when we return
  V4L2WritableBufferRef self(std::move(*this));

  if (self.Memory() != V4L2_MEMORY_MMAP) {
    VLOGF(1) << "Called on invalid buffer type!";
    return false;
  }

  return std::move(self).DoQueue();
}

bool V4L2WritableBufferRef::QueueUserPtr(const std::vector<void*>& ptrs) && {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(IsValid());

  // Move ourselves so our data gets freed no matter when we return
  V4L2WritableBufferRef self(std::move(*this));

  if (self.Memory() != V4L2_MEMORY_USERPTR) {
    VLOGF(1) << "Called on invalid buffer type!";
    return false;
  }

  if (ptrs.size() != self.PlanesCount()) {
    VLOGF(1) << "Provided " << ptrs.size() << " pointers while we require "
             << self.buffer_data_->v4l2_buffer_.length << ".";
    return false;
  }

  for (size_t i = 0; i < ptrs.size(); i++)
    self.buffer_data_->v4l2_buffer_.m.planes[i].m.userptr =
        reinterpret_cast<unsigned long>(ptrs[i]);

  return std::move(self).DoQueue();
}

bool V4L2WritableBufferRef::QueueDMABuf(
    const std::vector<base::ScopedFD>& fds) && {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(IsValid());

  // Move ourselves so our data gets freed no matter when we return
  V4L2WritableBufferRef self(std::move(*this));

  if (self.Memory() != V4L2_MEMORY_DMABUF) {
    VLOGF(1) << "Called on invalid buffer type!";
    return false;
  }

  if (fds.size() != self.PlanesCount()) {
    VLOGF(1) << "Provided " << fds.size() << " FDs while we require "
             << self.buffer_data_->v4l2_buffer_.length << ".";
    return false;
  }

  for (size_t i = 0; i < fds.size(); i++)
    self.buffer_data_->v4l2_buffer_.m.planes[i].m.fd = fds[i].get();

  return std::move(self).DoQueue();
}

size_t V4L2WritableBufferRef::PlanesCount() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(IsValid());

  return buffer_data_->v4l2_buffer_.length;
}

size_t V4L2WritableBufferRef::GetPlaneSize(const size_t plane) const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(IsValid());

  if (plane >= PlanesCount()) {
    VLOGF(1) << "Invalid plane " << plane << " requested.";
    return 0;
  }

  return buffer_data_->v4l2_buffer_.m.planes[plane].length;
}

void* V4L2WritableBufferRef::GetPlaneMapping(const size_t plane) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(IsValid());

  return buffer_data_->GetPlaneMapping(plane);
}

void V4L2WritableBufferRef::SetTimeStamp(const struct timeval& timestamp) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(IsValid());

  buffer_data_->v4l2_buffer_.timestamp = timestamp;
}

const struct timeval& V4L2WritableBufferRef::GetTimeStamp() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(IsValid());

  return buffer_data_->v4l2_buffer_.timestamp;
}

void V4L2WritableBufferRef::SetPlaneBytesUsed(const size_t plane,
                                              const size_t bytes_used) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(IsValid());

  if (plane >= PlanesCount()) {
    VLOGF(1) << "Invalid plane " << plane << " requested.";
    return;
  }

  if (bytes_used >= GetPlaneSize(plane)) {
    VLOGF(1) << "Set bytes used " << bytes_used << " larger than plane size "
             << GetPlaneSize(plane) << ".";
    return;
  }

  buffer_data_->v4l2_buffer_.m.planes[plane].bytesused = bytes_used;
}

size_t V4L2WritableBufferRef::GetPlaneBytesUsed(const size_t plane) const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(IsValid());

  if (plane >= PlanesCount()) {
    VLOGF(1) << "Invalid plane " << plane << " requested.";
    return 0;
  }

  return buffer_data_->v4l2_buffer_.m.planes[plane].bytesused;
}

size_t V4L2WritableBufferRef::BufferId() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(IsValid());

  return buffer_data_->v4l2_buffer_.index;
}

V4L2ReadableBuffer::V4L2ReadableBuffer(const struct v4l2_buffer* v4l2_buffer,
                                       scoped_refptr<V4L2Queue> queue)
    : buffer_data_(std::make_unique<V4L2BufferQueueProxy>(v4l2_buffer,
                                                          std::move(queue))) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
}

V4L2ReadableBuffer::~V4L2ReadableBuffer() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(buffer_data_);

  buffer_data_->ReturnBuffer();
}

bool V4L2ReadableBuffer::IsLast() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(buffer_data_);

  return buffer_data_->v4l2_buffer_.flags & V4L2_BUF_FLAG_LAST;
}

struct timeval V4L2ReadableBuffer::GetTimeStamp() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(buffer_data_);

  return buffer_data_->v4l2_buffer_.timestamp;
}

size_t V4L2ReadableBuffer::PlanesCount() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(buffer_data_);

  return buffer_data_->v4l2_buffer_.length;
}

size_t V4L2ReadableBuffer::GetPlaneBytesUsed(const size_t plane) const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(buffer_data_);

  if (plane >= PlanesCount()) {
    VLOGF(1) << "Invalid plane " << plane << " requested.";
    return 0;
  }

  return buffer_data_->v4l2_planes_[plane].bytesused;
}

size_t V4L2ReadableBuffer::BufferId() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK(buffer_data_);

  return buffer_data_->v4l2_buffer_.index;
}

// This class is used to expose buffer reference classes constructors to
// this module. This is to ensure that nobody else can create buffer references.
class V4L2BufferRefFactory {
 public:
  static V4L2WritableBufferRef CreateWritableRef(
      const struct v4l2_buffer* v4l2_buffer,
      scoped_refptr<V4L2Queue> queue) {
    return V4L2WritableBufferRef(v4l2_buffer, std::move(queue));
  }

  static V4L2ReadableBufferRef CreateReadableRef(
      const struct v4l2_buffer* v4l2_buffer,
      scoped_refptr<V4L2Queue> queue) {
    return new V4L2ReadableBuffer(v4l2_buffer, std::move(queue));
  }
};

V4L2Queue::V4L2Queue(scoped_refptr<V4L2Device> dev,
                     enum v4l2_buf_type type,
                     base::OnceClosure destroy_cb)
    : type_(type), device_(dev), destroy_cb_(std::move(destroy_cb)) {
  // TODO(acourbot): fix clients - the constructor should be called on the same
  // sequence as the rest.
  DETACH_FROM_SEQUENCE(sequence_checker_);
}

V4L2Queue::~V4L2Queue() {
  // TODO(acourbot): we do this prior to checking the sequence because we
  // tolerate queues to be destroyed in the wrong thread if they are properly
  // cleaned up. But ultimately clients should be fixed.
  if (!is_streaming_ && buffers_.empty()) {
    std::move(destroy_cb_).Run();
    return;
  }

  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  if (is_streaming_) {
    VLOGF(1) << "Queue is still streaming, trying to stop it...";
    Streamoff();
  }

  DCHECK(queued_buffers_.empty());
  DCHECK(free_buffers_.empty());

  if (!buffers_.empty()) {
    VLOGF(1) << "Buffers are still allocated, trying to deallocate them...";
    DeallocateBuffers();
  }

  std::move(destroy_cb_).Run();
}

size_t V4L2Queue::AllocateBuffers(size_t count, enum v4l2_memory memory) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  DCHECK_EQ(free_buffers_.size(), 0u);
  DCHECK_EQ(queued_buffers_.size(), 0u);

  if (IsStreaming()) {
    VLOGF(1) << "Cannot allocate buffers while streaming.";
    return 0;
  }

  if (buffers_.size() != 0) {
    VLOGF(1) << "Cannot allocate new buffers while others are still allocated.";
    return 0;
  }

  if (count == 0) {
    VLOGF(1) << "Attempting to allocate 0 buffers.";
    return 0;
  }

  // First query the number of planes in the buffers we are about to request.
  // This should not be required, but Tegra's VIDIOC_QUERYBUF will fail on
  // output buffers if the number of specified planes does not exactly match the
  // format.
  struct v4l2_format format = {.type = type_};
  int ret = device_->Ioctl(VIDIOC_G_FMT, &format);
  if (ret) {
    VPLOGF(1) << "VIDIOC_G_FMT failed: ";
    return 0;
  }
  planes_count_ = format.fmt.pix_mp.num_planes;
  DCHECK_LE(planes_count_, static_cast<size_t>(VIDEO_MAX_PLANES));

  struct v4l2_requestbuffers reqbufs = {};
  reqbufs.count = count;
  reqbufs.type = type_;
  reqbufs.memory = memory;
  DVLOGF(3) << "queue " << type_ << ": requesting " << count << " buffers.";

  ret = device_->Ioctl(VIDIOC_REQBUFS, &reqbufs);
  if (ret) {
    VPLOGF(1) << "VIDIOC_REQBUFS failed: ";
    return 0;
  }
  DVLOGF(3) << "queue " << type_ << ": got " << reqbufs.count << " buffers.";

  memory_ = memory;

  // Now query all buffer information.
  for (size_t i = 0; i < reqbufs.count; i++) {
    auto buffer = V4L2Buffer::Create(device_, type_, memory_, planes_count_, i);

    if (!buffer) {
      DeallocateBuffers();

      return 0;
    }

    buffers_.emplace_back(std::move(buffer));
    ReturnBuffer(i);
  }

  DCHECK_EQ(free_buffers_.size(), buffers_.size());
  DCHECK_EQ(queued_buffers_.size(), 0u);

  return buffers_.size();
}

bool V4L2Queue::DeallocateBuffers() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  if (IsStreaming()) {
    VLOGF(1) << "Cannot deallocate buffers while streaming.";
    return false;
  }

  if (buffers_.size() != free_buffers_.size()) {
    VPLOGF(1) << "Trying to deallocate buffers while some are still in use!";
    return false;
  }

  if (buffers_.size() == 0)
    return true;

  // Free all buffers.
  struct v4l2_requestbuffers reqbufs = {};
  reqbufs.count = 0;
  reqbufs.type = type_;
  reqbufs.memory = memory_;

  int ret = device_->Ioctl(VIDIOC_REQBUFS, &reqbufs);
  if (ret) {
    VPLOGF(1) << "VIDIOC_REQBUFS failed: ";
    return false;
  }

  buffers_.clear();
  free_buffers_.clear();

  DCHECK_EQ(free_buffers_.size(), 0u);
  DCHECK_EQ(queued_buffers_.size(), 0u);

  return true;
}

size_t V4L2Queue::GetMemoryUsage() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  size_t usage = 0;
  for (const auto& buf : buffers_) {
    usage += buf->GetMemoryUsage();
  }
  return usage;
}

v4l2_memory V4L2Queue::GetMemoryType() const {
  return memory_;
}

V4L2WritableBufferRef V4L2Queue::GetFreeBuffer() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
  auto iter = free_buffers_.begin();

  if (iter == free_buffers_.end()) {
    VLOGF(3) << "No free buffer available!";
    return V4L2WritableBufferRef();
  }

  size_t buffer_id = *iter;
  free_buffers_.erase(buffer_id);

  return V4L2BufferRefFactory::CreateWritableRef(
      buffers_[buffer_id]->v4l2_buffer(), this);
}

void V4L2Queue::ReturnBuffer(size_t buffer_id) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  auto inserted = free_buffers_.emplace(buffer_id);
  DCHECK_EQ(inserted.second, true);
}

bool V4L2Queue::QueueBuffer(struct v4l2_buffer* v4l2_buffer) {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  int ret = device_->Ioctl(VIDIOC_QBUF, v4l2_buffer);
  if (ret) {
    VPLOGF(1) << "VIDIOC_QBUF failed: ";
    return false;
  }

  auto inserted = queued_buffers_.emplace(v4l2_buffer->index);
  DCHECK_EQ(inserted.second, true);

  return true;
}

std::pair<bool, V4L2ReadableBufferRef> V4L2Queue::DequeueBuffer() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  // No need to dequeue if no buffers queued.
  if (QueuedBuffersCount() == 0)
    return std::make_pair(true, nullptr);

  if (!IsStreaming()) {
    VLOGF(1) << "Attempting to dequeue a buffer while not streaming.";
    return std::make_pair(true, nullptr);
  }

  struct v4l2_buffer v4l2_buffer = {};
  // WARNING: do not change this to a vector or something smaller than
  // VIDEO_MAX_PLANES, otherwise the Tegra libv4l2 will write data beyond
  // the number of allocated planes, resulting in memory corruption.
  struct v4l2_plane planes[VIDEO_MAX_PLANES] = {{}};
  v4l2_buffer.type = type_;
  v4l2_buffer.memory = memory_;
  v4l2_buffer.m.planes = planes;
  v4l2_buffer.length = planes_count_;
  int ret = device_->Ioctl(VIDIOC_DQBUF, &v4l2_buffer);
  if (ret) {
    // TODO(acourbot): we should not have to check for EPIPE as codec clients
    // should not call this method after the last buffer is dequeued.
    switch (errno) {
      case EAGAIN:
      case EPIPE:
        // This is not an error but won't provide a buffer either.
        return std::make_pair(true, nullptr);
      default:
        VPLOGF(1) << "VIDIOC_DQBUF failed: ";
        return std::make_pair(false, nullptr);
    }
  }

  auto it = queued_buffers_.find(v4l2_buffer.index);
  DCHECK(it != queued_buffers_.end());
  queued_buffers_.erase(*it);

  return std::make_pair(
      true, V4L2BufferRefFactory::CreateReadableRef(&v4l2_buffer, this));
}

bool V4L2Queue::IsStreaming() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  return is_streaming_;
}

bool V4L2Queue::Streamon() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  if (is_streaming_)
    return true;

  int arg = static_cast<int>(type_);
  int ret = device_->Ioctl(VIDIOC_STREAMON, &arg);
  if (ret) {
    VPLOGF(1) << "VIDIOC_STREAMON failed: ";
    return false;
  }

  is_streaming_ = true;

  return true;
}

bool V4L2Queue::Streamoff() {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  // We do not check the value of IsStreaming(), because we may have queued
  // buffers to the queue and wish to get them back - in such as case, we may
  // need to do a VIDIOC_STREAMOFF on a stopped queue.

  int arg = static_cast<int>(type_);
  int ret = device_->Ioctl(VIDIOC_STREAMOFF, &arg);
  if (ret) {
    VPLOGF(1) << "VIDIOC_STREAMOFF failed: ";
    return false;
  }

  for (const auto& buffer_id : queued_buffers_)
    ReturnBuffer(buffer_id);

  queued_buffers_.clear();

  is_streaming_ = false;

  return true;
}

size_t V4L2Queue::AllocatedBuffersCount() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  return buffers_.size();
}

size_t V4L2Queue::FreeBuffersCount() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  return free_buffers_.size();
}

size_t V4L2Queue::QueuedBuffersCount() const {
  DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

  return queued_buffers_.size();
}

// This class is used to expose V4L2Queue's constructor to this module. This is
// to ensure that nobody else can create instances of it.
class V4L2QueueFactory {
 public:
  static scoped_refptr<V4L2Queue> CreateQueue(scoped_refptr<V4L2Device> dev,
                                              enum v4l2_buf_type type,
                                              base::OnceClosure destroy_cb) {
    return new V4L2Queue(std::move(dev), type, std::move(destroy_cb));
  }
};

V4L2Device::V4L2Device() {}

V4L2Device::~V4L2Device() {}

scoped_refptr<V4L2Queue> V4L2Device::GetQueue(enum v4l2_buf_type type) {
  switch (type) {
    // Supported queue types.
    case V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE:
    case V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE:
      break;
    default:
      VLOGF(1) << "Unsupported V4L2 queue type: " << type;
      return nullptr;
  }

  // TODO(acourbot): we should instead query the device for available queues,
  // and allocate them accordingly. This will do for now though.
  auto it = queues_.find(type);
  if (it != queues_.end())
    return scoped_refptr<V4L2Queue>(it->second);

  scoped_refptr<V4L2Queue> queue = V4L2QueueFactory::CreateQueue(
      this, type,
      media::BindToCurrentLoop(
          base::Bind(&V4L2Device::OnQueueDestroyed, this, type)));

  queues_[type] = queue.get();
  return queue;
}

void V4L2Device::OnQueueDestroyed(v4l2_buf_type buf_type) {
  auto it = queues_.find(buf_type);
  DCHECK(it != queues_.end());
  queues_.erase(it);
}

// static
scoped_refptr<V4L2Device> V4L2Device::Create() {
  VLOGF(2);

  scoped_refptr<V4L2Device> device;

#if defined(ARCH_CPU_ARMEL)
  device = new TegraV4L2Device();
  if (device->Initialize())
    return device;
#endif

  device = new GenericV4L2Device();
  if (device->Initialize())
    return device;

  VLOGF(1) << "Failed to create a V4L2Device";
  return nullptr;
}

// static
VideoPixelFormat V4L2Device::V4L2PixFmtToVideoPixelFormat(uint32_t pix_fmt) {
  switch (pix_fmt) {
    case V4L2_PIX_FMT_NV12:
    case V4L2_PIX_FMT_NV12M:
      return PIXEL_FORMAT_NV12;

    case V4L2_PIX_FMT_MT21C:
      return PIXEL_FORMAT_MT21;

    case V4L2_PIX_FMT_YUV420:
    case V4L2_PIX_FMT_YUV420M:
      return PIXEL_FORMAT_I420;

    case V4L2_PIX_FMT_YVU420:
    case V4L2_PIX_FMT_YVU420M:
      return PIXEL_FORMAT_YV12;

    case V4L2_PIX_FMT_YUV422M:
      return PIXEL_FORMAT_I422;

    case V4L2_PIX_FMT_RGB32:
      return PIXEL_FORMAT_ARGB;

    default:
      DVLOGF(1) << "Add more cases as needed";
      return PIXEL_FORMAT_UNKNOWN;
  }
}

// static
uint32_t V4L2Device::VideoPixelFormatToV4L2PixFmt(const VideoPixelFormat format,
                                                  bool single_planar) {
  switch (format) {
    case PIXEL_FORMAT_NV12:
      return single_planar ? V4L2_PIX_FMT_NV12 : V4L2_PIX_FMT_NV12M;
    case PIXEL_FORMAT_MT21:
      // No single plane format for MT21.
      return single_planar ? 0 : V4L2_PIX_FMT_MT21C;
    case PIXEL_FORMAT_I420:
      return single_planar ? V4L2_PIX_FMT_YUV420 : V4L2_PIX_FMT_YUV420M;
    case PIXEL_FORMAT_YV12:
      return single_planar ? V4L2_PIX_FMT_YVU420 : V4L2_PIX_FMT_YVU420M;
    default:
      LOG(FATAL) << "Add more cases as needed";
      return 0;
  }
}

// static
uint32_t V4L2Device::VideoFrameLayoutToV4L2PixFmt(
    const VideoFrameLayout& layout) {
  if (layout.num_buffers() == 0) {
    VLOGF(1) << "layout.num_buffers() must be more than 0: " << layout;
    return 0;
  }
  return VideoPixelFormatToV4L2PixFmt(layout.format(),
                                      layout.num_buffers() == 1);
}

// static
uint32_t V4L2Device::VideoCodecProfileToV4L2PixFmt(VideoCodecProfile profile,
                                                   bool slice_based) {
  if (profile >= H264PROFILE_MIN && profile <= H264PROFILE_MAX) {
    if (slice_based)
      return V4L2_PIX_FMT_H264_SLICE;
    else
      return V4L2_PIX_FMT_H264;
  } else if (profile >= VP8PROFILE_MIN && profile <= VP8PROFILE_MAX) {
    if (slice_based)
      return V4L2_PIX_FMT_VP8_FRAME;
    else
      return V4L2_PIX_FMT_VP8;
  } else if (profile >= VP9PROFILE_MIN && profile <= VP9PROFILE_MAX) {
    if (slice_based)
      return V4L2_PIX_FMT_VP9_FRAME;
    else
      return V4L2_PIX_FMT_VP9;
  } else {
    LOG(FATAL) << "Add more cases as needed";
    return 0;
  }
}

// static
VideoCodecProfile V4L2Device::V4L2VP9ProfileToVideoCodecProfile(
    uint32_t profile) {
  switch (profile) {
    case V4L2_MPEG_VIDEO_VP9_PROFILE_0:
      return VP9PROFILE_PROFILE0;
    case V4L2_MPEG_VIDEO_VP9_PROFILE_1:
      return VP9PROFILE_PROFILE1;
    case V4L2_MPEG_VIDEO_VP9_PROFILE_2:
      return VP9PROFILE_PROFILE2;
    case V4L2_MPEG_VIDEO_VP9_PROFILE_3:
      return VP9PROFILE_PROFILE3;
    default:
      VLOGF(2) << "Not a VP9 profile: " << profile;
      return VIDEO_CODEC_PROFILE_UNKNOWN;
  }
}

// static
std::vector<VideoCodecProfile> V4L2Device::V4L2PixFmtToVideoCodecProfiles(
    uint32_t pix_fmt,
    bool is_encoder) {
  VideoCodecProfile min_profile, max_profile;
  std::vector<VideoCodecProfile> profiles;

  switch (pix_fmt) {
    case V4L2_PIX_FMT_H264:
    case V4L2_PIX_FMT_H264_SLICE:
      if (is_encoder) {
        // TODO(posciak): need to query the device for supported H.264 profiles,
        // for now choose Main as a sensible default.
        min_profile = H264PROFILE_MAIN;
        max_profile = H264PROFILE_MAIN;
      } else {
        min_profile = H264PROFILE_MIN;
        max_profile = H264PROFILE_MAX;
      }
      break;

    case V4L2_PIX_FMT_VP8:
    case V4L2_PIX_FMT_VP8_FRAME:
      min_profile = VP8PROFILE_MIN;
      max_profile = VP8PROFILE_MAX;
      break;

    case V4L2_PIX_FMT_VP9:
    case V4L2_PIX_FMT_VP9_FRAME: {
      v4l2_queryctrl query_ctrl = {};
      query_ctrl.id = V4L2_CID_MPEG_VIDEO_VP9_PROFILE;
      if (Ioctl(VIDIOC_QUERYCTRL, &query_ctrl) == 0) {
        v4l2_querymenu query_menu = {};
        query_menu.id = query_ctrl.id;
        for (query_menu.index = query_ctrl.minimum;
             static_cast<int>(query_menu.index) <= query_ctrl.maximum;
             query_menu.index++) {
          if (Ioctl(VIDIOC_QUERYMENU, &query_menu) == 0) {
            const VideoCodecProfile profile =
                V4L2VP9ProfileToVideoCodecProfile(query_menu.index);
            if (profile != VIDEO_CODEC_PROFILE_UNKNOWN)
              profiles.push_back(profile);
          }
        }
        return profiles;
      } else {
        // TODO(keiichiw): need a fallback here?
        VLOGF(2) << "V4L2_CID_MPEG_VIDEO_VP9_PROFILE is not supported.";
        min_profile = VP9PROFILE_PROFILE0;
        max_profile = VP9PROFILE_PROFILE0;
      }
      break;
    }

    default:
      VLOGF(1) << "Unhandled pixelformat " << FourccToString(pix_fmt);
      return profiles;
  }

  for (int profile = min_profile; profile <= max_profile; ++profile)
    profiles.push_back(static_cast<VideoCodecProfile>(profile));

  return profiles;
}

// static
uint32_t V4L2Device::V4L2PixFmtToDrmFormat(uint32_t format) {
  switch (format) {
    case V4L2_PIX_FMT_NV12:
    case V4L2_PIX_FMT_NV12M:
      return DRM_FORMAT_NV12;

    case V4L2_PIX_FMT_YUV420:
    case V4L2_PIX_FMT_YUV420M:
      return DRM_FORMAT_YUV420;

    case V4L2_PIX_FMT_YVU420:
      return DRM_FORMAT_YVU420;

    case V4L2_PIX_FMT_RGB32:
      return DRM_FORMAT_ARGB8888;

    case V4L2_PIX_FMT_MT21C:
      return DRM_FORMAT_MT21;

    default:
      DVLOGF(1) << "Unrecognized format " << FourccToString(format);
      return 0;
  }
}

// static
int32_t V4L2Device::VideoCodecProfileToV4L2H264Profile(
    VideoCodecProfile profile) {
  switch (profile) {
    case H264PROFILE_BASELINE:
      return V4L2_MPEG_VIDEO_H264_PROFILE_BASELINE;
    case H264PROFILE_MAIN:
      return V4L2_MPEG_VIDEO_H264_PROFILE_MAIN;
    case H264PROFILE_EXTENDED:
      return V4L2_MPEG_VIDEO_H264_PROFILE_EXTENDED;
    case H264PROFILE_HIGH:
      return V4L2_MPEG_VIDEO_H264_PROFILE_HIGH;
    case H264PROFILE_HIGH10PROFILE:
      return V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_10;
    case H264PROFILE_HIGH422PROFILE:
      return V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_422;
    case H264PROFILE_HIGH444PREDICTIVEPROFILE:
      return V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_444_PREDICTIVE;
    case H264PROFILE_SCALABLEBASELINE:
      return V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_BASELINE;
    case H264PROFILE_SCALABLEHIGH:
      return V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_HIGH;
    case H264PROFILE_STEREOHIGH:
      return V4L2_MPEG_VIDEO_H264_PROFILE_STEREO_HIGH;
    case H264PROFILE_MULTIVIEWHIGH:
      return V4L2_MPEG_VIDEO_H264_PROFILE_MULTIVIEW_HIGH;
    default:
      DVLOGF(1) << "Add more cases as needed";
      return -1;
  }
}

// static
int32_t V4L2Device::H264LevelIdcToV4L2H264Level(uint8_t level_idc) {
  switch (level_idc) {
    case 10:
      return V4L2_MPEG_VIDEO_H264_LEVEL_1_0;
    case 9:
      return V4L2_MPEG_VIDEO_H264_LEVEL_1B;
    case 11:
      return V4L2_MPEG_VIDEO_H264_LEVEL_1_1;
    case 12:
      return V4L2_MPEG_VIDEO_H264_LEVEL_1_2;
    case 13:
      return V4L2_MPEG_VIDEO_H264_LEVEL_1_3;
    case 20:
      return V4L2_MPEG_VIDEO_H264_LEVEL_2_0;
    case 21:
      return V4L2_MPEG_VIDEO_H264_LEVEL_2_1;
    case 22:
      return V4L2_MPEG_VIDEO_H264_LEVEL_2_2;
    case 30:
      return V4L2_MPEG_VIDEO_H264_LEVEL_3_0;
    case 31:
      return V4L2_MPEG_VIDEO_H264_LEVEL_3_1;
    case 32:
      return V4L2_MPEG_VIDEO_H264_LEVEL_3_2;
    case 40:
      return V4L2_MPEG_VIDEO_H264_LEVEL_4_0;
    case 41:
      return V4L2_MPEG_VIDEO_H264_LEVEL_4_1;
    case 42:
      return V4L2_MPEG_VIDEO_H264_LEVEL_4_2;
    case 50:
      return V4L2_MPEG_VIDEO_H264_LEVEL_5_0;
    case 51:
      return V4L2_MPEG_VIDEO_H264_LEVEL_5_1;
    default:
      DVLOGF(1) << "Unrecognized level_idc: " << static_cast<int>(level_idc);
      return -1;
  }
}

// static
gfx::Size V4L2Device::AllocatedSizeFromV4L2Format(struct v4l2_format format) {
  gfx::Size coded_size;
  gfx::Size visible_size;
  VideoPixelFormat frame_format = PIXEL_FORMAT_UNKNOWN;
  size_t bytesperline = 0;
  // Total bytes in the frame.
  size_t sizeimage = 0;

  if (V4L2_TYPE_IS_MULTIPLANAR(format.type)) {
    DCHECK_GT(format.fmt.pix_mp.num_planes, 0);
    bytesperline =
        base::checked_cast<int>(format.fmt.pix_mp.plane_fmt[0].bytesperline);
    for (size_t i = 0; i < format.fmt.pix_mp.num_planes; ++i) {
      sizeimage +=
          base::checked_cast<int>(format.fmt.pix_mp.plane_fmt[i].sizeimage);
    }
    visible_size.SetSize(base::checked_cast<int>(format.fmt.pix_mp.width),
                         base::checked_cast<int>(format.fmt.pix_mp.height));
    frame_format =
        V4L2Device::V4L2PixFmtToVideoPixelFormat(format.fmt.pix_mp.pixelformat);
  } else {
    bytesperline = base::checked_cast<int>(format.fmt.pix.bytesperline);
    sizeimage = base::checked_cast<int>(format.fmt.pix.sizeimage);
    visible_size.SetSize(base::checked_cast<int>(format.fmt.pix.width),
                         base::checked_cast<int>(format.fmt.pix.height));
    frame_format =
        V4L2Device::V4L2PixFmtToVideoPixelFormat(format.fmt.pix.pixelformat);
  }

  // V4L2 does not provide per-plane bytesperline (bpl) when different
  // components are sharing one physical plane buffer. In this case, it only
  // provides bpl for the first component in the plane. So we can't depend on it
  // for calculating height, because bpl may vary within one physical plane
  // buffer. For example, YUV420 contains 3 components in one physical plane,
  // with Y at 8 bits per pixel, and Cb/Cr at 4 bits per pixel per component,
  // but we only get 8 pits per pixel from bytesperline in physical plane 0.
  // So we need to get total frame bpp from elsewhere to calculate coded height.

  // We need bits per pixel for one component only to calculate
  // coded_width from bytesperline.
  int plane_horiz_bits_per_pixel =
      VideoFrame::PlaneHorizontalBitsPerPixel(frame_format, 0);

  // Adding up bpp for each component will give us total bpp for all components.
  int total_bpp = 0;
  for (size_t i = 0; i < VideoFrame::NumPlanes(frame_format); ++i)
    total_bpp += VideoFrame::PlaneBitsPerPixel(frame_format, i);

  if (sizeimage == 0 || bytesperline == 0 || plane_horiz_bits_per_pixel == 0 ||
      total_bpp == 0 || (bytesperline * 8) % plane_horiz_bits_per_pixel != 0) {
    VLOGF(1) << "Invalid format provided";
    return coded_size;
  }

  // Coded width can be calculated by taking the first component's bytesperline,
  // which in V4L2 always applies to the first component in physical plane
  // buffer.
  int coded_width = bytesperline * 8 / plane_horiz_bits_per_pixel;
  // Sizeimage is coded_width * coded_height * total_bpp.
  int coded_height = sizeimage * 8 / coded_width / total_bpp;

  coded_size.SetSize(coded_width, coded_height);
  DVLOGF(3) << "coded_size=" << coded_size.ToString();

  // Sanity checks. Calculated coded size has to contain given visible size
  // and fulfill buffer byte size requirements.
  DCHECK(gfx::Rect(coded_size).Contains(gfx::Rect(visible_size)));
  DCHECK_LE(sizeimage, VideoFrame::AllocationSize(frame_format, coded_size));

  return coded_size;
}

// static
std::string V4L2Device::V4L2MemoryToString(const v4l2_memory memory) {
  switch (memory) {
    case V4L2_MEMORY_MMAP:
      return "V4L2_MEMORY_MMAP";
    case V4L2_MEMORY_USERPTR:
      return "V4L2_MEMORY_USERPTR";
    case V4L2_MEMORY_DMABUF:
      return "V4L2_MEMORY_DMABUF";
    case V4L2_MEMORY_OVERLAY:
      return "V4L2_MEMORY_OVERLAY";
    default:
      return "UNKNOWN";
  }
}

// static
std::string V4L2Device::V4L2FormatToString(const struct v4l2_format& format) {
  std::ostringstream s;
  s << "v4l2_format type: " << format.type;
  if (format.type == V4L2_BUF_TYPE_VIDEO_CAPTURE ||
      format.type == V4L2_BUF_TYPE_VIDEO_OUTPUT) {
    //  single-planar
    const struct v4l2_pix_format& pix = format.fmt.pix;
    s << ", width_height: " << gfx::Size(pix.width, pix.height).ToString()
      << ", pixelformat: " << FourccToString(pix.pixelformat)
      << ", field: " << pix.field << ", bytesperline: " << pix.bytesperline
      << ", sizeimage: " << pix.sizeimage;
  } else if (V4L2_TYPE_IS_MULTIPLANAR(format.type)) {
    const struct v4l2_pix_format_mplane& pix_mp = format.fmt.pix_mp;
    // As long as num_planes's type is uint8_t, ostringstream treats it as a
    // char instead of an integer, which is not what we want. Casting
    // pix_mp.num_planes unsigned int solves the issue.
    s << ", width_height: " << gfx::Size(pix_mp.width, pix_mp.height).ToString()
      << ", pixelformat: " << FourccToString(pix_mp.pixelformat)
      << ", field: " << pix_mp.field
      << ", num_planes: " << static_cast<unsigned int>(pix_mp.num_planes);
    for (size_t i = 0; i < pix_mp.num_planes; ++i) {
      const struct v4l2_plane_pix_format& plane_fmt = pix_mp.plane_fmt[i];
      s << ", plane_fmt[" << i << "].sizeimage: " << plane_fmt.sizeimage
        << ", plane_fmt[" << i << "].bytesperline: " << plane_fmt.bytesperline;
    }
  } else {
    s << " unsupported yet.";
  }
  return s.str();
}

// static
std::string V4L2Device::V4L2BufferToString(const struct v4l2_buffer& buffer) {
  std::ostringstream s;
  s << "v4l2_buffer type: " << buffer.type << ", memory: " << buffer.memory
    << ", index: " << buffer.index << " bytesused: " << buffer.bytesused
    << ", length: " << buffer.length;
  if (buffer.type == V4L2_BUF_TYPE_VIDEO_CAPTURE ||
      buffer.type == V4L2_BUF_TYPE_VIDEO_OUTPUT) {
    //  single-planar
    if (buffer.memory == V4L2_MEMORY_MMAP) {
      s << ", m.offset: " << buffer.m.offset;
    } else if (buffer.memory == V4L2_MEMORY_USERPTR) {
      s << ", m.userptr: " << buffer.m.userptr;
    } else if (buffer.memory == V4L2_MEMORY_DMABUF) {
      s << ", m.fd: " << buffer.m.fd;
    }
  } else if (V4L2_TYPE_IS_MULTIPLANAR(buffer.type)) {
    for (size_t i = 0; i < buffer.length; ++i) {
      const struct v4l2_plane& plane = buffer.m.planes[i];
      s << ", m.planes[" << i << "](bytesused: " << plane.bytesused
        << ", length: " << plane.length
        << ", data_offset: " << plane.data_offset;
      if (buffer.memory == V4L2_MEMORY_MMAP) {
        s << ", m.mem_offset: " << plane.m.mem_offset;
      } else if (buffer.memory == V4L2_MEMORY_USERPTR) {
        s << ", m.userptr: " << plane.m.userptr;
      } else if (buffer.memory == V4L2_MEMORY_DMABUF) {
        s << ", m.fd: " << plane.m.fd;
      }
      s << ")";
    }
  } else {
    s << " unsupported yet.";
  }
  return s.str();
}

// static
base::Optional<VideoFrameLayout> V4L2Device::V4L2FormatToVideoFrameLayout(
    const struct v4l2_format& format) {
  if (!V4L2_TYPE_IS_MULTIPLANAR(format.type)) {
    VLOGF(1) << "v4l2_buf_type is not multiplanar: " << std::hex << "0x"
             << format.type;
    return base::nullopt;
  }
  const v4l2_pix_format_mplane& pix_mp = format.fmt.pix_mp;
  const uint32_t& pix_fmt = pix_mp.pixelformat;
  const VideoPixelFormat video_format =
      V4L2Device::V4L2PixFmtToVideoPixelFormat(pix_fmt);
  if (video_format == PIXEL_FORMAT_UNKNOWN) {
    VLOGF(1) << "Failed to convert pixel format to VideoPixelFormat: "
             << FourccToString(pix_fmt);
    return base::nullopt;
  }
  const size_t num_buffers = pix_mp.num_planes;
  const size_t num_color_planes = VideoFrame::NumPlanes(video_format);
  if (num_color_planes == 0) {
    VLOGF(1) << "Unsupported video format for NumPlanes(): "
             << VideoPixelFormatToString(video_format);
    return base::nullopt;
  }
  if (num_buffers > num_color_planes) {
    VLOG(1) << "pix_mp.num_planes: " << num_buffers << " should not be larger "
            << "than NumPlanes(" << VideoPixelFormatToString(video_format)
            << "): " << num_color_planes;
    return base::nullopt;
  }
  // Reserve capacity in advance to prevent unnecessary vector reallocation.
  std::vector<VideoFrameLayout::Plane> planes;
  std::vector<size_t> buffer_sizes;
  planes.reserve(num_color_planes);
  buffer_sizes.reserve(num_buffers);
  for (size_t i = 0; i < num_buffers; ++i) {
    const v4l2_plane_pix_format& plane_format = pix_mp.plane_fmt[i];
    planes.emplace_back(static_cast<int32_t>(plane_format.bytesperline), 0u);
    buffer_sizes.push_back(plane_format.sizeimage);
  }
  // For the case that #color planes > #buffers, it fills stride of color
  // plane which does not map to buffer.
  // Right now only some pixel formats are supported: NV12, YUV420, YVU420.
  if (num_color_planes > num_buffers) {
    const int32_t y_stride = planes[0].stride;
    // Note that y_stride is from v4l2 bytesperline and its type is uint32_t.
    // It is safe to cast to size_t.
    const size_t y_stride_abs = static_cast<size_t>(y_stride);
    switch (pix_fmt) {
      case V4L2_PIX_FMT_NV12:
        // The stride of UV is the same as Y in NV12.
        planes.emplace_back(y_stride, y_stride_abs * pix_mp.height);
        DCHECK_EQ(1u, buffer_sizes.size());
        DCHECK_EQ(2u, planes.size());
        break;
      case V4L2_PIX_FMT_YUV420:
      case V4L2_PIX_FMT_YVU420: {
        // The spec claims that two Cx rows (including padding) is exactly as
        // long as one Y row (including padding). So stride of Y must be even
        // number.
        if (y_stride % 2 != 0 || pix_mp.height % 2 != 0) {
          VLOGF(1) << "Plane-Y stride and height should be even; stride: "
                   << y_stride << ", height: " << pix_mp.height;
          return base::nullopt;
        }
        const int32_t half_stride = y_stride / 2;
        const size_t plane_0_area = y_stride_abs * pix_mp.height;
        const size_t plane_1_area = plane_0_area / 4;
        planes.emplace_back(half_stride, plane_0_area);
        planes.emplace_back(half_stride, plane_0_area + plane_1_area);
        DCHECK_EQ(1u, buffer_sizes.size());
        DCHECK_EQ(3u, planes.size());
        break;
      }
      default:
        VLOGF(1) << "Cannot derive stride for each plane for pixel format "
                 << FourccToString(pix_fmt);
        return base::nullopt;
    }
  }

  // Some V4L2 devices expect buffers to be page-aligned. We cannot detect
  // such devices individually, so set this as a video frame layout property.
  constexpr size_t buffer_alignment = 0x1000;

  return VideoFrameLayout::CreateWithPlanes(
      video_format, gfx::Size(pix_mp.width, pix_mp.height), std::move(planes),
      std::move(buffer_sizes), buffer_alignment);
}

// static
bool V4L2Device::IsMultiPlanarV4L2PixFmt(uint32_t pix_fmt) {
  constexpr uint32_t kMultiV4L2PixFmts[] = {
      V4L2_PIX_FMT_NV12M,
      V4L2_PIX_FMT_MT21C,
      V4L2_PIX_FMT_YUV420M,
      V4L2_PIX_FMT_YVU420M,
  };
  return std::find(std::cbegin(kMultiV4L2PixFmts), std::cend(kMultiV4L2PixFmts),
                   pix_fmt) != std::cend(kMultiV4L2PixFmts);
}

void V4L2Device::GetSupportedResolution(uint32_t pixelformat,
                                        gfx::Size* min_resolution,
                                        gfx::Size* max_resolution) {
  max_resolution->SetSize(0, 0);
  min_resolution->SetSize(0, 0);
  v4l2_frmsizeenum frame_size;
  memset(&frame_size, 0, sizeof(frame_size));
  frame_size.pixel_format = pixelformat;
  for (; Ioctl(VIDIOC_ENUM_FRAMESIZES, &frame_size) == 0; ++frame_size.index) {
    if (frame_size.type == V4L2_FRMSIZE_TYPE_DISCRETE) {
      if (frame_size.discrete.width >=
              base::checked_cast<uint32_t>(max_resolution->width()) &&
          frame_size.discrete.height >=
              base::checked_cast<uint32_t>(max_resolution->height())) {
        max_resolution->SetSize(frame_size.discrete.width,
                                frame_size.discrete.height);
      }
      if (min_resolution->IsEmpty() ||
          (frame_size.discrete.width <=
               base::checked_cast<uint32_t>(min_resolution->width()) &&
           frame_size.discrete.height <=
               base::checked_cast<uint32_t>(min_resolution->height()))) {
        min_resolution->SetSize(frame_size.discrete.width,
                                frame_size.discrete.height);
      }
    } else if (frame_size.type == V4L2_FRMSIZE_TYPE_STEPWISE ||
               frame_size.type == V4L2_FRMSIZE_TYPE_CONTINUOUS) {
      max_resolution->SetSize(frame_size.stepwise.max_width,
                              frame_size.stepwise.max_height);
      min_resolution->SetSize(frame_size.stepwise.min_width,
                              frame_size.stepwise.min_height);
      break;
    }
  }
  if (max_resolution->IsEmpty()) {
    max_resolution->SetSize(1920, 1088);
    VLOGF(1) << "GetSupportedResolution failed to get maximum resolution for "
             << "fourcc " << FourccToString(pixelformat) << ", fall back to "
             << max_resolution->ToString();
  }
  if (min_resolution->IsEmpty()) {
    min_resolution->SetSize(16, 16);
    VLOGF(1) << "GetSupportedResolution failed to get minimum resolution for "
             << "fourcc " << FourccToString(pixelformat) << ", fall back to "
             << min_resolution->ToString();
  }
}

std::vector<uint32_t> V4L2Device::EnumerateSupportedPixelformats(
    v4l2_buf_type buf_type) {
  std::vector<uint32_t> pixelformats;

  v4l2_fmtdesc fmtdesc;
  memset(&fmtdesc, 0, sizeof(fmtdesc));
  fmtdesc.type = buf_type;

  for (; Ioctl(VIDIOC_ENUM_FMT, &fmtdesc) == 0; ++fmtdesc.index) {
    DVLOGF(3) << "Found " << fmtdesc.description << std::hex << " (0x"
              << fmtdesc.pixelformat << ")";
    pixelformats.push_back(fmtdesc.pixelformat);
  }

  return pixelformats;
}

VideoDecodeAccelerator::SupportedProfiles
V4L2Device::EnumerateSupportedDecodeProfiles(const size_t num_formats,
                                             const uint32_t pixelformats[]) {
  VideoDecodeAccelerator::SupportedProfiles profiles;

  const auto& supported_pixelformats =
      EnumerateSupportedPixelformats(V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE);

  for (uint32_t pixelformat : supported_pixelformats) {
    if (std::find(pixelformats, pixelformats + num_formats, pixelformat) ==
        pixelformats + num_formats)
      continue;

    VideoDecodeAccelerator::SupportedProfile profile;
    GetSupportedResolution(pixelformat, &profile.min_resolution,
                           &profile.max_resolution);

    const auto video_codec_profiles =
        V4L2PixFmtToVideoCodecProfiles(pixelformat, false);

    for (const auto& video_codec_profile : video_codec_profiles) {
      profile.profile = video_codec_profile;
      profiles.push_back(profile);

      DVLOGF(3) << "Found decoder profile " << GetProfileName(profile.profile)
                << ", resolutions: " << profile.min_resolution.ToString() << " "
                << profile.max_resolution.ToString();
    }
  }

  return profiles;
}

VideoEncodeAccelerator::SupportedProfiles
V4L2Device::EnumerateSupportedEncodeProfiles() {
  VideoEncodeAccelerator::SupportedProfiles profiles;

  const auto& supported_pixelformats =
      EnumerateSupportedPixelformats(V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE);

  for (const auto& pixelformat : supported_pixelformats) {
    VideoEncodeAccelerator::SupportedProfile profile;
    profile.max_framerate_numerator = 30;
    profile.max_framerate_denominator = 1;
    gfx::Size min_resolution;
    GetSupportedResolution(pixelformat, &min_resolution,
                           &profile.max_resolution);

    const auto video_codec_profiles =
        V4L2PixFmtToVideoCodecProfiles(pixelformat, true);

    for (const auto& video_codec_profile : video_codec_profiles) {
      profile.profile = video_codec_profile;
      profiles.push_back(profile);

      DVLOGF(3) << "Found encoder profile " << GetProfileName(profile.profile)
                << ", max resolution: " << profile.max_resolution.ToString();
    }
  }

  return profiles;
}

}  //  namespace media