blob: c26e5976b5d6dce1a35e4a9f359cf30367b09f9f [file] [log] [blame]
// Copyright (c) 2012 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.
// VideoCaptureDevice is the abstract base class for realizing video capture
// device support in Chromium. It provides the interface for OS dependent
// implementations.
// The class is created and functions are invoked on a thread owned by
// VideoCaptureManager. Capturing is done on other threads, depending on the OS
// specific implementation.
#include <stddef.h>
#include <stdint.h>
#include <list>
#include <memory>
#include <string>
#include "base/callback.h"
#include "base/files/file.h"
#include "base/logging.h"
#include "base/memory/ref_counted.h"
#include "base/single_thread_task_runner.h"
#include "base/time/time.h"
#include "build/build_config.h"
#include "media/base/video_frame.h"
#include "media/capture/capture_export.h"
#include "media/capture/mojo/image_capture.mojom.h"
#include "media/capture/video/video_capture_buffer_handle.h"
#include "media/capture/video/video_capture_device_descriptor.h"
#include "media/capture/video_capture_types.h"
#include "ui/gfx/gpu_memory_buffer.h"
namespace base {
class Location;
} // namespace base
namespace media {
class CAPTURE_EXPORT VideoFrameConsumerFeedbackObserver {
virtual ~VideoFrameConsumerFeedbackObserver() {}
// During processing of a video frame, consumers may report back their
// utilization level to the source device. The device may use this information
// to adjust the rate of data it pushes out. Values are interpreted as
// follows:
// Less than 0.0 is meaningless and should be ignored. 1.0 indicates a
// maximum sustainable utilization. Greater than 1.0 indicates the consumer
// is likely to stall or drop frames if the data volume is not reduced.
// Example: In a system that encodes and transmits video frames over the
// network, this value can be used to indicate whether sufficient CPU
// is available for encoding and/or sufficient bandwidth is available for
// transmission over the network. The maximum of the two utilization
// measurements would be used as feedback.
// The parameter |frame_feedback_id| must match a |frame_feedback_id|
// previously sent out by the VideoCaptureDevice we are giving feedback about.
// It is used to indicate which particular frame the reported utilization
// corresponds to.
virtual void OnUtilizationReport(int frame_feedback_id, double utilization) {}
static constexpr double kNoUtilizationRecorded = -1.0;
class CAPTURE_EXPORT VideoCaptureDevice
: public VideoFrameConsumerFeedbackObserver {
// Interface defining the methods that clients of VideoCapture must have. It
// is actually two-in-one: clients may implement OnIncomingCapturedData() or
// ReserveOutputBuffer() + OnIncomingCapturedVideoFrame(), or all of them.
// All methods may be called as soon as AllocateAndStart() of the
// corresponding VideoCaptureDevice is invoked. The methods for buffer
// reservation and frame delivery may be called from arbitrary threads but
// are guaranteed to be called non-concurrently. The status reporting methods
// (OnStarted, OnLog, OnError) may be called concurrently.
class CAPTURE_EXPORT Client {
// Struct bundling several parameters being passed between a
// VideoCaptureDevice and its VideoCaptureDevice::Client.
struct CAPTURE_EXPORT Buffer {
// Destructor-only interface for encapsulating scoped access permission to
// a Buffer.
class CAPTURE_EXPORT ScopedAccessPermission {
virtual ~ScopedAccessPermission() {}
class CAPTURE_EXPORT HandleProvider {
virtual ~HandleProvider() {}
virtual mojo::ScopedSharedBufferHandle GetHandleForInterProcessTransit(
bool read_only) = 0;
virtual base::SharedMemoryHandle
GetNonOwnedSharedMemoryHandleForLegacyIPC() = 0;
virtual std::unique_ptr<VideoCaptureBufferHandle>
GetHandleForInProcessAccess() = 0;
Buffer(int buffer_id,
int frame_feedback_id,
std::unique_ptr<HandleProvider> handle_provider,
std::unique_ptr<ScopedAccessPermission> access_permission);
Buffer(Buffer&& other);
Buffer& operator=(Buffer&& other);
bool is_valid() const { return handle_provider != nullptr; }
int id;
int frame_feedback_id;
std::unique_ptr<HandleProvider> handle_provider;
std::unique_ptr<ScopedAccessPermission> access_permission;
virtual ~Client() {}
// Captured a new video frame, data for which is pointed to by |data|.
// The format of the frame is described by |frame_format|, and is assumed to
// be tightly packed. This method will try to reserve an output buffer and
// copy from |data| into the output buffer. If no output buffer is
// available, the frame will be silently dropped. |reference_time| is
// system clock time when we detect the capture happens, it is used for
// Audio/Video sync, not an exact presentation time for playout, because it
// could contain noise. |timestamp| measures the ideal time span between the
// first frame in the stream and the current frame; however, the time source
// is determined by the platform's device driver and is often not the system
// clock, or even has a drift with respect to system clock.
// |frame_feedback_id| is an identifier that allows clients to refer back to
// this particular frame when reporting consumer feedback via
// OnConsumerReportingUtilization(). This identifier is needed because
// frames are consumed asynchronously and multiple frames can be "in flight"
// at the same time.
virtual void OnIncomingCapturedData(const uint8_t* data,
int length,
const VideoCaptureFormat& frame_format,
int clockwise_rotation,
base::TimeTicks reference_time,
base::TimeDelta timestamp,
int frame_feedback_id = 0) = 0;
// Reserve an output buffer into which contents can be captured directly.
// The returned Buffer will always be allocated with a memory size suitable
// for holding a packed video frame with pixels of |format| format, of
// |dimensions| frame dimensions. It is permissible for |dimensions| to be
// zero; in which case the returned Buffer does not guarantee memory
// backing, but functions as a reservation for external input for the
// purposes of buffer throttling.
// The buffer stays reserved for use by the caller as long as it
// holds on to the contained |buffer_read_write_permission|.
virtual Buffer ReserveOutputBuffer(const gfx::Size& dimensions,
VideoPixelFormat format,
VideoPixelStorage storage,
int frame_feedback_id) = 0;
// Provides VCD::Client with a populated Buffer containing the content of
// the next video frame. The |buffer| must originate from an earlier call to
// ReserveOutputBuffer().
// See OnIncomingCapturedData for details of |reference_time| and
// |timestamp|.
virtual void OnIncomingCapturedBuffer(Buffer buffer,
const VideoCaptureFormat& format,
base::TimeTicks reference_time,
base::TimeDelta timestamp) = 0;
// Extended version of OnIncomingCapturedBuffer() allowing clients to
// pass a custom |visible_rect| and |additional_metadata|.
virtual void OnIncomingCapturedBufferExt(
Buffer buffer,
const VideoCaptureFormat& format,
base::TimeTicks reference_time,
base::TimeDelta timestamp,
gfx::Rect visible_rect,
const VideoFrameMetadata& additional_metadata) = 0;
// Attempts to reserve the same Buffer provided in the last call to one of
// the OnIncomingCapturedBufferXXX() methods. This will fail if the content
// of the Buffer has not been preserved, or if the |dimensions|, |format|,
// or |storage| disagree with how it was reserved via ReserveOutputBuffer().
// When this operation fails, nullptr will be returned.
virtual Buffer ResurrectLastOutputBuffer(const gfx::Size& dimensions,
VideoPixelFormat format,
VideoPixelStorage storage,
int new_frame_feedback_id) = 0;
// An error has occurred that cannot be handled and VideoCaptureDevice must
// be StopAndDeAllocate()-ed. |reason| is a text description of the error.
virtual void OnError(const base::Location& from_here,
const std::string& reason) = 0;
// VideoCaptureDevice requests the |message| to be logged.
virtual void OnLog(const std::string& message) {}
// Returns the current buffer pool utilization, in the range 0.0 (no buffers
// are in use by producers or consumers) to 1.0 (all buffers are in use).
virtual double GetBufferPoolUtilization() const = 0;
// VideoCaptureDevice reports it's successfully started.
virtual void OnStarted() = 0;
~VideoCaptureDevice() override;
// Prepares the video capturer for use. StopAndDeAllocate() must be called
// before the object is deleted.
virtual void AllocateAndStart(const VideoCaptureParams& params,
std::unique_ptr<Client> client) = 0;
// In cases where the video capturer self-pauses (e.g., a screen capturer
// where the screen's content has not changed in a while), consumers may call
// this to request a "refresh frame" be delivered to the Client. This is used
// in a number of circumstances, such as:
// 1. An additional consumer of video frames is starting up and requires a
// first frame (as opposed to not receiving a frame for an indeterminate
// amount of time).
// 2. A few repeats of the same frame would allow a lossy video encoder to
// improve the video quality of unchanging content.
// The default implementation is a no-op. VideoCaptureDevice implementations
// are not required to honor this request, especially if they do not
// self-pause and/or if honoring the request would cause them to exceed their
// configured maximum frame rate. Any VideoCaptureDevice that does self-pause,
// however, should provide an implementation of this method that makes
// reasonable attempts to honor these requests.
// Note: This should only be called after AllocateAndStart() and before
// StopAndDeAllocate(). Otherwise, its behavior is undefined.
virtual void RequestRefreshFrame() {}
// Optionally suspends frame delivery. The VideoCaptureDevice may or may not
// honor this request. Thus, the caller cannot assume frame delivery will
// actually stop. Even if frame delivery is suspended, this might not take
// effect immediately.
// The purpose of this is to quickly place the device into a state where it's
// resource utilization is minimized while there are no frame consumers; and
// then quickly resume once a frame consumer is present.
// Note: This should only be called after AllocateAndStart() and before
// StopAndDeAllocate(). Otherwise, its behavior is undefined.
virtual void MaybeSuspend() {}
// Resumes frame delivery, if it was suspended. If frame delivery was not
// suspended, this is a no-op, and frame delivery will continue.
// Note: This should only be called after AllocateAndStart() and before
// StopAndDeAllocate(). Otherwise, its behavior is undefined.
virtual void Resume() {}
// Deallocates the video capturer, possibly asynchronously.
// This call requires the device to do the following things, eventually: put
// hardware into a state where other applications could use it, free the
// memory associated with capture, and delete the |client| pointer passed into
// AllocateAndStart.
// If deallocation is done asynchronously, then the device implementation must
// ensure that a subsequent AllocateAndStart() operation targeting the same ID
// would be sequenced through the same task runner, so that deallocation
// happens first.
virtual void StopAndDeAllocate() = 0;
// Retrieve the photo capabilities and settings of the device (e.g. zoom
// levels etc). On success, invokes |callback|. On failure, drops callback
// without invoking it.
using GetPhotoStateCallback = base::OnceCallback<void(mojom::PhotoStatePtr)>;
virtual void GetPhotoState(GetPhotoStateCallback callback);
// On success, invokes |callback| with value |true|. On failure, drops
// callback without invoking it.
using SetPhotoOptionsCallback = base::OnceCallback<void(bool)>;
virtual void SetPhotoOptions(mojom::PhotoSettingsPtr settings,
SetPhotoOptionsCallback callback);
// Asynchronously takes a photo, possibly reconfiguring the capture objects
// and/or interrupting the capture flow. Runs |callback| on the thread
// where TakePhoto() is called, if the photo was successfully taken. On
// failure, drops callback without invoking it.
using TakePhotoCallback = base::OnceCallback<void(mojom::BlobPtr blob)>;
virtual void TakePhoto(TakePhotoCallback callback);
// Gets the power line frequency, either from the params if specified by the
// user or from the current system time zone.
PowerLineFrequency GetPowerLineFrequency(
const VideoCaptureParams& params) const;
// Gets the power line frequency from the current system time zone if this is
// defined, otherwise returns 0.
PowerLineFrequency GetPowerLineFrequencyForLocation() const;
} // namespace media