VideoEncoder Class Reference

Public Types
enum class	Codec {   HEVC_NVENC = 0 , HEVC_QSV , H264_NVENC , H264_QSV ,   AV1_NVENC , AV1_AOM , MPEG4 }
	List of algorithms used for video compression (Codec), IMPORTANT: the availability of these is dependent on the ffmpeg build unfortunately, unlike decoding, encoding using the generic CPU based codec for HEVC (and H264) cannot be added here due to licensing problems we should investigate hevc_v4l2m2m and libkvazaar for CPU based Encoder. More...
enum class	Preset { LowLatency = 0 , Balanced = 1 , HighQuality = 2 }
using	FrameCallback = std::function<void(std::unique_ptr<ByteBuffer>, bool)>

Public Member Functions
	VideoEncoder (FrameCallback frameCallback)
	Constructs the class with the given frame callback The frame callback is executed whenever a passed frame has been encoded by the background thread The callback is executed from the background thread, so proper synchronization must be ensured by the caller The parameters of the callback are a ByteBuffer containing the image data, and other used metadata.
bool	start (Codec encoderId, int fps, Preset preset=Preset::LowLatency)
	Starts the encoding thread with the given encoder parameters 'fps' is the expected frame rate of the video stream.
bool	stop ()
	Stops the encoder thread, if running.
void	restartEncoder ()
	Re-initializes the encoder state This can be used to reset the video stream, such that a client starting halfway through the stream can still decode it.
void	feedFrame (std::unique_ptr< ImFusion::MemImage > image)
	Pass a new image to the encoder thread, to be encoded into the video stream.
bool	lastImageProcessed () const
	return true if the algorithm had enough time to encode the previously stored image before the new one arrived

Static Public Member Functions
static std::vector< Codec >	availableCodecs ()
	Returns the available encoder provided by the ffmpeg library IMPORTANT: Not all codecs returned by this function are guaranteed work.
static std::string	codecName (Codec codec)

Member Enumeration Documentation

Codec

enum class Codec

strong

List of algorithms used for video compression (Codec), IMPORTANT: the availability of these is dependent on the ffmpeg build unfortunately, unlike decoding, encoding using the generic CPU based codec for HEVC (and H264) cannot be added here due to licensing problems we should investigate hevc_v4l2m2m and libkvazaar for CPU based Encoder.

Enumerator
HEVC_QSV	Hevc (h265) NVidia GPU based codec.
H264_NVENC	Hevc (h265) Intel GPU based codec.
H264_QSV	H264 NVidia GPU based codec.
AV1_NVENC	H264 Intel GPU based codec.
AV1_AOM	AV1 NVidia GPU based codec (Alliance for Open Media)
MPEG4	AV1 CPU codec (Alliance for Open Media) VP9 CPU codec (Moving Picture Experts Group)

Constructor & Destructor Documentation

VideoEncoder()

VideoEncoder

(

FrameCallback

frameCallback

)

Constructs the class with the given frame callback The frame callback is executed whenever a passed frame has been encoded by the background thread The callback is executed from the background thread, so proper synchronization must be ensured by the caller The parameters of the callback are a ByteBuffer containing the image data, and other used metadata.

Decoding applications typically expect to receive the first frame first, as it contains some information relevant to decoding.

Member Function Documentation

start()

bool start	(	Codec	encoderId,
		int	fps,
		Preset	preset = Preset::LowLatency )

Starts the encoding thread with the given encoder parameters 'fps' is the expected frame rate of the video stream.

This is only used for encoding in the metadata of the output video

stop()

bool stop

(

)

Stops the encoder thread, if running.

Blocks until the thread is joined.

feedFrame()

void feedFrame

(

std::unique_ptr< ImFusion::MemImage >

image

)

Pass a new image to the encoder thread, to be encoded into the video stream.

The function returns immediately, and the FrameCallback (passed in the constructor) will be called at a later point in time with the encoded data. Note that if a frame had not yet been processed by the background thread (either because they're supplied too fast or because the encoding is too slow), unhandled frames will be replaced by the new one

availableCodecs()

static std::vector< Codec > availableCodecs ( )

static

Returns the available encoder provided by the ffmpeg library IMPORTANT: Not all codecs returned by this function are guaranteed work.

For example, 'H264_NVENC' will only work if the GPU on the device supports it.

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The documentation for this class was generated from the following file:

• ImFusion/Stream/VideoEncoder.h