inviwo::ffmpeg::Video Class Reference

Random access to the frames of a video file, decoded into Layers. More...

#include <inviwo/ffmpeg/video.h>

Inheritance diagram for inviwo::ffmpeg::Video:

Classes
struct	Info

Public Types
using	Seconds = std::chrono::duration<double>

Public Member Functions
std::ptrdiff_t	currentFrame () const
	Index of the most recently decoded frame, or -1 if nothing has been decoded yet.
Seconds	currentTime () const
	Presentation time of the most recently decoded frame.
const std::filesystem::path &	filename () const
std::ptrdiff_t	frameAt (Seconds time) const
	Index of the frame shown at time.
const Info &	info () const
Video &	operator= (const Video &)=delete
Video &	operator= (Video &&)=delete
std::shared_ptr< Layer >	readFrame (std::ptrdiff_t index, std::shared_ptr< Layer > reuse={})
	Decode the frame at index.
std::shared_ptr< Layer >	readNextFrame (std::shared_ptr< Layer > reuse={})
	Decode the frame following the most recently read one.
void	seekToFrame (std::ptrdiff_t index)
	Position the stream so that the next call to readNextFrame() returns frame index.
void	seekToTime (Seconds time)
	Position the stream so that the next call to readNextFrame() returns the frame at time.
int	streamIndex () const
Seconds	timeOf (std::ptrdiff_t index) const
	Presentation time of frame index.
	Video (const std::filesystem::path &filename, int streamIndex=-1)
	Open filename and prepare the video stream streamIndex for decoding.
	Video (const Video &)=delete
	Video (Video &&)=delete

Detailed Description

Random access to the frames of a video file, decoded into Layers.

Frames are converted to a Layer format matching the source as closely as possible, see Info::format. Color videos are decoded into RGBA, grayscale videos into a single channel, and sources with more than 8 bits per component are decoded into 16 bit Layers.

Seeking is done by seeking to the closest preceding keyframe and then decoding forward. Reading frames in order is therefore substantially faster than random access.

Constructor & Destructor Documentation

Video()

inviwo::ffmpeg::Video::Video ( const std::filesystem::path & filename, int streamIndex = -1 )

explicit

Open filename and prepare the video stream streamIndex for decoding.

Parameters

filename	video file to open
streamIndex	index of the video stream to decode, -1 selects the best one

Exceptions

Exception

if the file cannot be opened, holds no video stream, or if there is no decoder available for it

Member Function Documentation

readFrame()

std::shared_ptr< Layer > inviwo::ffmpeg::Video::readFrame	(	std::ptrdiff_t	index,
		std::shared_ptr< Layer >	reuse = {} )

Decode the frame at index.

Parameters

index	frame to read, negative values are counted from the end, that is -1 is the last frame
reuse	optional Layer to decode into. It is only used if it is non-null and matches the format, dimensions, and type of the decoded frames, otherwise it is ignored and a new Layer is allocated.

Returns

the decoded frame, or nullptr if the stream ended before reaching index

Exceptions

RangeException

if index is out of bounds

readNextFrame()

std::shared_ptr< Layer > inviwo::ffmpeg::Video::readNextFrame

(

std::shared_ptr< Layer >

reuse = {}

)

Decode the frame following the most recently read one.

Parameters

reuse

optional Layer to decode into,

See also

readFrame

Returns

the decoded frame, or nullptr at the end of the stream

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

• modules/ffmpeg/include/inviwo/ffmpeg/video.h