ffmpeg

Vidio

A simple Video I/O library written in Go. This library relies on FFmpeg, and FFProbe which must be downloaded before usage and added to the system path.

All frames are encoded and decoded in 8-bit RGB format.

Installation

go get github.com/AlexEidt/Vidio

Video

The Video struct stores data about a video file you give it. The code below shows an example of sequentially reading the frames of the given video.

Calling the Read() function will fill in the Video struct framebuffer with the next frame data as 8-bit RGB data, stored in a flattened byte array in row-major order where each pixel is represented by three consecutive bytes representing the R, G and B component of that pixel.

vidio.NewVideo() (*Video, error)

FileName() string
Width() int
Height() int
Depth() int
Bitrate() int
Frames() int
Duration() float64
FPS() float64
Codec() string
AudioCodec() string
PixFmt() string
FrameBuffer() []byte
SetFrameBuffer(buffer []byte)

Read() bool
Close()

video, err := vidio.NewVideo("input.mp4")

for video.Read() {
	// "frame" stores the video frame as a flattened RGB image in row-major order
	frame := video.FrameBuffer() // stored as: RGBRGBRGBRGB...
	// Video processing here...
}

If all frames have been read, video will be closed automatically. If not all frames are read, call video.Close() to close the video.

Camera

The Camera can read from any cameras on the device running Vidio. It takes in the stream index. On most machines the webcam device has index 0. Note that audio retrieval from the microphone is not yet supported.

vidio.NewCamera(stream int) (*Camera, error)

Name() string
Width() int
Height() int
Depth() int
FPS() float64
Codec() string
FrameBuffer() []byte
SetFrameBuffer(buffer []byte)

Read() bool
Close()

camera, err := vidio.NewCamera(0)

defer camera.Close()

// Stream the webcam
for camera.Read() {
	frame := camera.FrameBuffer()
	// Video processing here...
}

VideoWriter

The VideoWriter is used to write frames to a video file. The only required parameters are the output file name, the width and height of the frames being written, and an Options struct. This contains all the desired properties of the new video you want to create.

vidio.NewVideoWriter() (*VideoWriter, error)

FileName() string
Width() int
Height() int
Bitrate() int
Loop() int
Delay() int
Macro() int
FPS() float64
Quality() float64
Codec() string
AudioCodec() string

Write(frame []byte) error
Close()

type Options struct {
	Bitrate     int             // Bitrate
	Loop        int             // For GIFs only. -1=no loop, 0=loop forever, >0=loop n times
	Delay       int             // Delay for Final Frame of GIFs. Default -1 (Use same delay as previous frame)
	Macro       int             // macro size for determining how to resize frames for codecs. Default 16
	FPS         float64         // Frames per second. Default 25
	Quality     float64         // If bitrate not given, use quality instead. Must be between 0 and 1. 0:best, 1:worst
	Codec       string          // Codec for video. Default libx264
	Audio       string          // File path for audio for the video. If no audio, audio=""
	AudioCodec  string          // Codec for audio. Default aac
}

w, h, c := 1920, 1080, 3
options := vidio.Options{} // Will fill in defaults if empty

writer, err := vidio.NewVideoWriter("output.mp4", w, h, &options)

defer writer.Close()

frame := make([]byte, w*h*c) // Create Frame as RGB Image and modify
writer.Write(frame) // Write Frame to video

The SetFrameBuffer(buffer []byte) method

For the SetFrameBuffer() method, the buffer parameter must have a length of at least video.Width() * video.Height() * video.Depth() bytes to store the incoming video frame. The length of the buffer is not checked. It may be useful to have multiple buffers to keep track of previous video frames without having to copy data around.

Images

Vidio provides some convenience functions for reading and writing to images using an array of bytes. Currently, only png and jpeg formats are supported. When reading images, an optional buffer can be passed in to avoid array reallocation.

Read(filename string, buffer ...[]byte) (int, int, []byte, error)
Write(filename string, width, height int, buffer []byte) error

w, h, img, err := vidio.Read("input.png")

err := vidio.Write("output.jpg", w, h, img)

Examples

Copy input.mp4 to output.mp4. Copy the audio from input.mp4 to output.mp4 as well.

video, err := vidio.NewVideo("input.mp4")

options := vidio.Options{
	FPS: video.FPS(),
	Bitrate: video.Bitrate(),
	Audio: "input.mp4",
}

writer, err := vidio.NewVideoWriter("output.mp4", video.Width(), video.Height(), &options)

defer writer.Close()

for video.Read() {
    writer.Write(video.FrameBuffer())
}

Grayscale 1000 frames of webcam stream and store in output.mp4.

webcam, err := vidio.NewCamera(0)

defer webcam.Close()

options := vidio.Options{FPS: webcam.FPS()}

writer, err := vidio.NewVideoWriter("output.mp4", webcam.Width(), webcam.Height(), &options)

defer writer.Close()

count := 0
for webcam.Read() {
	frame := webcam.FrameBuffer()
	for i := 0; i < len(frame); i += 3 {
		r, g, b := frame[i+0], frame[i+1], frame[i+2]
		gray := uint8((3*int(r) + 4*int(g) + int(b)) / 8)
		frame[i] = gray
		frame[i+1] = gray
		frame[i+2] = gray
	}

	writer.Write(frame)

	count++
	if count > 1000 {
		break
	}
}

Create a gif from a series of png files enumerated from 1 to 10 that loops continuously with a final frame delay of 1000 centiseconds.

w, h, img, err := vidio.Read("1.png") // Get frame dimensions from first image

options := vidio.Options{FPS: 1, Loop: 0, Delay: 1000}

gif, err := vidio.NewVideoWriter("output.gif", w, h, &options)

defer gif.Close()

for i := 1; i <= 10; i++ {
	w, h, img, err := vidio.Read(strconv.Itoa(i)+".png")
	gif.Write(img)
}

Acknowledgements

• Special thanks to Zulko and his blog post about using FFmpeg to process video.
• The ImageIO-FFMPEG project on GitHub.