150 lines
2.8 KiB
Go
150 lines
2.8 KiB
Go
package y4m
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import (
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"bytes"
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"image"
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"github.com/AlexxIT/go2rtc/pkg/core"
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)
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const FourCC = "YUV4"
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const frameHdr = "FRAME\n"
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func ParseHeader(b []byte) (fmtp string) {
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for b != nil {
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// YUV4MPEG2 W1280 H720 F24:1 Ip A1:1 C420mpeg2 XYSCSS=420MPEG2
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// https://manned.org/yuv4mpeg.5
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// https://github.com/FFmpeg/FFmpeg/blob/master/libavformat/yuv4mpegenc.c
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key := b[0]
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var value string
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if i := bytes.IndexByte(b, ' '); i > 0 {
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value = string(b[1:i])
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b = b[i+1:]
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} else {
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value = string(b[1:])
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b = nil
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}
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switch key {
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case 'W':
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fmtp = "width=" + value
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case 'H':
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fmtp += ";height=" + value
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case 'C':
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fmtp += ";colorspace=" + value
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}
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}
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return
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}
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func GetSize(fmtp string) int {
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w := core.Atoi(core.Between(fmtp, "width=", ";"))
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h := core.Atoi(core.Between(fmtp, "height=", ";"))
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switch core.Between(fmtp, "colorspace=", ";") {
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case "mono":
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return w * h
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case "420mpeg2", "420jpeg":
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return w * h * 3 / 2
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case "422":
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return w * h * 2
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case "444":
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return w * h * 3
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}
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return 0
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}
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func NewImage(fmtp string) func(frame []byte) image.Image {
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w := core.Atoi(core.Between(fmtp, "width=", ";"))
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h := core.Atoi(core.Between(fmtp, "height=", ";"))
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rect := image.Rect(0, 0, w, h)
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switch core.Between(fmtp, "colorspace=", ";") {
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case "mono":
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return func(frame []byte) image.Image {
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return &image.Gray{
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Pix: frame,
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Stride: w,
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Rect: rect,
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}
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}
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case "420mpeg2", "420jpeg":
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i1 := w * h
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i2 := i1 + i1/4
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i3 := i2 + i1/4
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return func(frame []byte) image.Image {
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return &image.YCbCr{
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Y: frame[:i1],
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Cb: frame[i1:i2],
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Cr: frame[i2:i3],
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YStride: w,
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CStride: w / 2,
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SubsampleRatio: image.YCbCrSubsampleRatio420,
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Rect: rect,
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}
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}
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case "422":
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i1 := w * h
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i2 := i1 + i1/2
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i3 := i2 + i1/2
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return func(frame []byte) image.Image {
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return &image.YCbCr{
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Y: frame[:i1],
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Cb: frame[i1:i2],
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Cr: frame[i2:i3],
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YStride: w,
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CStride: w / 2,
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SubsampleRatio: image.YCbCrSubsampleRatio422,
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Rect: rect,
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}
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}
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case "444":
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i1 := w * h
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i2 := i1 + i1
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i3 := i2 + i1
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return func(frame []byte) image.Image {
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return &image.YCbCr{
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Y: frame[:i1],
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Cb: frame[i1:i2],
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Cr: frame[i2:i3],
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YStride: w,
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CStride: w,
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SubsampleRatio: image.YCbCrSubsampleRatio444,
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Rect: rect,
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}
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}
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}
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return nil
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}
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// HasSameColor checks if all pixels has same color
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func HasSameColor(img image.Image) bool {
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var pix []byte
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switch img := img.(type) {
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case *image.Gray:
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pix = img.Pix
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case *image.YCbCr:
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pix = img.Y
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}
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if len(pix) == 0 {
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return false
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}
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i0 := pix[0]
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for _, i := range pix {
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if i != i0 {
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return false
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}
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}
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return true
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}
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