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Add CGO version of I420 convert

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This commit is contained in:
Atsushi Watanabe
2020-02-17 19:14:31 +09:00
parent 0c6c27186c
commit d3a0713c39
4 changed files with 166 additions and 39 deletions
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98
pkg/io/video/convert.go
View File

@@ -6,6 +6,10 @@ import (
"image/color"
)
var (
hasCGOConvert = false
)
// imageToYCbCr converts src to *image.YCbCr and store it to dst
// Note: conversion can be lossy
func imageToYCbCr(dst *image.YCbCr, src image.Image) {
@@ -70,8 +74,61 @@ func imageToYCbCr(dst *image.YCbCr, src image.Image) {
}
}
func i444ToI420(img *image.YCbCr) {
h := img.Rect.Dy()
addrSrc0 := 0
addrSrc1 := img.CStride
addrDst := 0
for i := 0; i < h/2; i++ {
for j := 0; j < img.CStride/2; j++ {
cb := uint16(img.Cb[addrSrc0]) + uint16(img.Cb[addrSrc1]) +
uint16(img.Cb[addrSrc0+1]) + uint16(img.Cb[addrSrc1+1])
cr := uint16(img.Cr[addrSrc0]) + uint16(img.Cr[addrSrc1]) +
uint16(img.Cr[addrSrc0+1]) + uint16(img.Cr[addrSrc1+1])
img.Cb[addrDst] = uint8(cb / 4)
img.Cr[addrDst] = uint8(cr / 4)
addrSrc0 += 2
addrSrc1 += 2
addrDst++
}
addrSrc0 += img.CStride
addrSrc1 += img.CStride
}
img.CStride = img.CStride / 2
cLen := img.CStride * (h / 2)
img.Cb = img.Cb[:cLen]
img.Cr = img.Cr[:cLen]
}
func i422ToI420(img *image.YCbCr) {
h := img.Rect.Dy()
addrSrc := 0
addrDst := 0
for i := 0; i < h/2; i++ {
for j := 0; j < img.CStride; j++ {
cb := uint16(img.Cb[addrSrc]) + uint16(img.Cb[addrSrc+img.CStride])
cr := uint16(img.Cr[addrSrc]) + uint16(img.Cr[addrSrc+img.CStride])
img.Cb[addrDst] = uint8(cb / 2)
img.Cr[addrDst] = uint8(cr / 2)
addrDst++
addrSrc++
}
addrSrc += img.CStride
}
cLen := img.CStride * (h / 2)
img.Cb = img.Cb[:cLen]
img.Cr = img.Cr[:cLen]
}
// ToI420 converts r to a new reader that will output images in I420 format
func ToI420(r Reader) Reader {
f444to420 := i444ToI420
f422to420 := i422ToI420
if hasCGOConvert {
f444to420 = i444ToI420CGO
f422to420 = i422ToI420CGO
}
var yuvImg image.YCbCr
return ReaderFunc(func() (image.Image, error) {
img, err := r.Read()
@@ -80,50 +137,13 @@ func ToI420(r Reader) Reader {
}
imageToYCbCr(&yuvImg, img)
h := yuvImg.Rect.Dy()
// Covert pixel format to I420
switch yuvImg.SubsampleRatio {
case image.YCbCrSubsampleRatio444:
addrSrc0 := 0
addrSrc1 := yuvImg.CStride
addrDst := 0
for i := 0; i < h/2; i++ {
for j := 0; j < yuvImg.CStride/2; j++ {
cb := uint16(yuvImg.Cb[addrSrc0]) + uint16(yuvImg.Cb[addrSrc1]) +
uint16(yuvImg.Cb[addrSrc0+1]) + uint16(yuvImg.Cb[addrSrc1+1])
cr := uint16(yuvImg.Cr[addrSrc0]) + uint16(yuvImg.Cr[addrSrc1]) +
uint16(yuvImg.Cr[addrSrc0+1]) + uint16(yuvImg.Cr[addrSrc1+1])
yuvImg.Cb[addrDst] = uint8(cb / 4)
yuvImg.Cr[addrDst] = uint8(cr / 4)
addrSrc0 += 2
addrSrc1 += 2
addrDst++
}
addrSrc0 += yuvImg.CStride
addrSrc1 += yuvImg.CStride
}
yuvImg.CStride = yuvImg.CStride / 2
cLen := yuvImg.CStride * (h / 2)
yuvImg.Cb = yuvImg.Cb[:cLen]
yuvImg.Cr = yuvImg.Cr[:cLen]
f444to420(&yuvImg)
case image.YCbCrSubsampleRatio422:
addrSrc := 0
addrDst := 0
for i := 0; i < h/2; i++ {
for j := 0; j < yuvImg.CStride; j++ {
cb := uint16(yuvImg.Cb[addrSrc]) + uint16(yuvImg.Cb[addrSrc+yuvImg.CStride])
cr := uint16(yuvImg.Cr[addrSrc]) + uint16(yuvImg.Cr[addrSrc+yuvImg.CStride])
yuvImg.Cb[addrDst] = uint8(cb / 2)
yuvImg.Cr[addrDst] = uint8(cr / 2)
addrDst++
addrSrc++
}
addrSrc += yuvImg.CStride
}
cLen := yuvImg.CStride * (h / 2)
yuvImg.Cb = yuvImg.Cb[:cLen]
yuvImg.Cr = yuvImg.Cr[:cLen]
f422to420(&yuvImg)
case image.YCbCrSubsampleRatio420:
default:
return nil, fmt.Errorf("unsupported pixel format: %s", yuvImg.SubsampleRatio)

56
pkg/io/video/convert_cgo.c Normal file
View File

@@ -0,0 +1,56 @@
#include <stdint.h>
#include "_cgo_export.h"
void i444ToI420CGO(
unsigned char* cb,
unsigned char* cr,
const int stride, const int h)
{
int isrc0 = 0;
int isrc1 = stride;
int idst = 0;
for (int y = 0; y < h / 2; y++)
{
for (int x = 0; x < stride / 2; x++)
{
const uint8_t cb2 =
((uint16_t)cb[isrc0] + (uint16_t)cb[isrc1] +
(uint16_t)cb[isrc0 + 1] + (uint16_t)cb[isrc1 + 1]) /
4;
const uint8_t cr2 =
((uint16_t)cr[isrc0] + (uint16_t)cr[isrc1] +
(uint16_t)cr[isrc0 + 1] + (uint16_t)cr[isrc1 + 1]) /
4;
cb[idst] = cb2;
cr[idst] = cr2;
isrc0 += 2;
isrc1 += 2;
idst++;
}
isrc0 += stride;
isrc1 += stride;
}
}
void i422ToI420CGO(
unsigned char* cb,
unsigned char* cr,
const int stride, const int h)
{
int isrc = 0;
int idst = 0;
for (int y = 0; y < h / 2; y++)
{
for (int x = 0; x < stride; x++)
{
const uint8_t cb2 = ((uint16_t)cb[isrc] + (uint16_t)cb[isrc + stride]) / 2;
const uint8_t cr2 = ((uint16_t)cr[isrc] + (uint16_t)cr[isrc + stride]) / 2;
cb[idst] = cb2;
cr[idst] = cr2;
isrc++;
idst++;
}
isrc += stride;
}
}

42
pkg/io/video/convert_cgo.go Normal file
View File

@@ -0,0 +1,42 @@
// +build cgo
package video
import (
"image"
)
// void i444ToI420CGO(
// unsigned char* cb, unsigned char* cr,
// const int stride, const int h);
// void i422ToI420CGO(
// unsigned char* cb, unsigned char* cr,
// const int stride, const int h);
import "C"
func init() {
hasCGOConvert = true
}
func i444ToI420CGO(img *image.YCbCr) {
h := img.Rect.Dy()
C.i444ToI420CGO(
(*C.uchar)(&img.Cb[0]), (*C.uchar)(&img.Cr[0]),
C.int(img.CStride), C.int(h),
)
img.CStride = img.CStride / 2
cLen := img.CStride * (h / 2)
img.Cb = img.Cb[:cLen]
img.Cr = img.Cr[:cLen]
}
func i422ToI420CGO(img *image.YCbCr) {
h := img.Rect.Dy()
C.i422ToI420CGO(
(*C.uchar)(&img.Cb[0]), (*C.uchar)(&img.Cr[0]),
C.int(img.CStride), C.int(h),
)
cLen := img.CStride * (h / 2)
img.Cb = img.Cb[:cLen]
img.Cr = img.Cr[:cLen]
}

9
pkg/io/video/convert_test.go
View File

@@ -152,3 +152,12 @@ func BenchmarkToI420(b *testing.B) {
})
}
}
func BenchmarkToI420CGO(b *testing.B) {
if !hasCGOConvert {
b.SkipNow()
}
hasCGOConvert = false
b.Run("NoCGO", BenchmarkToI420)
hasCGOConvert = true
}