github.com/aamcrae/webcam@v0.0.0-20210915060337-934acc13bdc3/frame/yuyv422.go (about)

     1  // Copyright 2019 Google LLC
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     https://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package frame
    16  
    17  import (
    18  	"fmt"
    19  	"image"
    20  	"image/color"
    21  	"runtime"
    22  )
    23  
    24  type fYUYV422 struct {
    25  	model   color.Model
    26  	b       image.Rectangle
    27  	stride  int
    28  	size    int
    29  	frame   []byte
    30  	release func()
    31  }
    32  
    33  // Register a framer factory for this format.
    34  func init() {
    35  	RegisterFramer("YUYV", newFramerYUYV422)
    36  }
    37  
    38  func newFramerYUYV422(w, h, stride, size int) func([]byte, func()) (Frame, error) {
    39  	return func(b []byte, rel func()) (Frame, error) {
    40  		return frameYUYV422(size, stride, w, h, b, rel)
    41  	}
    42  }
    43  
    44  // Wrap a raw webcam frame in a Frame so that it can be used as an image.
    45  func frameYUYV422(size, stride, w, h int, b []byte, rel func()) (Frame, error) {
    46  	if len(b) != size {
    47  		if rel != nil {
    48  			defer rel()
    49  		}
    50  		return nil, fmt.Errorf("Wrong frame length (exp: %d, read %d)", size, len(b))
    51  	}
    52  	f := &fYUYV422{model: color.YCbCrModel, b: image.Rect(0, 0, w, h), stride: stride, frame: b, release: rel}
    53  	runtime.SetFinalizer(f, func(obj Frame) {
    54  		obj.Release()
    55  	})
    56  	return f, nil
    57  }
    58  
    59  func (f *fYUYV422) ColorModel() color.Model {
    60  	return f.model
    61  }
    62  
    63  func (f *fYUYV422) Bounds() image.Rectangle {
    64  	return f.b
    65  }
    66  
    67  func (f *fYUYV422) At(x, y int) color.Color {
    68  	index := f.stride*y + (x&^1)*2
    69  	if x&1 == 0 {
    70  		return color.YCbCr{f.frame[index], f.frame[index+1], f.frame[index+3]}
    71  	} else {
    72  		return color.YCbCr{f.frame[index+2], f.frame[index+1], f.frame[index+3]}
    73  	}
    74  }
    75  
    76  // Done with frame, release back to camera (if required).
    77  func (f *fYUYV422) Release() {
    78  	if f.release != nil {
    79  		f.release()
    80  		// Make sure it only gets called once.
    81  		f.release = nil
    82  	}
    83  }