104 lines
3.5 KiB
Objective-C
104 lines
3.5 KiB
Objective-C
//
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// SCSingleFrameStreamCapturer.m
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// Snapchat
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//
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// Created by Benjamin Hollis on 5/3/16.
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// Copyright © 2016 Snapchat, Inc. All rights reserved.
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//
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#import "SCSingleFrameStreamCapturer.h"
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#import "SCManagedCapturer.h"
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@implementation SCSingleFrameStreamCapturer {
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sc_managed_capturer_capture_video_frame_completion_handler_t _callback;
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}
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- (instancetype)initWithCompletion:(sc_managed_capturer_capture_video_frame_completion_handler_t)completionHandler
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{
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self = [super init];
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if (self) {
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_callback = completionHandler;
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}
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return self;
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}
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#pragma mark - SCManagedVideoDataSourceListener
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- (void)managedVideoDataSource:(id<SCManagedVideoDataSource>)managedVideoDataSource
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didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
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devicePosition:(SCManagedCaptureDevicePosition)devicePosition
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{
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if (_callback) {
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UIImage *image = [self imageFromSampleBuffer:sampleBuffer];
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_callback(image);
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}
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_callback = nil;
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}
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/**
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* Decode a CMSampleBufferRef to our native camera format (kCVPixelFormatType_420YpCbCr8BiPlanarFullRange,
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* as set in SCManagedVideoStreamer) to a UIImage.
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*
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* Code from http://stackoverflow.com/a/31553521/11284
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*/
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#define clamp(a) (a > 255 ? 255 : (a < 0 ? 0 : a))
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// TODO: Use the transform code from SCImageProcessIdentityYUVCommand
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- (UIImage *)imageFromSampleBuffer:(CMSampleBufferRef)sampleBuffer
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{
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CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
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CVPixelBufferLockBaseAddress(imageBuffer, 0);
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size_t width = CVPixelBufferGetWidth(imageBuffer);
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size_t height = CVPixelBufferGetHeight(imageBuffer);
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uint8_t *yBuffer = CVPixelBufferGetBaseAddressOfPlane(imageBuffer, 0);
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size_t yPitch = CVPixelBufferGetBytesPerRowOfPlane(imageBuffer, 0);
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uint8_t *cbCrBuffer = CVPixelBufferGetBaseAddressOfPlane(imageBuffer, 1);
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size_t cbCrPitch = CVPixelBufferGetBytesPerRowOfPlane(imageBuffer, 1);
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int bytesPerPixel = 4;
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uint8_t *rgbBuffer = malloc(width * height * bytesPerPixel);
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for (int y = 0; y < height; y++) {
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uint8_t *rgbBufferLine = &rgbBuffer[y * width * bytesPerPixel];
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uint8_t *yBufferLine = &yBuffer[y * yPitch];
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uint8_t *cbCrBufferLine = &cbCrBuffer[(y >> 1) * cbCrPitch];
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for (int x = 0; x < width; x++) {
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int16_t y = yBufferLine[x];
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int16_t cb = cbCrBufferLine[x & ~1] - 128;
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int16_t cr = cbCrBufferLine[x | 1] - 128;
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uint8_t *rgbOutput = &rgbBufferLine[x * bytesPerPixel];
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int16_t r = (int16_t)roundf(y + cr * 1.4);
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int16_t g = (int16_t)roundf(y + cb * -0.343 + cr * -0.711);
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int16_t b = (int16_t)roundf(y + cb * 1.765);
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rgbOutput[0] = 0xff;
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rgbOutput[1] = clamp(b);
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rgbOutput[2] = clamp(g);
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rgbOutput[3] = clamp(r);
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}
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}
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CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
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CGContextRef context = CGBitmapContextCreate(rgbBuffer, width, height, 8, width * bytesPerPixel, colorSpace,
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kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast);
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CGImageRef quartzImage = CGBitmapContextCreateImage(context);
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// TODO: Hardcoding UIImageOrientationRight seems cheesy
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UIImage *image = [UIImage imageWithCGImage:quartzImage scale:1.0 orientation:UIImageOrientationRight];
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CGContextRelease(context);
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CGColorSpaceRelease(colorSpace);
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CGImageRelease(quartzImage);
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free(rgbBuffer);
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CVPixelBufferUnlockBaseAddress(imageBuffer, 0);
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return image;
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}
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@end
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