libyuv下载地址
链接: https://pan.baidu.com/s/1DTInjVivZHQW0PnzJYQK5g 提取码: cy4b
我也是在网上查找了好多东西,自己试出来可以正常转化将nv12数据分辨率的方法,有的地方也并不能完全解释,但确实可行,仅供参考吧,也是自己记录下,因为这个过程真的好辛苦,从找到nv12转化分辨率到将yuv转化成CVPixelBufferRef,再到CMSampleBufferRef.
过程:得到CMSampleBufferRef(此处得到的是420f,也是nv12,也是kCVPixelFormatType_420YpCbCr8BiPlanarFullRange),解析得到nv12格式yuv数据.利用libyuv ,先将nv12转化成I420,通过I420转化分辨率,再将I420转化成nv12,用到的libyuv的方法有三个:NV12ToI420,I420Scale,I420ToNV12.
首先我运用的场景是通过系统的录屏方法获取到的CMSampleBufferRef,得到的视频流分辨率是1080*1920,但是我需要的是720 *1280.
[[RPScreenRecorder sharedRecorder] startCaptureWithHandler:^(CMSampleBufferRef _Nonnull sampleBuffer, RPSampleBufferType bufferType, NSError * _Nullable error) {
if (bufferType == RPSampleBufferTypeVideo && sampleBuffer != nil) {
CVPixelBufferRef pixel =[self convertVideoSmapleBufferToYuvData:sampleBuffer];
CMSampleBufferRef sample = [self pixelBufferToSampleBuffer:pixel];
[self setwangyiBuffer:sample];
}
} completionHandler:^(NSError * _Nullable error) {}];
其中 [[RPScreenRecorder sharedRecorder] startCaptureWithHandler:^(CMSampleBufferRef _Nonnull sampleBuffer, RPSampleBufferType bufferType, NSError * _Nullable error) 是系统的录屏方法,可以直接得到录屏数据的视频流,CVPixelBufferRef pixel =[self convertVideoSmapleBufferToYuvData:sampleBuffer];
是我自己转化调用的方法其中shareSWidth = 720;
shareSHeight = 1280;
//转化
-(CVPixelBufferRef)convertVideoSmapleBufferToYuvData:(CMSampleBufferRef) videoSample{
// 1.
//CVPixelBufferRef是CVImageBufferRef的别名，两者操作几乎一致。
//获取CMSampleBuffer的图像地址
CVImageBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(videoSample);
//表示开始操作数据
CVPixelBufferLockBaseAddress(pixelBuffer, 0);
//图像宽度（像素）
size_t pixelWidth = CVPixelBufferGetWidth(pixelBuffer);
//图像高度（像素）
size_t pixelHeight = CVPixelBufferGetHeight(pixelBuffer);
//获取CVImageBufferRef中的y数据
uint8_t *y_frame = (unsigned char *)CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 0);
//获取CMVImageBufferRef中的uv数据
uint8_t *uv_frame =(unsigned char *) CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 1);
//y stride
size_t plane1_stride = CVPixelBufferGetBytesPerRowOfPlane (pixelBuffer, 0);
//uv stride
size_t plane2_stride = CVPixelBufferGetBytesPerRowOfPlane (pixelBuffer, 1);
//y_size
size_t plane1_size = plane1_stride * CVPixelBufferGetHeightOfPlane(pixelBuffer, 0);
//uv_size
size_t plane2_size = CVPixelBufferGetBytesPerRowOfPlane (pixelBuffer, 1) * CVPixelBufferGetHeightOfPlane(pixelBuffer, 1);
//yuv_size(内存空间)
size_t frame_size = plane1_size + plane2_size;
//开辟frame_size大小的内存空间用于存放转换好的i420数据
uint8* buffer = (unsigned char *)malloc(frame_size);
//buffer为这段内存的首地址,plane1_size代表这一帧中y数据的长度
uint8* dst_u = buffer + plane1_size;
//dst_u为u数据的首地,plane1_size/4为u数据的长度
uint8* dst_v = dst_u + plane1_size/4;
// Let libyuv convert
libyuv::NV12ToI420(y_frame,plane1_stride,
uv_frame, plane2_stride,
buffer, plane1_stride,
dst_u,plane2_stride/2,
dst_v, plane2_stride/2,
pixelWidth, pixelHeight);
// 2
//scale-size
int scale_yuvBufSize = shareSWidth * shareSHeight * 3 / 2;
//uint8_t* scale_yuvBuf= new uint8_t[scale_yuvBufSize];
uint8* scale_yuvBuf = (unsigned char *)malloc(scale_yuvBufSize);
//scale-stride
const int32 scale_uv_stride = (shareSWidth + 1) / 2;
//scale-length
const int scale_y_length = shareSWidth * shareSHeight;
int scale_uv_length = scale_uv_stride * ((shareSWidth+1) / 2);
unsigned char *scale_Y_data_Dst = scale_yuvBuf;
unsigned char *scale_U_data_Dst = scale_yuvBuf + scale_y_length;
unsigned char *scale_V_data_Dst = scale_U_data_Dst + scale_y_length/4;
libyuv::I420Scale(buffer, plane1_stride, dst_u, plane2_stride/2, dst_v, plane2_stride/2, pixelWidth, pixelHeight, scale_Y_data_Dst, shareSWidth,
scale_U_data_Dst, scale_uv_stride,
scale_V_data_Dst, scale_uv_stride,
shareSWidth, shareSHeight,
libyuv::kFilterNone);
// 3.
uint8 *dst_y = (uint8 *)malloc((shareSWidth * shareSHeight * 3) >> 1);
int dst_Stride_Y = shareSWidth;
uint8 *dst_uv = dst_y + shareSWidth*shareSHeight;
int dst_Stride_uv = shareSWidth/2;
libyuv::I420ToNV12(scale_Y_data_Dst, shareSWidth,
scale_U_data_Dst, scale_uv_stride,
scale_V_data_Dst, scale_uv_stride,dst_y, dst_Stride_Y, dst_uv, dst_Stride_Y,shareSWidth, shareSHeight);
CVPixelBufferUnlockBaseAddress(pixelBuffer, 0);
free(buffer);
free(scale_yuvBuf);
//转化
NSDictionary *pixelAttributes = @{(id)kCVPixelBufferIOSurfacePropertiesKey : @{}};
CVPixelBufferRef pixelBuffer1 = NULL;
CVReturn result = CVPixelBufferCreate(kCFAllocatorDefault,
shareSWidth,shareSHeight,kCVPixelFormatType_420YpCbCr8BiPlanarFullRange,
(__bridge CFDictionaryRef)pixelAttributes,&pixelBuffer1);
CVPixelBufferLockBaseAddress(pixelBuffer1, 0);
uint8_t *yDestPlane = (uint8*)CVPixelBufferGetBaseAddressOfPlane(pixelBuffer1, 0);
memcpy(yDestPlane, dst_y, shareSWidth * shareSHeight);
uint8_t *uvDestPlane = (uint8*)CVPixelBufferGetBaseAddressOfPlane(pixelBuffer1, 1);
memcpy(uvDestPlane, dst_uv, shareSWidth * shareSHeight/2);
if (result != kCVReturnSuccess) {
NSLog(@"Unable to create cvpixelbuffer %d", result);
}
CVPixelBufferUnlockBaseAddress(pixelBuffer1, 0);
free(dst_y);
// CVPixelBufferRelease(pixelBuffer1);
return pixelBuffer1;
}
时间戳
-(CMSampleBufferRef)pixelBufferToSampleBuffer:(CVPixelBufferRef)pixelBuffer
{
CMSampleBufferRef sampleBuffer;
CMTime frameTime = CMTimeMakeWithSeconds([[NSDate date] timeIntervalSince1970], 1000000000);
CMSampleTimingInfo timing = {frameTime, frameTime, kCMTimeInvalid};
CMVideoFormatDescriptionRef videoInfo = NULL;
CMVideoFormatDescriptionCreateForImageBuffer(NULL, pixelBuffer, &videoInfo);
OSStatus status = CMSampleBufferCreateForImageBuffer(kCFAllocatorDefault, pixelBuffer, true, NULL, NULL, videoInfo, &timing, &sampleBuffer);
if (status != noErr) {
NSLog(@"Failed to create sample buffer with error %zd.", status);
}
CVPixelBufferRelease(pixelBuffer);
if(videoInfo)
CFRelease(videoInfo);
return sampleBuffer;
}
参考链接
https://blog.csdn.net/sinat_36684217/article/details/75117920
https://www.jianshu.com/p/050234c5fff2
https://www.jianshu.com/p/68e05ad85490
https://www.jianshu.com/p/dac9857b34d0
