- 创建录制VideoCapture
- 接口
#import
@interface VideoCapture : NSObject
- (void)startCapture:(UIView *)preview;
- (void)stopCapture;
@end
- 实现
#import "VideoCapture.h"
#import "VideoEncoder.h"
#import
@interface VideoCapture ()
/** 编码对象 */
@property (nonatomic, strong) VideoEncoder *encoder;
/** 捕捉会话*/
@property (nonatomic, weak) AVCaptureSession *captureSession;
/** 预览图层 */
@property (nonatomic, weak) AVCaptureVideoPreviewLayer *previewLayer;
/** 捕捉画面执行的线程队列 */
@property (nonatomic, strong) dispatch_queue_t captureQueue;
@end
@implementation VideoCapture
- (void)startCapture:(UIView *)preview
{
// 0.初始化编码对象
self.encoder = [[VideoEncoder alloc] init];
// 1.创建捕捉会话
AVCaptureSession *session = [[AVCaptureSession alloc] init];
session.sessionPreset = AVCaptureSessionPreset1280x720;
self.captureSession = session;
// 2.设置输入设备
AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
NSError *error = nil;
AVCaptureDeviceInput *input = [[AVCaptureDeviceInput alloc] initWithDevice:device error:&error];
[session addInput:input];
// 3.添加输出设备
AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init];
self.captureQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
[output setSampleBufferDelegate:self queue:self.captureQueue];
[session addOutput:output];
// 设置录制视频的方向
AVCaptureConnection *connection = [output connectionWithMediaType:AVMediaTypeVideo];
[connection setVideoOrientation:AVCaptureVideoOrientationPortrait];
// 4.添加预览图层
AVCaptureVideoPreviewLayer *previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
previewLayer.frame = preview.bounds;
[preview.layer insertSublayer:previewLayer atIndex:0];
self.previewLayer = previewLayer;
// 5.开始捕捉
[self.captureSession startRunning];
}
- (void)stopCapture {
[self.captureSession stopRunning];
[self.previewLayer removeFromSuperlayer];
[self.encoder endEncode];
}
#pragma mark - 获取到数据
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
[self.encoder encodeSampleBuffer:sampleBuffer];
}
创建编码类
VideoEncoder.h
#import
#import
@interface VideoEncoder : NSObject
- (void)encodeSampleBuffer:(CMSampleBufferRef)sampleBuffer;
- (void)endEncode;
@end
- VideoEncoder.m
- 开始编码
#import "VideoEncoder.h"
@interface VideoEncoder()
/** 记录当前的帧数 */
@property (nonatomic, assign) NSInteger frameID;
/** 编码会话 */
@property (nonatomic, assign) VTCompressionSessionRef compressionSession;
/** 文件写入对象 */
@property (nonatomic, strong) NSFileHandle *fileHandle;
@end
@implementation VideoEncoder
- (instancetype)init {
if (self = [super init]) {
// 1.初始化写入文件的对象(NSFileHandle用于写入二进制文件)
[self setupFileHandle];
// 2.初始化压缩编码的会话
[self setupVideoSession];
}
return self;
}
- (void)setupFileHandle {
// 1.获取沙盒路径
NSString *file = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"abc.h264"];
// 2.如果原来有文件,则删除
[[NSFileManager defaultManager] removeItemAtPath:file error:nil];
[[NSFileManager defaultManager] createFileAtPath:file contents:nil attributes:nil];
// 3.创建对象
self.fileHandle = [NSFileHandle fileHandleForWritingAtPath:file];
}
- (void)setupVideoSession {
// 1.用于记录当前是第几帧数据(画面帧数非常多)
self.frameID = 0;
// 2.录制视频的宽度&高度
int width = [UIScreen mainScreen].bounds.size.width;
int height = [UIScreen mainScreen].bounds.size.height;
// 1 NULL 2 W 3 H
// 3.创建CompressionSession对象,该对象用于对画面进行编码
// kCMVideoCodecType_H264 : 表示使用h.264进行编码
// didCompressH264 : 当一次编码结束会在该函数进行回调,可以在该函数中将数据,写入文件中
VTCompressionSessionCreate(NULL, width, height, kCMVideoCodecType_H264, NULL, NULL, NULL, didCompressH264, (__bridge void *)(self), &_compressionSession);
// 4.设置实时编码输出（直播必然是实时输出,否则会有延迟）//不做直播不设置也可以
VTSessionSetProperty(self.compressionSession, kVTCompressionPropertyKey_RealTime, kCFBooleanTrue);
// 5.设置期望帧率(每秒多少帧,如果帧率过低,会造成画面卡顿)
int fps = 30;
CFNumberRef fpsRef = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &fps);
VTSessionSetProperty(self.compressionSession, kVTCompressionPropertyKey_ExpectedFrameRate, fpsRef);
// 6.设置码率(码率: 编码效率, 码率越高,则画面越清晰, 如果码率较低会引起马赛克 --> 码率高有利于还原原始画面,但是也不利于传输) 单位时间内保存的数据流 一般情况下采集画面的宽度*高度
int bitRate = 800*1024;
CFNumberRef bitRateRef = CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &bitRate);
VTSessionSetProperty(self.compressionSession, kVTCompressionPropertyKey_AverageBitRate, bitRateRef);
NSArray *limit = @[@(bitRate * 1.5/8), @(1)];
VTSessionSetProperty(self.compressionSession, kVTCompressionPropertyKey_DataRateLimits, (__bridge CFArrayRef)limit);
// 7.设置关键帧（GOPsize)间隔
int frameInterval = 30;
CFNumberRef frameIntervalRef = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &frameInterval);
VTSessionSetProperty(self.compressionSession, kVTCompressionPropertyKey_MaxKeyFrameInterval, frameIntervalRef);
// 8.基本设置结束, 准备进行编码
VTCompressionSessionPrepareToEncodeFrames(self.compressionSession);
}
// 编码完成回调
void didCompressH264(void *outputCallbackRefCon, void *sourceFrameRefCon, OSStatus status, VTEncodeInfoFlags infoFlags, CMSampleBufferRef sampleBuffer) {
// 1.判断状态是否等于没有错误
if (status != noErr) {
return;
}
// 2.根据传入的参数获取对象
VideoEncoder* encoder = (__bridge VideoEncoder*)outputCallbackRefCon;
// 3.判断是否是关键帧
bool isKeyframe = !CFDictionaryContainsKey( (CFArrayGetValueAtIndex(CMSampleBufferGetSampleAttachmentsArray(sampleBuffer, true), 0)), kCMSampleAttachmentKey_NotSync);
// 判断当前帧是否为关键帧
// 获取sps & pps数据
if (isKeyframe)
{
// 获取编码后的信息（存储于CMFormatDescriptionRef中）
CMFormatDescriptionRef format = CMSampleBufferGetFormatDescription(sampleBuffer);
// 获取SPS信息
size_t sparameterSetSize, sparameterSetCount;
const uint8_t *sparameterSet;
CMVideoFormatDescriptionGetH264ParameterSetAtIndex(format, 0, &sparameterSet, &sparameterSetSize, &sparameterSetCount, 0 );
// 获取PPS信息
size_t pparameterSetSize, pparameterSetCount;
const uint8_t *pparameterSet;
CMVideoFormatDescriptionGetH264ParameterSetAtIndex(format, 1, &pparameterSet, &pparameterSetSize, &pparameterSetCount, 0 );
// 装sps/pps转成NSData，以方便写入文件
NSData *sps = [NSData dataWithBytes:sparameterSet length:sparameterSetSize];
NSData *pps = [NSData dataWithBytes:pparameterSet length:pparameterSetSize];
// 写入文件
[encoder gotSpsPps:sps pps:pps];
}
// 获取数据块
CMBlockBufferRef dataBuffer = CMSampleBufferGetDataBuffer(sampleBuffer);
size_t length, totalLength;
char *dataPointer;
OSStatus statusCodeRet = CMBlockBufferGetDataPointer(dataBuffer, 0, &length, &totalLength, &dataPointer);
if (statusCodeRet == noErr) {
size_t bufferOffset = 0;
static const int AVCCHeaderLength = 4; // 返回的nalu数据前四个字节不是0001的startcode，而是大端模式的帧长度length
// 循环获取nalu数据
while (bufferOffset < totalLength - AVCCHeaderLength) {
uint32_t NALUnitLength = 0;
// Read the NAL unit length
memcpy(&NALUnitLength, dataPointer + bufferOffset, AVCCHeaderLength);
// 从大端转系统端
NALUnitLength = CFSwapInt32BigToHost(NALUnitLength);
NSData* data = [[NSData alloc] initWithBytes:(dataPointer + bufferOffset + AVCCHeaderLength) length:NALUnitLength];
[encoder gotEncodedData:data isKeyFrame:isKeyframe];
// 移动到写一个块，转成NALU单元
// Move to the next NAL unit in the block buffer
bufferOffset += AVCCHeaderLength + NALUnitLength;
}
}
}
- (void)gotSpsPps:(NSData*)sps pps:(NSData*)pps
{
// 1.拼接NALU的header
const char bytes[] = "\x00\x00\x00\x01";
size_t length = (sizeof bytes) - 1;
NSData *ByteHeader = [NSData dataWithBytes:bytes length:length];
// 2.将NALU的头&NALU的体写入文件
[self.fileHandle writeData:ByteHeader];
[self.fileHandle writeData:sps];
[self.fileHandle writeData:ByteHeader];
[self.fileHandle writeData:pps];
}
- (void)gotEncodedData:(NSData*)data isKeyFrame:(BOOL)isKeyFrame
{
NSLog(@"gotEncodedData %d", (int)[data length]);
if (self.fileHandle != NULL)
{
const char bytes[] = "\x00\x00\x00\x01";
size_t length = (sizeof bytes) - 1; //string literals have implicit trailing '\0'
NSData *ByteHeader = [NSData dataWithBytes:bytes length:length];
[self.fileHandle writeData:ByteHeader];
[self.fileHandle writeData:data];
}
}
- (void)encodeSampleBuffer:(CMSampleBufferRef)sampleBuffer {
// 1.将sampleBuffer转成imageBuffer
CVImageBufferRef imageBuffer = (CVImageBufferRef)CMSampleBufferGetImageBuffer(sampleBuffer);
// 2.根据当前的帧数,创建CMTime的时间
CMTime presentationTimeStamp = CMTimeMake(self.frameID++, 1000);
VTEncodeInfoFlags flags;
// 3.开始编码该帧数据
OSStatus statusCode = VTCompressionSessionEncodeFrame(self.compressionSession,
imageBuffer,
presentationTimeStamp,
kCMTimeInvalid,
NULL, (__bridge void * _Nullable)(self), &flags);
if (statusCode == noErr) {
NSLog(@"H264: VTCompressionSessionEncodeFrame Success");
}
}
- (void)endEncode {
VTCompressionSessionCompleteFrames(self.compressionSession, kCMTimeInvalid);
VTCompressionSessionInvalidate(self.compressionSession);
CFRelease(self.compressionSession);
self.compressionSession = NULL;
}
@end