iOS h264硬编码

从这里抄过来的：https://github.com/LevyGG/iOS-H.264-hareware-encode-and-decode/blob/master/VTDemoOniPad/H264HwEncoderImpl.h

#import <Foundation/Foundation.h>

@import AVFoundation;

@protocol H264HwEncoderImplDelegate <NSObject>

- (void)gotSpsPps:(NSData*)sps pps:(NSData*)pps;

- (void)gotEncodedData:(NSData*)data isKeyFrame:(BOOL)isKeyFrame;

@end

@interface H264HwEncoderImpl : NSObject 

- (void) initWithConfiguration;

- (void) initEncode:(int)width  height:(int)height;

- (void) encode:(CMSampleBufferRef )sampleBuffer; 

- (void) End;

@property (weak, nonatomic) NSString *error;

@property (weak, nonatomic) id<H264HwEncoderImplDelegate> delegate;

@end

#import "H264HwEncoderImpl.h"

@import VideoToolbox;

@import AVFoundation;

@implementation H264HwEncoderImpl

{

    VTCompressionSessionRef EncodingSession;

    dispatch_queue_t aQueue;

    CMFormatDescriptionRef  format;

    CMSampleTimingInfo * timingInfo;

    BOOL initialized;

    int  frameCount;

    NSData *sps;

    NSData *pps;

}

@synthesize error;

- (void) initWithConfiguration

{

    EncodingSession = nil;

    initialized = true;

    aQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);

    frameCount = 0;

    sps = NULL;

    pps = NULL;

}

// VTCompressionOutputCallback（回调方法）  由VTCompressionSessionCreate调用

void didCompressH264(void *outputCallbackRefCon, void *sourceFrameRefCon, OSStatus status, VTEncodeInfoFlags infoFlags,

CMSampleBufferRef sampleBuffer )

{

    NSLog(@"didCompressH264 called with status %d infoFlags %d", (int)status, (int)infoFlags);

    if (status != 0) return;

    if (!CMSampleBufferDataIsReady(sampleBuffer))

    {

        NSLog(@"didCompressH264 data is not ready ");

        return;

    }

   H264HwEncoderImpl* encoder = (__bridge H264HwEncoderImpl*)outputCallbackRefCon;

   // Check if we have got a key frame first

    bool keyframe = !CFDictionaryContainsKey( (CFArrayGetValueAtIndex(CMSampleBufferGetSampleAttachmentsArray(sampleBuffer, true), 0)), kCMSampleAttachmentKey_NotSync);

   if (keyframe)

   {

        CMFormatDescriptionRef format = CMSampleBufferGetFormatDescription(sampleBuffer);

       // CFDictionaryRef extensionDict = CMFormatDescriptionGetExtensions(format);

       // Get the extensions

       // From the extensions get the dictionary with key "SampleDescriptionExtensionAtoms"

       // From the dict, get the value for the key "avcC"

        size_t sparameterSetSize, sparameterSetCount;

        const uint8_t *sparameterSet;

        OSStatus statusCode = CMVideoFormatDescriptionGetH264ParameterSetAtIndex(format, 0, &sparameterSet, &sparameterSetSize, &sparameterSetCount, 0 );

        if (statusCode == noErr)

        {

            // Found sps and now check for pps

            size_t pparameterSetSize, pparameterSetCount;

            const uint8_t *pparameterSet;

            OSStatus statusCode = CMVideoFormatDescriptionGetH264ParameterSetAtIndex(format, 1, &pparameterSet, &pparameterSetSize, &pparameterSetCount, 0 );

            if (statusCode == noErr)

            {

                // Found pps

                encoder->sps = [NSData dataWithBytes:sparameterSet length:sparameterSetSize];

                encoder->pps = [NSData dataWithBytes:pparameterSet length:pparameterSetSize];

                if (encoder->_delegate)

                {

                    [encoder->_delegate gotSpsPps:encoder->sps pps:encoder->pps];

                }

            }

        }

    }

    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;

        while (bufferOffset < totalLength - AVCCHeaderLength) {           

            // Read the NAL unit length

            uint32_t NALUnitLength = 0;

            memcpy(&NALUnitLength, dataPointer + bufferOffset, AVCCHeaderLength);            

            // Convert the length value from Big-endian to Little-endian

            NALUnitLength = CFSwapInt32BigToHost(NALUnitLength);

            NSData* data = [[NSData alloc] initWithBytes:(dataPointer + bufferOffset + AVCCHeaderLength) length:NALUnitLength];

            [encoder->_delegate gotEncodedData:data isKeyFrame:keyframe];

            // Move to the next NAL unit in the block buffer

            bufferOffset += AVCCHeaderLength + NALUnitLength;

        }

    }

}

- (void) initEncode:(int)width  height:(int)height // 仅调用一次

{

    dispatch_sync(aQueue, ^{

       CFMutableDictionaryRef sessionAttributes = CFDictionaryCreateMutable(

                                                                             NULL,

                                                                             0,

                                                                             &kCFTypeDictionaryKeyCallBacks,

                                                                             &kCFTypeDictionaryValueCallBacks);

        // bitrate 只有当压缩frame设置的时候才起作用，有时候不起作用，当不设置的时候大小根据视频的大小而定

//        int fixedBitrate = 2000 * 1024; // 2000 * 1024 -> assume 2 Mbits/s

//        CFNumberRef bitrateNum = CFNumberCreate(NULL, kCFNumberSInt32Type, &fixedBitrate);

//        CFDictionarySetValue(sessionAttributes, kVTCompressionPropertyKey_AverageBitRate, bitrateNum);

//        CFRelease(bitrateNum);    

        // CMTime CMTimeMake(int64_t value, int32_t timescale)当timescale设置为1的时候更改这个参数就看不到效果了

//        float fixedQuality = 1.0;

//        CFNumberRef qualityNum = CFNumberCreate(NULL, kCFNumberFloat32Type, &fixedQuality);

//        CFDictionarySetValue(sessionAttributes, kVTCompressionPropertyKey_Quality, qualityNum);

//        CFRelease(qualityNum);

        //貌似没作用

//        int DataRateLimits = 2;

//        CFNumberRef DataRateLimitsNum = CFNumberCreate(NULL, kCFNumberSInt8Type, &DataRateLimits);

//        CFDictionarySetValue(sessionAttributes, kVTCompressionPropertyKey_DataRateLimits, DataRateLimitsNum);

//        CFRelease(DataRateLimitsNum);

 // 创建编码

        OSStatus status = VTCompressionSessionCreate(NULL, width, height, kCMVideoCodecType_H264, sessionAttributes, NULL, NULL, didCompressH264, (__bridge void *)(self),  &EncodingSession);

        NSLog(@"H264: VTCompressionSessionCreate %d", (int)status);

        if (status != 0)

        {

            NSLog(@"H264: Unable to create a H264 session");

            error = @"H264: Unable to create a H264 session";

            return ;

        }

        //设置properties（这些参数设置了也没用）

        VTSessionSetProperty(EncodingSession, kVTCompressionPropertyKey_RealTime, kCFBooleanTrue);

        VTSessionSetProperty(EncodingSession, kVTCompressionPropertyKey_ProfileLevel, kVTProfileLevel_H264_High_5_2);

        VTSessionSetProperty(EncodingSession, kVTCompressionPropertyKey_AllowFrameReordering, kCFBooleanFalse);

        // 启动编码

        VTCompressionSessionPrepareToEncodeFrames(EncodingSession);

    });

}

// 从控制的AVCaptureVideoDataOutputSampleBufferDelegate代理方法中调用至此

- (void) encode:(CMSampleBufferRef )sampleBuffer // 频繁调用

{

     dispatch_sync(aQueue, ^{

          frameCount++;

            // Get the CV Image buffer

            CVImageBufferRef imageBuffer = (CVImageBufferRef)CMSampleBufferGetImageBuffer(sampleBuffer);

//            CVPixelBufferRef pixelBuffer = (CVPixelBufferRef)CMSampleBufferGetImageBuffer(sampleBuffer);

            // Create properties

            CMTime presentationTimeStamp = CMTimeMake(frameCount, 1); // 这个值越大画面越模糊

//            CMTime duration = CMTimeMake(1, DURATION);

            VTEncodeInfoFlags flags;

            // Pass it to the encoder

            OSStatus statusCode = VTCompressionSessionEncodeFrame(EncodingSession,

                                                         imageBuffer,

                                                         presentationTimeStamp,

                                                         kCMTimeInvalid,

                                                         NULL, NULL, &flags);

            // Check for error

            if (statusCode != noErr) {

                NSLog(@"H264: VTCompressionSessionEncodeFrame failed with %d", (int)statusCode);

                error = @"H264: VTCompressionSessionEncodeFrame failed ";

                // End the session

                VTCompressionSessionInvalidate(EncodingSession);

                CFRelease(EncodingSession);

                EncodingSession = NULL;

                error = NULL;

                return;

            }

            NSLog(@"H264: VTCompressionSessionEncodeFrame Success");

       });

}

- (void) End

{

    // Mark the completion

    VTCompressionSessionCompleteFrames(EncodingSession, kCMTimeInvalid);

    // End the session

    VTCompressionSessionInvalidate(EncodingSession);

    CFRelease(EncodingSession);

    EncodingSession = NULL;

    error = NULL;

}

@end