> For the complete documentation index, see [llms.txt](https://philm.gitbook.io/philm-ios-wiki/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://philm.gitbook.io/philm-ios-wiki/mei-zhou-yue-du/gpuimage-yuan-ma-jie-du-shi-san.md). # GPUImage源码解读(十三) GPUImageMovieWriter 方法不是很多，但是方法都比较长，内部处理也相对比较复杂。这里只给出了常见的方法。如果需要录制视频，可以仔细阅读 ``` //// 初始话音频参数，如编码格式、声道数、采样率、码率 - (void)setHasAudioTrack:(BOOL)newValue audioSettings:(NSDictionary *)audioOutputSettings; { _hasAudioTrack = newValue; if (_hasAudioTrack) { if (_shouldPassthroughAudio) { // Do not set any settings so audio will be the same as passthrough audioOutputSettings = nil; } else if (audioOutputSettings == nil) { AVAudioSession *sharedAudioSession = [AVAudioSession sharedInstance]; double preferredHardwareSampleRate; if ([sharedAudioSession respondsToSelector:@selector(sampleRate)]) { preferredHardwareSampleRate = [sharedAudioSession sampleRate]; } else { #pragma clang diagnostic push #pragma clang diagnostic ignored "-Wdeprecated-declarations" preferredHardwareSampleRate = [[AVAudioSession sharedInstance] currentHardwareSampleRate]; #pragma clang diagnostic pop } AudioChannelLayout acl; //初始化音频通道 bzero( &acl, sizeof(acl)); acl.mChannelLayoutTag = kAudioChannelLayoutTag_Mono; //设置为单通道模式 //配置音频参数 audioOutputSettings = [NSDictionary dictionaryWithObjectsAndKeys: [ NSNumber numberWithInt: kAudioFormatMPEG4AAC], AVFormatIDKey, [ NSNumber numberWithInt: 1 ], AVNumberOfChannelsKey, [ NSNumber numberWithFloat: preferredHardwareSampleRate ], AVSampleRateKey, [ NSData dataWithBytes: &acl length: sizeof( acl ) ], AVChannelLayoutKey, //[ NSNumber numberWithInt:AVAudioQualityLow], AVEncoderAudioQualityKey, [ NSNumber numberWithInt: 64000 ], AVEncoderBitRateKey, nil]; /* AudioChannelLayout acl; bzero( &acl, sizeof(acl)); acl.mChannelLayoutTag = kAudioChannelLayoutTag_Mono; audioOutputSettings = [NSDictionary dictionaryWithObjectsAndKeys: [ NSNumber numberWithInt: kAudioFormatMPEG4AAC ], AVFormatIDKey, [ NSNumber numberWithInt: 1 ], AVNumberOfChannelsKey, [ NSNumber numberWithFloat: 44100.0 ], AVSampleRateKey, [ NSNumber numberWithInt: 64000 ], AVEncoderBitRateKey, [ NSData dataWithBytes: &acl length: sizeof( acl ) ], AVChannelLayoutKey, nil];*/ } self.assetWriterAudioInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeAudio outputSettings:audioOutputSettings]; [assetWriter addInput:assetWriterAudioInput]; assetWriterAudioInput.expectsMediaDataInRealTime = NO; } else { // Remove audio track if it exists } } ``` 视频设置方法 ``` //视频输入源 setting - (void)initializeMovieWithOutputSettings:(NSDictionary *)outputSettings; { isRecording = NO; self.enabled = YES; NSError *error = nil; self.assetWriter = [[AVAssetWriter alloc] initWithURL:movieURL fileType:fileType error:&error]; if (error != nil) { NSLog(@"Error: %@", error); if (failureBlock) { failureBlock(error); } else { if(self.delegate && [self.delegate respondsToSelector:@selector(movieRecordingFailedWithError:)]) { [self.delegate movieRecordingFailedWithError:error]; } } } // Set this to make sure that a functional movie is produced, even if the recording is cut off mid-stream. Only the last second should be lost in that case. //默认值为10S // _captureMovieFileOutput.movieFragmentInterval = kCMTimeInvalid assetWriter.movieFragmentInterval = CMTimeMakeWithSeconds(1.0, 1000); // use default output settings if none specified //设置输出视频的宽高 if (outputSettings == nil) { NSMutableDictionary *settings = [[NSMutableDictionary alloc] init]; [settings setObject:AVVideoCodecH264 forKey:AVVideoCodecKey]; [settings setObject:[NSNumber numberWithInt:videoSize.width] forKey:AVVideoWidthKey]; [settings setObject:[NSNumber numberWithInt:videoSize.height] forKey:AVVideoHeightKey]; outputSettings = settings; } // custom output settings specified else { NSString *videoCodec = [outputSettings objectForKey:AVVideoCodecKey]; NSNumber *width = [outputSettings objectForKey:AVVideoWidthKey]; NSNumber *height = [outputSettings objectForKey:AVVideoHeightKey]; NSAssert(videoCodec && width && height, @"OutputSettings is missing required parameters."); if( [outputSettings objectForKey:@"EncodingLiveVideo"] ) { NSMutableDictionary *tmp = [outputSettings mutableCopy]; [tmp removeObjectForKey:@"EncodingLiveVideo"]; outputSettings = tmp; } } /* NSDictionary *videoCleanApertureSettings = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithInt:videoSize.width], AVVideoCleanApertureWidthKey, [NSNumber numberWithInt:videoSize.height], AVVideoCleanApertureHeightKey, [NSNumber numberWithInt:0], AVVideoCleanApertureHorizontalOffsetKey, [NSNumber numberWithInt:0], AVVideoCleanApertureVerticalOffsetKey, nil]; NSDictionary *videoAspectRatioSettings = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithInt:3], AVVideoPixelAspectRatioHorizontalSpacingKey, [NSNumber numberWithInt:3], AVVideoPixelAspectRatioVerticalSpacingKey, nil]; NSMutableDictionary * compressionProperties = [[NSMutableDictionary alloc] init]; [compressionProperties setObject:videoCleanApertureSettings forKey:AVVideoCleanApertureKey]; [compressionProperties setObject:videoAspectRatioSettings forKey:AVVideoPixelAspectRatioKey]; [compressionProperties setObject:[NSNumber numberWithInt: 2000000] forKey:AVVideoAverageBitRateKey]; [compressionProperties setObject:[NSNumber numberWithInt: 16] forKey:AVVideoMaxKeyFrameIntervalKey]; [compressionProperties setObject:AVVideoProfileLevelH264Main31 forKey:AVVideoProfileLevelKey]; [outputSettings setObject:compressionProperties forKey:AVVideoCompressionPropertiesKey]; */ float bitRate = 87500.0f * 8.0f; int frameInterval = 24; NSDictionary *compressionSettings = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithFloat:bitRate], AVVideoAverageBitRateKey, [NSNumber numberWithInt:frameInterval*2], AVVideoMaxKeyFrameIntervalKey, nil]; NSDictionary *videoCompressionSettings = [NSDictionary dictionaryWithObjectsAndKeys: AVVideoCodecH264, AVVideoCodecKey, AVVideoScalingModeResizeAspectFill, AVVideoScalingModeKey, [NSNumber numberWithInteger:videoSize.width], AVVideoWidthKey, [NSNumber numberWithInteger:videoSize.height], AVVideoHeightKey, // square format compressionSettings, AVVideoCompressionPropertiesKey, nil]; self.assetWriterVideoInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoCompressionSettings]; assetWriterVideoInput.expectsMediaDataInRealTime = YES; // You need to use BGRA for the video in order to get realtime encoding. I use a color-swizzling shader to line up glReadPixels' normal RGBA output with the movie input's BGRA. NSDictionary *sourcePixelBufferAttributesDictionary = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithInt:kCVPixelFormatType_32BGRA], kCVPixelBufferPixelFormatTypeKey, [NSNumber numberWithInt:videoSize.width], kCVPixelBufferWidthKey, [NSNumber numberWithInt:videoSize.height], kCVPixelBufferHeightKey, nil]; // NSDictionary *sourcePixelBufferAttributesDictionary = [NSDictionary dictionaryWithObjectsAndKeys: [NSNumber numberWithInt:kCVPixelFormatType_32ARGB], kCVPixelBufferPixelFormatTypeKey, // nil]; assetWriterPixelBufferInput = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:assetWriterVideoInput sourcePixelBufferAttributes:sourcePixelBufferAttributesDictionary]; //添加视频输入源 [assetWriter addInput:assetWriterVideoInput]; } ``` ``` //处理音频 - (void)processAudioBuffer:(CMSampleBufferRef)audioBuffer; { if (!isRecording) { return; } @autoreleasepool { // if (_hasAudioTrack && CMTIME_IS_VALID(startTime)) // 有音频数据才处理 if (_hasAudioTrack) { CFRetain(audioBuffer); //当前时间戳 CMTime currentSampleTime = CMSampleBufferGetOutputPresentationTimeStamp(audioBuffer); // if (CMTIME_IS_INVALID(startTime)) // { // runSynchronouslyOnContextQueue(_movieWriterContext, ^{ // if ((audioInputReadyCallback == NULL) && (assetWriter.status != AVAssetWriterStatusWriting)) // { // [assetWriter startWriting]; // } // [assetWriter startSessionAtSourceTime:currentSampleTime]; // startTime = currentSampleTime; // }); // } //音频输入不准备接受更多的媒体数据 if (!assetWriterAudioInput.readyForMoreMediaData && _encodingLiveVideo) { NSLog(@"1: Had to drop an audio frame: %@", CFBridgingRelease(CMTimeCopyDescription(kCFAllocatorDefault, currentSampleTime))); if (_shouldInvalidateAudioSampleWhenDone) { CMSampleBufferInvalidate(audioBuffer); } CFRelease(audioBuffer); return; } previousAudioTime = currentSampleTime; //if the consumer wants to do something with the audio samples before writing, let him. //回调音频数据 if (self.audioProcessingCallback) { //need to introspect into the opaque CMBlockBuffer structure to find its raw sample buffers. CMBlockBufferRef buffer = CMSampleBufferGetDataBuffer(audioBuffer); CMItemCount numSamplesInBuffer = CMSampleBufferGetNumSamples(audioBuffer); AudioBufferList audioBufferList; CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(audioBuffer, NULL, &audioBufferList, sizeof(audioBufferList), NULL, NULL, kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment, &buffer ); //passing a live pointer to the audio buffers, try to process them in-place or we might have syncing issues. for (int bufferCount=0; bufferCount < audioBufferList.mNumberBuffers; bufferCount++) { SInt16 *samples = (SInt16 *)audioBufferList.mBuffers[bufferCount].mData; self.audioProcessingCallback(&samples, numSamplesInBuffer); } } // NSLog(@"Recorded audio sample time: %lld, %d, %lld", currentSampleTime.value, currentSampleTime.timescale, currentSampleTime.epoch); // 写入音频block void(^write)() = ^() { // while( ! assetWriterAudioInput.readyForMoreMediaData && ! _encodingLiveVideo && ! audioEncodingIsFinished ) { // NSDate *maxDate = [NSDate dateWithTimeIntervalSinceNow:0.5]; // NSLog(@"audio waiting..."); // [[NSRunLoop currentRunLoop] runUntilDate:maxDate]; // } if (!assetWriterAudioInput.readyForMoreMediaData) { NSLog(@"2: Had to drop an audio frame %@", CFBridgingRelease(CMTimeCopyDescription(kCFAllocatorDefault, currentSampleTime))); } else if(assetWriter.status == AVAssetWriterStatusWriting) { if (![assetWriterAudioInput appendSampleBuffer:audioBuffer]) NSLog(@"Problem appending audio buffer at time: %@", CFBridgingRelease(CMTimeCopyDescription(kCFAllocatorDefault, currentSampleTime))); } else { //NSLog(@"Wrote an audio frame %@", CFBridgingRelease(CMTimeCopyDescription(kCFAllocatorDefault, currentSampleTime))); } // 标记不被使用 if (_shouldInvalidateAudioSampleWhenDone) { CMSampleBufferInvalidate(audioBuffer); } CFRelease(audioBuffer); }; // runAsynchronouslyOnContextQueue(_movieWriterContext, write); if( _encodingLiveVideo ) { runAsynchronouslyOnContextQueue(_movieWriterContext, write); } else { // 否则，直接写入 write(); } } } } ``` --- # Agent Instructions This documentation is published with GitBook. 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