server端 -- 編碼音視訊資料為H264、AAC
這部分花了好多時間,本身就不具備這方面的相關知識,查閱了不少資料,不過關于VideoToolbox和AudioToolbox方面的編碼資料寥寥無幾,雖然網上搜尋結果看似特别多,其實一看 内容也大同小異,建議還是看看官方的文檔。
下載下傳
GitHub:
client 端:https://github.com/AmoAmoAmo/Smart_Device_Client
server端:https://github.com/AmoAmoAmo/Smart_Device_Server
另還寫了一份macOS版的server,但是目前還有一些問題,有興趣的去看看吧:https://github.com/AmoAmoAmo/Server_Mac
VideoToolbox編碼視訊資料為H264
初始化--建立session
// ----- 1. 建立session -----
int width = 640, height = 480;
OSStatus status = VTCompressionSessionCreate(NULL, width, height,
kCMVideoCodecType_H264, NULL, NULL, NULL,
didCompressH264, (__bridge void *)(self), &EncodingSession);
NSLog(@"H264: VTCompressionSessionCreate %d", (int)status);
if (status != 0)
{
NSLog(@"H264: session 建立失敗");
return ;
}
// ----- 2. 設定session屬性 -----
// 設定實時編碼輸出(避免延遲)
VTSessionSetProperty(EncodingSession, kVTCompressionPropertyKey_RealTime, kCFBooleanTrue);
VTSessionSetProperty(EncodingSession, kVTCompressionPropertyKey_ProfileLevel, kVTProfileLevel_H264_Baseline_AutoLevel);
// 設定關鍵幀(GOPsize)間隔
int frameInterval = 10;
CFNumberRef frameIntervalRef = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &frameInterval);
VTSessionSetProperty(EncodingSession, kVTCompressionPropertyKey_MaxKeyFrameInterval, frameIntervalRef);
// 設定期望幀率
int fps = 10;
CFNumberRef fpsRef = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &fps);
VTSessionSetProperty(EncodingSession, kVTCompressionPropertyKey_ExpectedFrameRate, fpsRef);
//設定碼率,上限,機關是bps
int bitRate = width * height * 3 * 4 * 8;
CFNumberRef bitRateRef = CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &bitRate);
VTSessionSetProperty(EncodingSession, kVTCompressionPropertyKey_AverageBitRate, bitRateRef);
//設定碼率,均值,機關是byte
int bitRateLimit = width * height * 3 * 4;
CFNumberRef bitRateLimitRef = CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &bitRateLimit);
VTSessionSetProperty(EncodingSession, kVTCompressionPropertyKey_DataRateLimits, bitRateLimitRef);
// Tell the encoder to start encoding
VTCompressionSessionPrepareToEncodeFrames(EncodingSession);
編碼完成回調
将來通過這個回調擷取H264資料
void didCompressH264(void *outputCallbackRefCon,
void *sourceFrameRefCon,
OSStatus status,
VTEncodeInfoFlags infoFlags,
CMSampleBufferRef sampleBuffer)
{
// NSLog(@"didCompressH264 called with status %d infoFlags %d", (int)status, (int)infoFlags); // 0 1
if (status != 0) {
return;
}
if (!CMSampleBufferDataIsReady(sampleBuffer)) {
NSLog(@"didCompressH264 data is not ready ");
return;
}
// ViewController* encoder = (__bridge ViewController*)outputCallbackRefCon;
HJH264Encoder *encoder = (__bridge HJH264Encoder*)(outputCallbackRefCon);
// ----- 關鍵幀擷取SPS和PPS ------
bool keyframe = !CFDictionaryContainsKey( (CFArrayGetValueAtIndex(CMSampleBufferGetSampleAttachmentsArray(sampleBuffer, true), 0)), kCMSampleAttachmentKey_NotSync);
// 判斷目前幀是否為關鍵幀
// 擷取sps & pps資料
if (keyframe)
{
CMFormatDescriptionRef format = CMSampleBufferGetFormatDescription(sampleBuffer);
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
NSData *sps = [NSData dataWithBytes:sparameterSet length:sparameterSetSize];
NSData *pps = [NSData dataWithBytes:pparameterSet length:pparameterSetSize];
if (encoder)
{
[encoder gotSpsPps:sps pps:pps]; // 擷取sps & pps資料
}
}
}
}
// --------- 寫入資料 ----------
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; // 傳回的nalu資料前四個位元組不是0001的startcode,而是大端模式的幀長度length
// 循環擷取nalu資料
while (bufferOffset < totalLength - AVCCHeaderLength) {
uint32_t NALUnitLength = 0;
// Read the NAL unit length
memcpy(&NALUnitLength, dataPointer + bufferOffset, AVCCHeaderLength);
// 從大端轉系統端
NALUnitLength = CFSwapInt32BigToHost(NALUnitLength);
NSData* data = [[NSData alloc] initWithBytes:(dataPointer + bufferOffset + AVCCHeaderLength) length:NALUnitLength];
[encoder gotEncodedData:data isKeyFrame:keyframe];
// Move to the next NAL unit in the block buffer
bufferOffset += AVCCHeaderLength + NALUnitLength;
}
}
}
傳入需要編碼的幀
- (void) encode:(CMSampleBufferRef )sampleBuffer
{
CVImageBufferRef imageBuffer = (CVImageBufferRef)CMSampleBufferGetImageBuffer(sampleBuffer);
// 幀時間,如果不設定會導緻時間軸過長。
CMTime presentationTimeStamp = CMTimeMake(frameID++, 1000); // CMTimeMake(分子,分母);分子/分母 = 時間(秒)
VTEncodeInfoFlags flags;
OSStatus statusCode = VTCompressionSessionEncodeFrame(EncodingSession,
imageBuffer,
presentationTimeStamp,
kCMTimeInvalid,
NULL, NULL, &flags);
if (statusCode != noErr) {
NSLog(@"H264: VTCompressionSessionEncodeFrame failed with %d", (int)statusCode);
VTCompressionSessionInvalidate(EncodingSession);
CFRelease(EncodingSession);
EncodingSession = NULL;
return;
}
}
然後就可以在上面的回調裡取得編碼後的資料,再把資料通過socket發給用戶端即可。
在每個階段都要記得測試、列印日志,不然以後找bug會很辛苦的。
這裡可以把編碼後的資料寫入本地檔案,然後用VLC工具打開,檢測編碼是否有問題。
最後不要忘記關閉編碼器
- (void)EndVideoToolBox
{
VTCompressionSessionCompleteFrames(EncodingSession, kCMTimeInvalid);
VTCompressionSessionInvalidate(EncodingSession);
CFRelease(EncodingSession);
EncodingSession = NULL;
}
另:在macOS環境下使用VideoToolbox編碼的過程在這個部落格裡:
[置頂] VideoToolbox視訊編碼——在macOS上對擷取到的視訊進行編碼的問題記錄 及YUV422轉YUV420
AudioToolbox編碼音頻資料為AAC
設定編碼參數
- (void) setupEncoderFromSampleBuffer:(CMSampleBufferRef)sampleBuffer {
AudioStreamBasicDescription inAudioStreamBasicDescription = *CMAudioFormatDescriptionGetStreamBasicDescription((CMAudioFormatDescriptionRef)CMSampleBufferGetFormatDescription(sampleBuffer));
AudioStreamBasicDescription outAudioStreamBasicDescription = {0}; // 初始化輸出流的結構體描述為0. 很重要。
outAudioStreamBasicDescription.mSampleRate = inAudioStreamBasicDescription.mSampleRate; // 音頻流,在正常播放情況下的幀率。如果是壓縮的格式,這個屬性表示解壓縮後的幀率。幀率不能為0。
outAudioStreamBasicDescription.mFormatID = kAudioFormatMPEG4AAC; // 設定編碼格式
outAudioStreamBasicDescription.mFormatFlags = kMPEG4Object_AAC_LC; // 無損編碼 ,0表示沒有
outAudioStreamBasicDescription.mBytesPerPacket = 0; // 每一個packet的音頻資料大小。如果的動态大小,設定為0。動态大小的格式,需要用AudioStreamPacketDescription 來确定每個packet的大小。
outAudioStreamBasicDescription.mFramesPerPacket = 1024; // 每個packet的幀數。如果是未壓縮的音頻資料,值是1。動态碼率格式,這個值是一個較大的固定數字,比如說AAC的1024。如果是動态大小幀數(比如Ogg格式)設定為0。
outAudioStreamBasicDescription.mBytesPerFrame = 0; // 每幀的大小。每一幀的起始點到下一幀的起始點。如果是壓縮格式,設定為0 。
outAudioStreamBasicDescription.mChannelsPerFrame = 1; // 聲道數
outAudioStreamBasicDescription.mBitsPerChannel = 0; // 壓縮格式設定為0
outAudioStreamBasicDescription.mReserved = 0; // 8位元組對齊,填0.
AudioClassDescription *description = [self
getAudioClassDescriptionWithType:kAudioFormatMPEG4AAC
fromManufacturer:kAppleSoftwareAudioCodecManufacturer]; //軟編
OSStatus status = AudioConverterNewSpecific(&inAudioStreamBasicDescription, &outAudioStreamBasicDescription, 1, description, &_audioConverter); // 建立轉換器
if (status != 0) {
NSLog(@"setup converter: %d", (int)status);
}
}
擷取編解碼器
- (AudioClassDescription *)getAudioClassDescriptionWithType:(UInt32)type
fromManufacturer:(UInt32)manufacturer
{
static AudioClassDescription desc;
UInt32 encoderSpecifier = type;
OSStatus st;
UInt32 size;
st = AudioFormatGetPropertyInfo(kAudioFormatProperty_Encoders,
sizeof(encoderSpecifier),
&encoderSpecifier,
&size);
if (st) {
NSLog(@"error getting audio format propery info: %d", (int)(st));
return nil;
}
unsigned int count = size / sizeof(AudioClassDescription);
AudioClassDescription descriptions[count];
st = AudioFormatGetProperty(kAudioFormatProperty_Encoders,
sizeof(encoderSpecifier),
&encoderSpecifier,
&size,
descriptions);
if (st) {
NSLog(@"error getting audio format propery: %d", (int)(st));
return nil;
}
for (unsigned int i = 0; i < count; i++) {
if ((type == descriptions[i].mSubType) &&
(manufacturer == descriptions[i].mManufacturer)) {
memcpy(&desc, &(descriptions[i]), sizeof(desc));
return &desc;
}
}
return nil;
}
将裝置捕獲到的音頻資料傳給編碼器
- (void) encodeSampleBuffer:(CMSampleBufferRef)sampleBuffer completionBlock:(void (^)(NSData * encodedData, NSError* error))completionBlock {
CFRetain(sampleBuffer);
dispatch_async(_encoderQueue, ^{
if (!_audioConverter) {
[self setupEncoderFromSampleBuffer:sampleBuffer];
}
CMBlockBufferRef blockBuffer = CMSampleBufferGetDataBuffer(sampleBuffer);
CFRetain(blockBuffer);
// --------- 通過CMBlockBufferGetDataPointer擷取到_pcmBufferSize和_pcmBuffer --------
OSStatus status = CMBlockBufferGetDataPointer(blockBuffer, 0, NULL, &_pcmBufferSize, &_pcmBuffer);
NSError *error = nil;
if (status != kCMBlockBufferNoErr) {
error = [NSError errorWithDomain:NSOSStatusErrorDomain code:status userInfo:nil];
}
memset(_aacBuffer, 0, _aacBufferSize);
AudioBufferList outAudioBufferList = {0};
outAudioBufferList.mNumberBuffers = 1;
outAudioBufferList.mBuffers[0].mNumberChannels = 1;
outAudioBufferList.mBuffers[0].mDataByteSize = (int)_aacBufferSize;
outAudioBufferList.mBuffers[0].mData = _aacBuffer;
AudioStreamPacketDescription *outPacketDescription = NULL;
UInt32 ioOutputDataPacketSize = 1;
// Converts data supplied by an input callback function, supporting non-interleaved and packetized formats.
// Produces a buffer list of output data from an AudioConverter. The supplied input callback function is called whenever necessary.
status = AudioConverterFillComplexBuffer(_audioConverter, inInputDataProc, (__bridge void *)(self), &ioOutputDataPacketSize, &outAudioBufferList, outPacketDescription);
NSData *data = nil;
if (status == 0) {
NSData *rawAAC = [NSData dataWithBytes:outAudioBufferList.mBuffers[0].mData length:outAudioBufferList.mBuffers[0].mDataByteSize];
NSData *adtsHeader = [self adtsDataForPacketLength:rawAAC.length];
NSMutableData *fullData = [NSMutableData dataWithData:adtsHeader];
[fullData appendData:rawAAC];
data = fullData;
} else {
error = [NSError errorWithDomain:NSOSStatusErrorDomain code:status userInfo:nil];
}
if (completionBlock) {
dispatch_async(_callbackQueue, ^{
// printf("----- audio data len = %d ----\n",(int)[data length]);
completionBlock(data, error);
});
}
CFRelease(sampleBuffer);
CFRelease(blockBuffer);
});
}
回調函數
OSStatus inInputDataProc(AudioConverterRef inAudioConverter, UInt32 *ioNumberDataPackets, AudioBufferList *ioData, AudioStreamPacketDescription **outDataPacketDescription, void *inUserData)
{
AACEncoder *encoder = (__bridge AACEncoder *)(inUserData);
UInt32 requestedPackets = *ioNumberDataPackets;
size_t copiedSamples = [encoder copyPCMSamplesIntoBuffer:ioData];
if (copiedSamples < requestedPackets) {
//PCM 緩沖區還沒滿
*ioNumberDataPackets = 0;
return -1;
}
*ioNumberDataPackets = 1;
return noErr;
}
/**
* 填充PCM到緩沖區
*/
- (size_t) copyPCMSamplesIntoBuffer:(AudioBufferList*)ioData {
size_t originalBufferSize = _pcmBufferSize;
if (!originalBufferSize) {
return 0;
}
ioData->mBuffers[0].mData = _pcmBuffer;
ioData->mBuffers[0].mDataByteSize = (int)_pcmBufferSize;
_pcmBuffer = NULL;
_pcmBufferSize = 0;
return originalBufferSize;
}
最後在需要的地方釋放編碼器
- (void) dealloc {
AudioConverterDispose(_audioConverter);
free(_aacBuffer);
}
參考文章
1. http://www.jianshu.com/p/9febe519732a#comment-13802063
2. http://www.jianshu.com/p/a671f5b17fc1
3. http://blog.csdn.net/hard_man/article/details/53511026
4. https://developer.apple.com/documentation/videotoolbox
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基于iOS的網絡音視訊實時傳輸系統(三)- VideoToolbox編碼音視訊資料為H264、AAC
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