ios - 使用 gstreamer 通过网络将 ARFrame CVPixelBuffer 作为字节数组发送时崩溃

Question

我想通过网络发送 ARFrame 像素缓冲区数据，我在下面列出了我的设置。使用此设置，如果我尝试在几帧后在 gstreamers C 代码中发送帧应用程序崩溃，但如果我改为发送相机的 AVCaptureVideoDataOutput 像素缓冲区，则流工作正常。我已将 AVCaptureSession 的像素格式类型设置为

kCVPixelFormatType_420YpCbCr8BiPlanarFullRange

所以它复制了 ARFrame 给出的相同类型。请帮助我找不到任何解决方案。很抱歉，如果我的英语不好或者我错过了什么，请向我询问。

我的设置

1. 从 ARKit 的 didUpdateFrame 委托获取 ARFrame 的 pixelBuffer
2. 使用 VTCompressionSession 编码为 h264

- (void)SendFrames:(CVPixelBufferRef)pixelBuffer :(NSTimeInterval)timeStamp
{
  size_t width = CVPixelBufferGetWidth(pixelBuffer);
  size_t height = CVPixelBufferGetHeight(pixelBuffer);

  if(session == NULL)
  {
      [self initEncoder:width height:height];
  }

  CMTime presentationTimeStamp = CMTimeMake(0, 1);

  OSStatus statusCode = VTCompressionSessionEncodeFrame(session, pixelBuffer, presentationTimeStamp, kCMTimeInvalid, NULL, NULL, NULL);
  if (statusCode != noErr) {

      // End the session
      VTCompressionSessionInvalidate(session);
      CFRelease(session);
      session = NULL;
      return;
  }

  VTCompressionSessionEndPass(session, NULL, NULL);
}

- (void) initEncoder:(size_t)width  height:(size_t)height
{
  OSStatus status = VTCompressionSessionCreate(NULL, (int)width, (int)height, kCMVideoCodecType_H264, NULL, NULL, NULL, OutputCallback, NULL, &session);

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

  if (status != noErr)
  {
    NSLog(@"Unable to create a H264 session");
    return ;
  }

  VTSessionSetProperty(session, kVTCompressionPropertyKey_RealTime, kCFBooleanTrue);
  VTSessionSetProperty(session, kVTCompressionPropertyKey_ProfileLevel, kVTProfileLevel_H264_Baseline_AutoLevel);
  VTCompressionSessionPrepareToEncodeFrames(session);
}

3. 从回调中获取sampleBuffer，将其转换为基本流

void OutputCallback(void *outputCallbackRefCon, void *sourceFrameRefCon, OSStatus status, VTEncodeInfoFlags infoFlags,CMSampleBufferRef sampleBuffer)
{
    if (status != noErr) {
        NSLog(@"Error encoding video, err=%lld", (int64_t)status);
        return;
    }

    if (!CMSampleBufferDataIsReady(sampleBuffer))
    {
        NSLog(@"didCompressH264 data is not ready ");
        return;
    }

    // In this example we will use a NSMutableData object to store the
    // elementary stream.
    NSMutableData *elementaryStream = [NSMutableData data];

    // This is the start code that we will write to
    // the elementary stream before every NAL unit
    static const size_t startCodeLength = 4;
    static const uint8_t startCode[] = {0x00, 0x00, 0x00, 0x01};

    // Write the SPS and PPS NAL units to the elementary stream 
    CMFormatDescriptionRef description = CMSampleBufferGetFormatDescription(sampleBuffer);


    // Find out how many parameter sets there are
    size_t numberOfParameterSets;
    int AVCCHeaderLength;
    CMVideoFormatDescriptionGetH264ParameterSetAtIndex(description,
                                                       0, NULL, NULL,
                                                       &numberOfParameterSets,
                                                       &AVCCHeaderLength);



    // Write each parameter set to the elementary stream
    for (int i = 0; i < numberOfParameterSets; i++) {
        const uint8_t *parameterSetPointer;
        int  NALUnitHeaderLengthOut = 0;

        size_t parameterSetLength;
        CMVideoFormatDescriptionGetH264ParameterSetAtIndex(description,
                                                           i,
                                                           &parameterSetPointer,
                                                           &parameterSetLength,
                                                           NULL, &NALUnitHeaderLengthOut);

        // Write the parameter set to the elementary stream
        [elementaryStream appendBytes:startCode length:startCodeLength];
        [elementaryStream appendBytes:parameterSetPointer length:parameterSetLength];

    }


    // Get a pointer to the raw AVCC NAL unit data in the sample buffer
     size_t blockBufferLength;
     uint8_t *bufferDataPointer = NULL;
     size_t lengthAtOffset = 0;
     size_t bufferOffset = 0;


    CMBlockBufferGetDataPointer(CMSampleBufferGetDataBuffer(sampleBuffer),
                                bufferOffset,
                                &lengthAtOffset,
                                &blockBufferLength,
                                (char **)&bufferDataPointer);

    // Loop through all the NAL units in the block buffer
    // and write them to the elementary stream with
    // start codes instead of AVCC length headers

    while (bufferOffset < blockBufferLength - AVCCHeaderLength) {
        // Read the NAL unit length
        uint32_t NALUnitLength = 0;
        memcpy(&NALUnitLength, bufferDataPointer + bufferOffset, AVCCHeaderLength);
        // Convert the length value from Big-endian to Little-endian
        NALUnitLength = CFSwapInt32BigToHost(NALUnitLength);

        // Write start code to the elementary stream
        [elementaryStream appendBytes:startCode length:startCodeLength];
        // Write the NAL unit without the AVCC length header to the elementary stream
        [elementaryStream appendBytes:bufferDataPointer + bufferOffset + AVCCHeaderLength
                               length:NALUnitLength];
        // Move to the next NAL unit in the block buffer
        bufferOffset += AVCCHeaderLength + NALUnitLength;
    }

    char *bytePtr = (char *)[elementaryStream mutableBytes];
    long maxSize = (long)elementaryStream.length;

    CMTime presentationtime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);

    vidplayer_stream(bytePtr, maxSize, (long)presentationtime.value);
}

标签： iosobjective-cvideo-streaminggstreamerarkit