get h264/hevc parameter set from cmsamplebuffer

GetParameterSet.swift

import AVFoundation

// Get H264/HEVC Parameter Set
private func getParameterSet(_ sampleBuffer: CMSampleBuffer) -> Data {
    var parameterSet = Data()
    let codecStartCode =  [UInt8](arrayLiteral: 0x00, 0x00, 0x00, 0x01)
    parameterSet.append(contentsOf: codecStartCode)
    let description = CMSampleBufferGetFormatDescription(sampleBuffer)!
    
    var numParams = 0
    CMVideoFormatDescriptionGetH264ParameterSetAtIndex(description, parameterSetIndex: 0, parameterSetPointerOut: nil, parameterSetSizeOut: nil, parameterSetCountOut: &numParams, nalUnitHeaderLengthOut: nil)
    //CMVideoFormatDescriptionGetHEVCParameterSetAtIndex(description, parameterSetIndex: 0, parameterSetPointerOut: nil, parameterSetSizeOut: nil, parameterSetCountOut: &numParams, nalUnitHeaderLengthOut: nil)
 
    // in H264 Stream, index 0 == sps, 1 == pps
    // in HEVC Stream, index 0 == vps, 1 == sps, 2 == pps
    for index in 0 ..< numParams {
        var parameterSetPointer: UnsafePointer<UInt8>!
        var parameterSetLength = 0
        CMVideoFormatDescriptionGetH264ParameterSetAtIndex(description, parameterSetIndex: index, parameterSetPointerOut: &parameterSetPointer, parameterSetSizeOut: &parameterSetLength, parameterSetCountOut: nil, nalUnitHeaderLengthOut: nil)
        
        parameterSet.append(contentsOf: codecStartCode)
        parameterSet.append(parameterSetPointer!, count: parameterSetLength)
    }
    
    return parameterSet
}