iOS CoreMedia-CMVideoFormatDescriptionCreateFromHEVCParameterSets API中'扩展'参数的合格<key，value>对的列表是什么

如何解决iOS CoreMedia-CMVideoFormatDescriptionCreateFromHEVCParameterSets API中'扩展'参数的合格<key，value>对的列表是什么

我想使用以下列表创建CMVideoFormatDescriptionRef

VPS
SPS
PPS
前缀SEI
后缀SEI

我是从HEVC编码的比特流中获得的。

我尝试并成功使用Apple的core-media API创建了格式说明

CM_EXPORT
Osstatus CMVideoFormatDescriptionCreateFromHEVCParameterSets(
    CFAllocatorRef CM_NULLABLE allocator,/*! @param allocator
                                                                                 CFAllocator to be used when creating the CMFormatDescription. Pass NULL to use the default allocator. */
    size_t parameterSetCount,/*! @param parameterSetCount
                                                                                 The number of parameter sets to include in the format description. This parameter must be at least 3. */
    const uint8_t * CM_NONNULL const * CM_NONNULL parameterSetPointers,/*! @param parameterSetPointers
                                                                                 Points to a C array containing parameterSetCount pointers to parameter sets. */
    const size_t * CM_NONNULL parameterSetSizes,/*! @param parameterSetSizes
                                                                                 Points to a C array containing the size,in bytes,of each of the parameter sets. */
    int NALUnitHeaderLength,/*! @param NALUnitHeaderLength
                                                                                 Size,of the NALUnitLength field in a HEVC video sample or HEVC parameter set sample. Pass 1,2 or 4. */
    CFDictionaryRef CM_NULLABLE extensions,/*! @param extensions   Dictionary of extension key/value pairs. Keys are always CFStrings.
                                                                                Values are always property list objects (ie. CFData,CFString,CFArray,CFDictionary,CFDate,CFBoolean,or CFNumber). Can be NULL. */
    CM_RETURNS_RETAINED_ParaMETER CMFormatDescriptionRef CM_NULLABLE * CM_NONNULL formatDescriptionOut )    /*! @param formatDescriptionOut
                                                                                 Returned newly-created video CMFormatDescription */
                            API_AVAILABLE(macos(10.13),ios(11.0),tvos(11.0),watchos(6.0));

但是，我对 6th @param extensions 感到好奇，该参数采用NULL或CFDictionaryRef作为参数，我想知道该参数的合格键，或者要知道的任何链接关于他们。