private static void CheckAudioFormat(IMFMediaType mediaType, IDictionary<FormatCheckElement, Tuple<bool, object>> ret) { var subType = mediaType.GetSubType(); var isAac = subType == MFMediaType.AAC; ret.Add(FormatCheckElement.AudioCodec, Tuple.Create<bool, object>(isAac, subType)); if (isAac) { var aacObjectType = mediaType.GetAacObjectType(); ret.Add(FormatCheckElement.AudioAacObjectType, Tuple.Create<bool, object>(aacObjectType == 2, aacObjectType)); var channels = mediaType.GetChannel(); ret.Add(FormatCheckElement.AudioChannel, Tuple.Create<bool, object>(channels == 1 || channels == 2, channels)); } }