In case of variable bit rate codecs or codecs whose bit rate is not a multiple of 8 bits, the number of samples being read from the file can not be always matched with the specified TSignalRead.Length property. If ForceLength is True and the value of the Length property can not be matched an exception will be raised. The position within the file with variable bit rate can be defined only approximately (in steps of 0.1 seconds for example.) 

When the data blocks are read without explicit changes to the RecordPosition, all data blocks are read consecutively without overlapping or loosing any samples. (But the Length property will vary between consecutive calls.

TSignalRead Properties