Windows Media Audio V2 (WAVE_FORMAT_WMAUDIO2 0x161) wrong nBlockAlign

Question

Hello i'm trying to cut some audio on wma file from the beginning without reencoding it by removing samples programmatically.

My questions:
1. is it possible to cut encoded audio by nBlockAlign bytes without loosing decoded data of the next sample?
2. are directshow samples dependent on each other in wma?

My tests:

Audio format:
subtype: {00000161-0000-0010-8000-00AA00389B71}

wFormatTag: 353
nChannels: 2
nSamplesPerSec:44100
nAvgBytesPerSec: 16002
nBlockAlign: 5945
wBitsPerSample: 16

decoder specific data:
00 88 00 00 0F 00 00 00 00 00

Directshow Samples are 5945 bytes length ( it's equal to nBlockAlign).

If i have two samples each has 5945 bytes length

WM Audio Decoder DMO gives the following times and data count
start time(ms)/ stop time(ms)/ data size(bytes)
0              58             10240
58         150            16384
150         232            14336
232         278            8192
278        371           16384
371         464            16384
464         510            8192


if i give to decoder only first it gives:
start time(ms)/ stop time(ms)/ data size(bytes)
0              58             10240
58           150            16384
150         232            14336
232         278            8192


if i give to decoder only second

start time(ms)/ stop time(ms)/ data size(bytes)

46                    139                  16384
139                  185                  8192


The difference in decoded data between two samples decoded together and independently decoded is 16384 bytes

Does this mean nBlockAlign is wrong? And how this value can be calculated?

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Stanislav Mikhailenko