avformat/flvdec: read the correct bits into the tag type
from the flv spec, the flvtag define the tagtype as one byte,
the spec desc is:
Reserved UB[2] Reserved for FMS, should be 0
Filter UB[1] Indicates if packets are filtered.
0 = No pre-processing required.
1 = Pre-processing (such as decryption) of the packet is
required before it can be rendered.
Shall be 0 in unencrypted files, and 1 for encrypted
tags.
See Annex F. FLV Encryption for the use of filters.
TagType UB[5] Type of contents in this tag. The following types are
defined:
8 = audio
9 = video
18 = script data
Signed-off-by: Steven Liu <qi.liu@chinacache.com> Signed-off-by: Michael Niedermayer <michaelni@gmx.at>