AC-3 encoding

Hello,

I had a AC-3 stream,it had following specification.From (Media Info)

Audio

Format :AC-3Format/Info :Audio Coding 3Mode extension :CM (complete main)Format settings, Endianness :LittleDuration :2mn 31sBit rate mode :ConstantBit rate :448 KbpsChannel(s) :2 channelsChannel positions :Front: L RSampling rate :48.0 KHzBit depth :16 bitsCompression mode :LossyStream size :8.10 MiB (100%)
I wrapped this stream in to MOV using ffmpeg.
Audio

ID :1Format :E-AC-3Format/Info :Audio Coding 3Codec ID :ec-3Duration :2s 675msBit rate mode :VariableBit rate :25.4 MbpsChannel(s) :5 channelsChannel positions :Front: L C R, Side: L RSampling rate :48.0 KHzBit depth :16 bitsCompression mode :LossyStream size :8.10 MiB (100%)Language :English




The command which i used given below.
ffmpeg.exe -i original.ac3 -acodec copy -ar 48000 -ac 2 -ab 448k -f mov new.mov

why i get wrong channel info in the new stream. Also any specific lib in ffmpeg needs to specify for AC-3.?

Thanks in Advance!
Dave.