Changing media encoding properties for prepareTranscodeAsync() in

Question

Hi,
I am working with the transcoding sample. I modified the app to alter the media encoding properties. i.e give custom values for parameters like, bits per sample, fps, channel count, width, height etc. and create a transcoded output file. Input file is in WMV and output file is in MP4. i use CreateMp4() API to create the encoding profile. 

When I use prepareFileTranscodeAsync() with media encoding profile which has "bitspersample" value 8 for audio(audio of input file has 16 bits per sample), I get the transcoded output video which has same bits sample as that of the input (16 bits per sample). Change in the media encoding profile values does not seem take effect in the output video when prepareFileTranscodeAsync(). Is there a way to transcode using the custom values to these properties?
Thanks.