Are you trying with the 'Audio Only' transcoder profile? That's the one to use if you already have H.264 video and the audio is speex. With that profile the video will just be passed through untouched,
and the audio will get converted to AAC.
The live stream that would be transcoded and created would be played back as the following example URL:
for flash playback:
HLS for iOS device playback
The filename that would show up as recorded in the content folder, in this case, would resemble:
and perhaps some date and time stamps in the file name as well.