Try to determine the SystemBitrate value from the Source value, on most assets created by AMS encoder, the bitrate value is part of the source name (schema is x.mp4)
If the source manifest has an additional audio track that is identical to one of the video tracks, the audio track can be removed (fixes #250)
Make sure that tracks that use the same source get consolidated, only the track with the highest bitrate should be taken
I've added some manifest patching to the code:
Please review.