You may have an Apple TV and many AVI movies store on PC or Mac. Most of there AVI movies you want to sync to Apple TV are files with audio channels as 5.1. If you want to put and transfer these 5.1 AVI videos to Apple TV via iTunes and still keep its 6 channels surround sound, you need convert 5.1 AVI movies to H.264 AAC MP4 with 5.1 channels for Apple TV.
How to transcode/convert 5.1 AVI to Apple TV H.264 AAC (*.MP4) and Keep Surround Sound?
Free download Aunsoft AVI to Apple TV Converter, install and run it. (The program allows you to convert 5.1 AVI, 5.1 MKV, 5.1 MTS, 5.1 M2TS, etc files to Apple TV H.264 AAC (*.MP4) with 5.1 channels, and still keep its good quality
Step 1: Import or add the AVI files with 6 channels into this program.
Step 2: Set the output video format as Apple TV H.264 AAC (*.MP4) with 5.1 channels.You can select the output video format Apple TV H.264 (*.MP4), Apple TV h.264 720*480 (*.MP4), or Apple TV H.264 1280*720 (.mp4) from Apple TV in the drop-down list “Format”.
Then you can click “Settings” to confirm the audio codec is AAC, audio channels (5.1). The default settings is just AAC with 5.1 channels, see as follow:
Step 3: Select the output folder by clicking Folder icon of Output.
Step 4: Click the “Convert” button to start converting 5.1 AVI to Apple TV (*.mp4) with surround sound.
Quickly you will get your converted Apple TV (*.mp4) files with 5.1 channels and the audio/video synch correctly and perfectly.