[eshelon]

I've been following this thread for quite some time and wanted to share my setup and experiences thus far as I've painfully learned that the details really do matter..

First, my setup:

NAS: Unraid server w/ Couchpotato and Sickbeard, Sabnzb, and a few other apps
Media Server 1: Apple TV 2 with iOS 5.0.2, Jailbroken running final stable build of XBMC Eden (11.0)
Media Server 2: Apple TV 2 with iOS 5.0.2, Jailbroken running latest nightly build (Jan 30th) of XBMC Frodo (12.0)
Network Setup: Apple Airport Extreme Wireless Router (dual-band N)
Connectivity to Media Servers: I have three configurations that I've tested: hard wired ethernet, wireless, and ethernet over power (using trendnet power adapters).

Connectivity from Media Servers to AV Equipment:

Living Room Apple TV 2
Connectivity to Network: Have attempted wired, wireless, and wired over power (using trendnet powerline adapters)
Connectivity to LG TV: HDMI
Connectivity to Harmon Kardon AVR-500:
Original Setup: From LG TV Optical Out to AVR Optical Input
note: I originally used this setup for two reasons. In XBMC Eden (11.0) I wasn't able to connect Optical from the ATV2 to my receiver and get audio to work. I had to pass through my TV through HDMI first. In the latest build from Frodo, I was able to get this to work with a direct optical connection from the ATV2 to the AVR. Another thing to note is that if you try to use both HDMI and Optical for audio output at the same time (e.g. your TV speaker through HDMI and your receiver with optical) you WILL notice an audio delay between the two input types. You shouldn't do this.
second note: I haven't tried going back to wireless since the frodo/optical cable change so I can't say whether or not buffering issues would return as prevalent or not yet...I may test this again later.
IMPORTANT: if you are passing audio through a TV and back to a receiver via optical right now and are having buffering issues, this resolved a NUMBER of those problems for me just by changing the cabling.

Bedroom Apple TV 2
Connectivity to Network: Wireless N
Connectivity to Samsung TV: HDMI
No AVR Unit in Bedroom ;-(
note: buffering issues up here didn't seem as bad as the living room but it depends on the content. The bedroom in my house is on the second story and my wireless router is in the basement. Still, I actually don't have actually too many complaints about that right now

I've been having streaming issues of various kinds with various file types. Someone else in this thread brought up a similar issue where high intensity content (streaming at a higher bitrate) tends to increase the likelihood for a buffering issue to occur.

My Unraid server supports the NFS, SMB, and AFP protocols and I've tried them all.

My story is simple: My first setup was using both ATV2s with Eden and connecting to content over wireless and SMB protocol. Most content would work fine and all of my videos are H.264. Buffering issues were there for almost every movie but they were relatively intermittent (once to twice per movie) and I noticed that I rarely would have issues with TV Shows or lower definition content.

However, higher definition content would prove to be nearly unwatchable (1080p). A 7.5GB 1080p movie buffers a lot so I decided to try a few other things to fix it.

I have all my settings per the FAQ (16-bit audio, airplay turned off my ATV natively, can't find the thumbnails thing everyone's talking about, etc).

Bottom line?

If your audio receiver doesn't support HDMI, you will need to connect optically directly to the ATV to avoid buffering issues. Never pass your audio through another source before getting to the receiver.

Unfortunately because I attempted too many fixes all at once, I'm really not entirely sure whether or not that alone solved my problem. It could be that in combination with the other tweaks/upgrades I did.

And to the XBMC dev team, keep up the great work. Frodo is a huge improvement and I can't wait to see what you guys come up with next! And with the new h.265 standard getting ratified, I think we have lots of exciting things to expect from this team!!

By the way...

I tried all protocols prior to upgrading to Frodo and upon switching from SMB to NFS, I saw a major increase in buffering frequency (from once per movie to once every 1-2 minutes). Changing back to SMB and I was still having the same problems. Now that I'm not having problems in my living room (and using NFS), I'm updating my bedroom ATV2 to Frodo (stable build) and going to just try that over NFS. Will update again with the results.

Oh, and before switching back to NFS, I actually even tried AFP and that was even worse than either NFS or SMB.

Question to the community for those using UnRAID for the NAS:

My UnRAID host:
System: ASUSTeK - C60M1-I
CPU: AMD C-60 APU with RadeonTM HD Graphics - 1 GHz
Cache: 128 kB
Memory: 2 GB - 667 MHz
Network: 1000Mb/s - Full Duplex
Connections: Four

When I'm looking at the UnRAID stats, my processor is at about 40-50% when streaming a single 720p video and doesn't actually even get much higher than that when we're streaming two videos at once. Network looks ok as well. Streaming that 720p video over that powerline ethernet shows me we're bouncing between 10-16mbps which to me isn't all that great. Edit: I removed my comment about my NAS having a lot of receive traffic because I didn't realize it was getting some auto-dls going from Couchpotato.

However, I am definitely concerned about the RAM. On a fresh boot, the NAS sits at about 1.5gb in use with between 300-500mb free. But quickly after starting a movie, the amount of free memory is practically nothing and I'm wondering if 2GB is not enough for a NAS to stream to multiple hosts with content ranging from SD to 1080p (e.g., can I logically support 2 concurrent 1080p streams from source files between 6-10GB in size?).

Another Update
I happen to be watching a 720p copy of Tron Legacy right now that generates a high bitrate. In those high intensity sequences, I used to get a lot of audio choppiness and buffering. Now I get FAR less buffering, but the video is still getting jittery during high intensity sequences. Now this is a 720p video that's only a 3.6GB MKV.

Regarding AC3/DTS Audio Support
Prior to making the configuration updates aforementioned, I would have issues when I would enable DTS audio support in XBMC, even though my harmon kardon AVR-500 supports DTS. When I turned it on, I would get intermittent audio blipping and a high rate of buffering. If I left AC3 support on without DTS, I would get better audio if the source file supported it, but again, i'd suffer some framerate issues on certain content (intermittent).

NOW, with the cabling change, frodo update (latest nightly build), and still using powerline ethernet for network connectivity, and using NFS protocol, I'm able to use both DTS and AC3 in XBMC without buffering issues (so far I've only tested 720p content though). I'm going to test some 1080p in a few here and see what happens!