Issue with cache on high bitrate video

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rashire Offline
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Posts: 3
Joined: Feb 2012
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Post: #1
I've been having issues with xbmc on my laptop since upgrading from 12.x to 13.x playing my 'stress test video' (A raw bluray rip into a mkv file)
I've seen the bitrate of the stream be at least 26Mbit/s and I think it's somehow messing with the buffer %filled number.

Windows 7 Laptop (amd e450)
4GB ram, 2GB free during testing
XMBC versions with issue: 13.0 release, 13.1 release, 13.2 beta2

Network share (smb)

2.4Ghz N 72Mbps, 2 feet from router

I've tried a mix of the following advanced settings:
-Putting memory between ~64MB and 256MB
-buffermode 1 or removed
-readbufferfactor 2.0, 4.0, 5.0

These are the same settings I use on my FireTV and my Windows 8 pc and the file plays smoothly.

The thing I find weird is when it is stuttering playback, it looks to me like XBMC has plenty of cache for smooth playback, but still throws the error "cache filled before reaching required amount for continuous play"

[Image: nBG95ejI]

In this screenshot the video is playing at ~15 Mbps, and shows a cache size of 64MB, which with rough math should be good for ~30 seconds of playback. It also shows 0% next to cache, which I'm assuming means it thinks it has no cache.

If I play a different encoded source with a lower bitrate 1.5~2Mbit everything works smoothly, the cache fills close enough to the advanced config settings, the % almost always shows 100.

I'm not entirely sure my issue linked to the bitrate of the video, but that's all I have to go on at this time. I'm able to play the video seamlessly on my FireTV at the same time as Laptop is stuttering through playback, so I don't believe it is network bandwidth or disk throughput that are to blame.

I will post a debug log tonight for this, in the mean time please let me know if there is any additional information I can provide.
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rashire Offline
Junior Member
Posts: 3
Joined: Feb 2012
Reputation: 0
Post: #2
Took a bit longer than I thought to get back on this, here is my log. Still having issue with playback.
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rashire Offline
Junior Member
Posts: 3
Joined: Feb 2012
Reputation: 0
Post: #3
So, I actually think I've more or less resolved my issue. It looks like my wifi channel got congested, I was only getting 28Mbit/s on file transfers, and I saw the video bitrate go as high as 38Mbit. I moved my wireless off channel 6 and on to channel 1 and I now get 40~44Mbit/s off wireless.

I'm still confused as to why cacheing isn't filling to an appropriate level when the buffer is depleted. Why the video stutters when codec info shows a decent level of cache. Or why when the buffer is empty the pause isn't longer to fill the cache up more before resuming playback.

Setting a large cache has always helped me with xbmc and playback over slower networks (VPN etc) and works great on my android devices, it still just doesn't seem to be calculating right.
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