Stuttering with sftp mount
#1
Hi all,

I've tried it all, and I still get stuttering with an sftp mount on xbmc 13.1 (openelec 4.0.5 on raspberry pi), so I'm asking for help here.

I've tried playing with buffers in advancedsettings: from force buffering (buffermode set to 1) to no buffer (set to 3). Buffer size from 5MB to 60MB; and read buffer factor from 1 to 8. Nothing helps, I get stuttering and the symptoms are always the same. If I enable the codec info overlay, I essentially see the following:

After some initial buffering, vf and af go to 100%, aq is close to 100% and vq is (suspiciously?) 0%. The reported buffer size varies according to the settings, but in general didn't make a difference. After some playback, vf starts decreasing until it drops to 0%, at that point af starts decreasing too, together with aq. When they reach about 0% playback stops for a while, until all buffers are re-filled, and the usual stuttering problem starts again. CPU is about 60% during playback, and 20% during forced pauses, so I think it's not a horsepower issue.

Please not that in openelec v3 I had the same problem, but if I mounted my remote share with sshfs (rather than via the XBMC interface) then I did not experience stuttering. (I have a steady 10Mb/s connection, and I experience stuttering on streams that take about 0.2Mb/s to stream.)

What else can I try? Any suggestion and comment are welcome!
Reply
#2
I believe sftp is problematic for xbmc on all platforms:
http://forum.xbmc.org/showthread.php?tid=182698

I think a different protocol may be needed (until xbmc moves to libssh2).
Reply
#3
Thanks for the quick and very useful answer!

The thread you pointed me to gives finally a reasonable explanation to the problem: the bottleneck is the low bandwidth induced by the libssh implementation used by xbmc; that's why playing with buffers didn't help, but using sshfs did.

Okay, I'll look into alternative protocols, and will keep an eye open on xbmc-ssh developments. Thanks again!
Reply
#4
Just to confirm, switching to HTTPS solved all stuttering issues.

As a downside, HTTPS is a bit less secure than SSH, in that it uses password authentication, rather than public key one; and I'm not sure xbmc performs strict server certificate validation, like a browser would do. (Does xbmc accept self signed certificates, for example?)
Reply

Logout Mark Read Team Forum Stats Members Help
Stuttering with sftp mount0