[mythtv-users] MythTV, seeking ahead / behind, NFS, and bandwidth usage

[Isaac Richards]

On Sunday 01 August 2004 04:40 pm, Blammo[doh] wrote:
> Two machines in this cluster, both Athlon XP 2400's, plenty of ram, both
> running KnoppMyth R4V4, one backend with two PVR-250's, and a frontend with
> Nvidia card hooked together on a 100M cisco switch. /myth mounted over NFS
> from the backend.
>
> Problem:
>
> When seeking forward / backward in MPEG2 streams, from recorded TV, I seem
> to be running out of ethernet bandwidth. I don't notice this AT ALL in the
> "Video" section with mplayer, just in the TV section. Anything over say 3X
> seems to have diminishing returns. All the way up at 8x or 16x, checking
> the switchports shows about 50 - 60meg of traffic running. The load on the
> backend seems to be pretty low, as does the load on the front end. It just
> seems like the frontend isn't getting data fast enough.
>
> It appears to me, that the frontend has to read the whole file, to seek
> ahead / behind in the file, at 1x, 1.5x 2x etc faster. It doesn't appear to
> "seek" or "jump" at all ahead, rather reading the whole thing.
>
> I'm just wondering if anyone else has run into this, and what they did to
> fix it. Obviously transcoding to a low bit-rate MPEG4 would help. It makes
> me wonder whether the front end couldn't be a little smarter about the file
> reading, take less NFS bandwidth in the process. After all, mplayer has no
> trouble skipping ahead, etc.
>
> Thoughts?

You're confusing fast-forwarding (what you are doing) with seeking (what you 
want to be doing).

Isaac