[mythtv] SVN 8106 playback pauses for prebuffering often

Daniel Kristjansson danielk at cuymedia.net
Sun Dec 4 18:38:05 UTC 2005

On Sun, 2005-12-04 at 13:18 -0500, Jesse Crews wrote:
> I'm not sure I follow this part. The HARD reserve appears to be 
> calculated from num_xvmc_surf + XVMC_SHOW_NUM, right?

> The monochrome OSD uses 1 surface, correct?
Yep, you can increase this when using Via XvMC for smoother playback though.

> With this nv, we have 8 surfaces.
> 1 for OSD
> 1 for the XVMC_SHOW_NUM
> These are hard reserved.
> Then, we take that value (2) + PRE_NUM (2) + POST_NUM (1) + SHOW_NUM (1)
> soft reserved = 6. Correct?
Nope, PRE should be 1 not 2. A B-frame needs one previous I or P frame
and one post (future) I or P frame.

> Now, GetPreBufferGoal returns 2 instead of 3.
If PRE is 2, but it should be 1.

> So, It looks like we're actually prebuffering _fewer_ frames, but we 
> have an extra surface reserved for display. Is this correct, or have I 
> misread something? It does seem to work better this way, and the 
> machine didn't lock up, although I can't say that I took the time to 
> run it for more than about 20 minutes.
There is an extra surface reserved for display in the soft-reserve.
But it may not be needed anymore, after [8062].

> Chromakey OSD works like a charm. I'm personally going to use it instead.
FYI It's a work in progress; but it does basically work.

-- Daniel

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