[vdr] possible busy loop in cDvbPlayer::Action?

Martin Wache M.Wache at gmx.net
Sun Jul 3 10:34:05 CEST 2005


Udo Richter schrieb:
> Luca Olivetti wrote:
> 
>>I also wonder how is it
>>possible that vdr hasn't enough data to give to the device: no matter
>>how big the buffer, once it is filled it should stay more or less full,
>>unless you're at the end of the file.
> 
> 
> One guess: On playback start, buffers are empty and can accept lots of
> data. This could result in some busy loops until enough data is read to
> fill the buffer.
> 
> If, for some reason, the disk read requires much CPU time, then the busy
> loop will actually slow down the disk reading too.
> 
> Maybe, in case of softdevice, this is oscillating: A busy file reader
> takes CPU from decoding, causing decoding to stall. And as soon as the
> decoder is catching up, maybe by dropping frames, the file buffers run
> empty causing the file reader to busy loop again. (speculative, though)

I guess this is a possible scenario, at least it explains the symptoms
quite acuratly.
Hmm, to finally solve this I guess we have to wait until Klaus answers.
I think he is now on his holidays, right? So I'll wait until he is back.
But thanks for your answers, at least I know now that the softdevice is
not the only one which has problems like this.

Bye,
Martin



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