[linux-dvb] Re: FF cards alter PTS'?

[Klaus Schmidinger <Klaus.Schmidinger@cadsoft.de>]

Ralph Metzler wrote:
> 
> Johannes Stezenbach writes:
>  > Ralph Metzler wrote:
>  > > Johannes Stezenbach writes:
>  > >
>  > >  > The av7110 destroys the adaptation fields if you record and watch
>  > >  > at the same time (record with DMX_PES_OTHER to prevent this). However,
>  > >  > the DMX_GET_STC should give you correct values. Also, AFAIK the PES
>  > >  > header is not altered by the av7110 or firmware, so the PTS should
>  > >
>  > > Video PES which are being decoded are taken apart. ES and PTS (lower
>  > > 32 Bit only) go into separate ring buffers.
>  > >
>  > >  > be correct. Or maybe the 33rd bit of the STC/PTS gets lost?
>  > >
>  > > Yes, for decoded video always.
>  >
>  > I thought the TS packets are grabbed from the TPP before they
>  > reach the decoder? So we should get unaltered PES?
> 
> No, AFAIK, you cannot get all packets of the video PID before they reach
> the decoder. The TPP does all the writing into the ES ring buffer by
> itself. The only exception seem to be packets with PUSI bit set. They are
> parsed by the firmware ROM. It also handles the PTS buffer. Here one
> can also find the infamous PTS length counting bug which (indirectly)
> caused the "jerking in playback" bug.
> But this is all from disassembling the firmware ROM and lots of
> guessing. There is no documentation on this.
> 
> Maybe there is a better way to do this. One could do more rewriting in
> the EOP FIQ (as I did to get the time shifting working). One
> could always handle live viewing like playback, writing to the
> decode buffers in software. This would give you the complete video
> packets. It would probably also get rid of TPP lockups which seem to
> be caused by bad video streams from weak channels or during tuning.
> But is it really worth putting more work into this old hardware?
> 
> Ralph

Well, AFAICS this "old hardware" is very widely used, and the main
platform VDR is designed for. And judging from the download volume
every new version of the "linvdr" distribution causes (according to
Mirko Dölle) VDR must be rather popular ;-) So I guess this hardware
will still be in use for quite a while, and I can see no adequate
replacement around - but that may be due to my lack of market
overview...

Many people (including myself) have several of these DVB cards and
would sure appreciate any improvement that could be done on them
(at least in order to make them run more stable and reliable).

Klaus


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