On Saturday 18 November 2006 02:04, Corey Fehr wrote:
> Does anybody have a good handle on the layout of the pvr-350 board,
> I was hoping for some insight from those more informed than I? I have
> been playing with scaling of the mpeg video for output via
> /dev/video16 on the PVR-350. If I use the 'ivtvctl -f' option to
> perform some scaling on the decoder I would expect that the resizing
> operation would be taking place on the decoding side right before the
> signal is output from the card but this is not the case since the
> encoded mpeg stream that the *PC* receives is even scaled.
>
> It was my (obviously faulty) understanding that the saa7115 would be
> handling the mpeg decoding side exclusively and therefore the video
> inspected prior to /dev/video16 output would be unaffected. I have
> also run the tests without using the "ivtvctl -f" call and instead
> using discrete "ivtvctl -g" calls to affect only the saa7115
> registers and it is the same result.
>
> a) Can somebody fill me in on the details of the architecture in that
> the "decoder" register settings are changing the incoming "encoded"
> mpeg stream? b) Does anybody know of a way to off load the resizing
> operation to *only* on the decoding side so that I can still grab
> full 720x480 incoming frames on the PC and output a scaled variant
> via /dev/video16?
>
> I know that there is currently a big push to get new releases out but
> any help would be appreciated. Thanks again.
The saa7115 takes the TV antenna analog input and digitizes it and if
needed scales it. That is the input for the MPEG encoder which produces
an MPEG program stream. If you put that into the MPEG decoder it is
decoded to the saa7127 which takes the YUV frames and converts them to
an analog signal for the TV-out. The saa7127 cannot do scaling. As far
as I know there is no way to scale the output of the MPEG decoder.
Hans
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