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[linux-dvb] Re: converting PES to TS while reading from (multiple)/dev/ost/demux0
Felix Domke writes:
> > Which is AFAIK a rather nasty limitation of the current API.
> > As far as I know there is no way to find out where exactly
> > payload_unit_start_indicator bits were set when you read from
> > a demux device. You need to read TS packets from dvr if you want
> > to have the payload_unit_start_indicator bits. But dvr
> > only supports one concurrent opener...
> It *IS* a nasty limitation.
>
> I would prefer:
>
> DMX_SET_PES_FILTER
>
> with two new options:
>
> a.) type, like "TRANSPORT" (all 188 bytes), "PAYLOAD" (like the deafault)
This should not be too much work to add.
> and maybe a "read one payload unit as once", maybe with a header (with the
> size and - maybe - things like the adaption field, but maybe this is exactly
> what AV_PES did.. i don't know. so maybe just "PAYLOAD" and if you want to
> get the PUSI-flag "TRANSPORT")
To get the size would be a problem, because then the whole PES would
have to be buffered additionally to the normal buffering until the
size can be determined. And those PES packets can get quite large.
AV_PES also did not deliver adaptation fields. You will not be
able to get the original adaptation fields (or TS packets) with
the AV7110 cards anyway.
> b.) the estimated datarate, or more low-level, the amount of data which
> should be available until an interrupt occurs.
>
> The absence of b.) leads to high system load if you break up a fast stream
> (Video/Audio, EIT) into many small packets, or, if you use a big "buffer
> size" (or "interrupt threshold") to the problem that you cannot read ONE
> small packet (for low datarate streams, like PAT/PMT or even NIT).
OK, but influencing such an interrupt threshold is not possible with
all hardware.
> A huge company did a nice api for using their chipset with Linux, it very
> much like the OST-Api, but has this new options. I really miss them in the
> OST.
Which company is that and is the API description available?
Ralph
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