Fwd: [linux-dvb] genlock

Morgan Tørvolt morgan.torvolt at gmail.com
Mon Jan 15 15:02:24 CET 2007


Sending this to the list also, for future reference...

---------- Forwarded message ----------
From: Morgan Tørvolt <morgan.torvolt at gmail.com>
Date: 15-Jan-2007 17:33
Subject: Re: [linux-dvb] genlock
To: Samuel Goto <samuelgoto at gmail.com>


Hi Sam

What you are making is basically a mux? You put audio and video
together to one TS stream? In that case, my only advice would be to
use stuffing. Lower the combined bitrate from your sources to less
than the output bitrate, and insert stuffing TS packets to compensate
so that you get the correct output bitrate. I believe there really is
no other way of doing it, as it is close to impossible to get a 100%
stable raw mpeg datarate. There is also a possibility that your
mpeg-encoder does some stuffing to get the correct bitrate. You could
remove these first if you want...

Depending on the mux, professional muxes does different things when
fed with too much data. Some just drops random packages (BAD!, i can
mention certain brands, some does this even when the total is less
than the muxrate, as long as one service is higher than configured),
others drop packages from the one with too high bitrate, others allow
for the higher bitrate, but starts dropping from the service with too
high bitrate when the total exceeds the mux-rate. How you want to
implement this is your choice, but I would suggest to allow for some
excessive datarate to keep clients happy =)

-Morgan-

On 15/01/07, Samuel Goto <samuelgoto at gmail.com> wrote:
> Hi everyone,Any
>
>         I am developing a dvb s1 transmitter. Its input is a MPEG TS from a
> mpeg encoder and its output is a DVB S1 stream to the RF satellite.
>
>         I am having problems synchronizing the input bit rate to the output
> baud rate and I was wondering if anyone could help me out on this list ( or
> suggest me a better one =) ). The transmitter works for 7 to 8 minutes, but
> then its output buffer overflows ( showing that there is a small difference
> from the input rate to the necessary output rate ).
>
>         Thanks for your attention,
>
>         Cya, Sam
>
> --
> f u cn rd ths u cn b a gd prgmr !
> _______________________________________________
> linux-dvb mailing list
> linux-dvb at linuxtv.org
> http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
>
>



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