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18 lines
1.1 KiB
Plaintext
18 lines
1.1 KiB
Plaintext
Here are some tips on how to use the modulator
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cards.
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After you set the tuning parameter of the modulator you open the
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/dev/adaptor<X>/mod<Y> of your modulator and write into it.
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You should write a steady stream of transport packets with the
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rate given by the modulation. The easiest way to keep a steady rate
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is to write as much as the device will receive until it blocks. In that
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way you ensure that the device will not get an underrun of data and
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you can use the acceptance rate as a guide for you input rate.
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All you should do is to correct the PTS of your transport stream according
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to the calculated packet rate and use a buffer that assures that you are
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always ready to write as sson as the modulator device allows it.
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E.g you have a circular output buffer that you fill to say 50% and than start
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writing into the device in a seperate thread. You feed the output buffer
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with you input TS and see that it does not underrun, you may need to insert
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empty packets to do that. The output thread should always have enough data
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to write to the device as soon as it no longer blocks. |