[mythtv-users] HDMI capture card with linux drivers
Douglas Peale
Douglas_Peale at comcast.net
Fri Apr 16 06:58:50 UTC 2010
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Douglas Peale wrote:
> Raymond Wagner wrote:
> I missed the beginning of this discussion. I understand you want to
> record HDMI signals. I'm assuming you want to do this because that is
> what you get out of your cable box. You do realize that this data is
> encrypted don't you? How do you plan on decrypting it? The only time it
> might not be encrypted would be if it was broadcast in clear QAM in the
> first place. In that case you would be much better off just saving the
> already compressed data before it gets uncompressed and sent over the
> HDMI cable.
Never mind, I found the history of this thread.
It turns out that the HDMI is doing some compression on the data, they
are using YUV 4:2:2 which means they are throwing away half of the color
information.
So the calculation is more like (1920 * 1080) pixels * 10 bits/sample *
2 samples/pixel * 30 frames/sec * 1/8 bytes/bit =155,520,000 bytes/second.
Still to much for a single drive. They do recommend an array though.
This card is fine for video editing, but useless for a PVR. This device
does not decrypt HDMI signals, cable boxes will be downresing their
component outputs, and anything that is not encrypted or downres, can be
captured with a clear QAM tuner.
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