Capturing cable TV: are sources equivalent (cable box vs M-card tuner)?

[Nickster]

Just curious- if one was planning to capture cable TV HD shows (1080i with 5.1 audio) in the US with an HDMI capture device like the Colossus, would a cable box HDMI output be identical in quality to the output recorded from a M-card tuner device like the Ceton InfiniTV or the HDHomerun Prime?

If anyone has experience comparing the two, I would be interested if there is any difference (I assume there is no difference since I guess a cable box is an M-card tuner of sorts, but I don't have a cable box right now to make a comparison). I of course would want to start with the better quality output device if there is any significant difference between the two.

[jagabo]

The transport stream of unencrypted channels can be saved directly when using a cablecard tuner. That is the best you're going to get for those channels. I'm not aware of any crack for encrypted transport streams. So encrypted channels have to be output via HDMI and captured by a capture device (keep in mind you will need and HDCP stripper). The HDMI output of a cable box and computer should be the same unless one of the devices "enhances" the picture.

By the way, I have a SiliconDust HDHomerun Prime accessed by several PCs in the house.

[Nickster]

Thanks jagabo. That's what I was thinking but wanted to make certain.

[Brad]

Are video cards smart enough to output 1080i 1:1? Meaning, disabling their hardware deinterlacing and outputting the original fields in order directly. I would also be concerned about any display jitter, and of course ensure that you are getting no tearing.

[usually_quiet]

The transport stream of unencrypted channels can be saved directly when using a cablecard tuner. That is the best you're going to get for those channels. I'm not aware of any crack for encrypted transport streams. So encrypted channels have to be output via HDMI and captured by a capture device (keep in mind you will need and HDCP stripper). The HDMI output of a cable box and computer should be the same unless one of the devices "enhances" the picture.

By the way, I have a SiliconDust HDHomerun Prime accessed by several PCs in the house.

I don't think you fully explained the situation.

In your case, the "copy freely" files may be the same as the unencrypted (clear QAM) channels. On the other hand, every channel in my Comcast package is encrypted, but apparently I do have lots of "copy freely" channels. There is a hidden diagnostic menu for my cable box that lets me see whether the channel being tuned is "copy once" protected or not. So far every one I have looked as is "copy freely". If the stream for the channel decrypted by the CableCARD is marked "copy freely" it can be recorded as a standard TS file by most PVR software and Windows Media Center stores it as an unprotected WTV file.

Problems only arise when channels are marked "copy once or "copy never". In the case of "copy once", only Windows Media Center will be able to record the stream and it is stored as a "protected" WTV file. The only way to remove the copy protection on those files is to re-record them with a capture device connected to the PC.

Channels marked "copy never" won't record at all if someone is using a CableCARD tuner. It is necessary to capture the output from a cable box to record those.

[jagabo]

Are video cards smart enough to output 1080i 1:1? Meaning, disabling their hardware deinterlacing and outputting the original fields in order directly.

Yes, if you choose to.

I would also be concerned about any display jitter, and of course ensure that you are getting no tearing.

No jitter, no tearing here.