Time Warner Cable HD quality?

[gopheralex]

Does anyone know if TWC recompresses any of its clearQAM stuff at all, or is it the exact same bitstream as OTA? I've heard of some cable providers recompressing HD material to save bandwidth.

[mhz40]

Depending on the instantaneous bit rates of all the programs on the QAM channel at any point in time, there may be a few seconds each hour that the incoming bit rate of one mpeg stream or another is reduced, but they are all virtually the same in and out. It's gotta be that way to protect the integrity of the transport stream. You can not fit 8.0001 pounds of mpeg potatoes into a 8 pound mpeg transport sack... so to speak - - or the whole thing falls apart. The bit rate shaping function is used as a guard against oversubscription ever happening.
The format of the picture is not compromised (720p or 1080i) in any way.

[gopheralex]

I thought I had heard somewhere that some cable providers recompress their HD streams to save bandwidth. But it looks like you are right. I just recorded off the QAM feed and compared it to the OTA feed for the major networks in the area, and it looks like they are all transmitting at roughly the same data rate, give or take a little bit. I suspect the difference is due to VBR encoding, or maybe it was just my sloppy testing methodology.

[VoidXero]

The format of the picture is not compromised (720p or 1080i) in any way.

Well I don't think anyone is suggesting that the resolution gets reduced during bit shaping. It's the additional compression that introduces more artifacts (yes the original TS has some as well) that most people object to.