I'm coming to this thread late (Dad finally passed away at 95 in Arizona; last week was invested in going over his financials) but if we're talking 720x480 then MOST scenes will look pretty much perfect at, say, 8Mb/sec. But throw a scene of ocean waves or 10,000 screaming fans in an arena at the encoder and it will probably show some blockiness. Any scene that begins to look like fine-grained "noise" to the encoder will tend to show blockiness because the worst possible encoding situation is random noise.

So I guess I don't understand what gain there is by going to an astronomically high bitrate if we're showing typical scenes.

I believe you answered your own question. The broadcasters want material that won't show the blockiness under any situations. Of course, if the material was already compressed below that level then "expanding" it back to the higher bitrate won't help. It'll just help it become less worse than using a lower bitrate.

I don't know the reason they want this bit rate. (yes this is sd data rate, HD starts at 30Mbps min.) It's double (the bit rate) since last week. Last weeks stuff looked as good as I would expect. But after 20 years of supplying ads to them, I'll just do as they ask.

Started out delivering on 3/4sp , that's tape for you youngsters out there, That tape was dubbed over to another MASTER 3/4 tape, that tape was dubbed to a head end tape and physically placed in a head end 3/4 deck for playback, one master tape per channel, per city . In some locations there were 10 to 15 3/4 decks, all waiting for a timecode signal so they could play back the ads. During a mechanical breakdown (theirs) I even delivered a VHS master. Results must have been ok 'cause we are all still in business.

The stories about this stuff is legend, let me tell you about the time they sent out a master tape for a live sports event, all the way across the state, without checking the master. Naw, that's a story for another time.

Thanks for all the replies. So far the latest ad I emailed seems to be OK. Let's hope.

J

videoTguy,
"ridiculously compression rates makes no sense at all".??
Sorry, but as of about a year ago it made perfect sense to cable companies. Think: putting 6 pounds into a five pound bag....maximizing available bandwidth by compressing content to "acceptable quality". This is for SD spots...HD uploaded material may have slightly higher specs.
It's not just Charter/Time Warner systems either...I'm quite sure Comcast as well as smaller providers do it as well. This is a well known standard industry practice at the local level for commercial insertions, and my comments are not meant to denigrate any provider.
I've had many years of good relations with these companies and am more than a little finicky about the proper display of my clients' spots, but these are the facts of life when producing commercials for local markets. It's a good idea to make a copy of your program material rendered out at the mpeg bitrate the cable company compresses to. If this looks good, you can be reasonably sure that it will look good on-air.
Communication with the engineering dept. will go a long way toward getting the best quality from your material in their service areas.
Hope this helps,
Ken