Film-Tech Forum ARCHIVE: Variations in Cable vs Broadcast Audio

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Posted by Frank Angel (Member # 248) on 07-14-2008, 12:43 AM:

It was quite awhile before I subscribed to CableVision, the cable franchise here in Brooklyn, mainly because I had a direct line-of-sight view of the World Trade Center & the transmitter antenna and now the Empire State Bldg where they transmit from presently. That's nearly like having a hard wire from the TV studios direct to my TV receiver. Perfect, ghost-less pictures....no need for cable. But I finally sucummed to sign up for cable service recently mainly because my lady has stuff she wants to see on the women's cable channels.

But here's the question -- when I had broadcast, the audio levels did go up slightly on commercials, but not so much as to make me get annoyed at the increase. With cable, on the other hand, the variation has become so dramatic that it makes us run for the remote. With broadcast it wasn't nearly as bad. How can this be?

Why would the cable transmission differ from what the broadcast studio sending it out? It it manipulated by the cable company? And if so, to what end? It seems illogical to me that there would be any incentive at all for the cable company to raise the volume levels of commercials in network or local NY station transmissions, but there is absolutely no doubt that this is what is happening.

Granted, I haven't played a cable reception simultaneously with the same broadcast reception, to measure this differential, but I certainly know from observation that as soon as I changed to cable, this dramatic difference was real and immediately apparent.

Has anyone else experienced this volume increase that I find unique to cable retransmission of network broadcasts? If so, how do you think this is accomplished and more importantly, why?

Posted by Randy Stankey (Member # 64) on 07-14-2008, 01:10 AM:

I was once told it was because the sound in commercials isn't compressed/limited but the programs are.

However, it doesn't make sense to me that cable companies would compress more or less than over the air broadcasters. [Shrug]

Posted by Frank Angel (Member # 248) on 07-14-2008, 02:03 AM:

....or that they would change the compression for only certain parts of the broadcast. That would mean they are actively manipulating the audio manually, which also wouldn't make sense as that would cost them MONEY (technician's time).

UNLESS.....they are inserting their own commercials, much like local stations do to the network feeds. Although I thought it was illegal for cable companies to alter the originating stations' feeds in any way.

Posted by Joe Redifer (Member # 3) on 07-14-2008, 02:51 AM:

Get in the habit of muting ALL commercials, broadcast or cable like I do.

Posted by Louis Bornwasser (Member # 3063) on 07-14-2008, 06:30 AM:

Cable boys routinely add their own commercials to all channels. Louis

Posted by Rick Raskin (Member # 1561) on 07-14-2008, 06:47 AM:

Content providers insert a digital "cue" to activate ad insertion equipment at the local head end. What I find peculiar is some national commercials will blow you away with volume while others in the same program feed are at normal levels. Joe says it -- mute all commercials.

Posted by Tim Reed (Member # 137) on 07-14-2008, 07:22 AM:

The program material is Dolby, the spots aren't. [Razz]

Posted by Bobby Henderson (Member # 840) on 07-14-2008, 08:28 AM:

If you're getting HD over digital cable or satellite some of the commercials actually can be Dolby Digital 5.1. It's especially odd if the program is 2.0 channel stereo and then a commercial or network ID spot jumps in with 5.1 audio. There may be a serious volume jump as well. The Universal HD and MHD channels can be annoying for how loud their network ID spots can be versus the program that is playing.

Posted by Lyle Romer (Member # 1266) on 07-14-2008, 10:35 AM:

Get a DVR and skip all the commercials!

Posted by Jesse Skeen (Member # 586) on 07-14-2008, 12:48 PM:

If they're channels you're paying for, there shouldn't be ANY commercials!

Wonder if Cablevision still has this channel:

http://www.youtube.com/watch?v=IIbzZl41OQo

Posted by Paul Mayer (Member # 355) on 07-14-2008, 01:40 PM:

In theaters we deal with the same issue when playing loud trailers.

TV spots these days are recorded with lots of compression to keep all of the signal swings right up against the limit. That's why many of them sound so loud yet on a VU meter the peaks are no different from the program levels. The difference between the highest and lowest signal levels in a typical TV spot is much less (even the quiet moments are high) than you'll find a typical program track (the quiet moments are much lower).

Could also be that the stations are using level-normalizing only on the feed to the OTA transmitter, and not on the feed to the cable company.

With an FM transmitter you want as consistent a modulation signal as possible, since modulation level affects ability to detect the signal, especially in the fringe areas. With consistent modulation you have consistent range. And with consistent range you reach more people and can charge more for your air time. So some sort of normalizing and limiting is used with FM transmitters. No such technical issue exists with cable distribution, since there is no fringe area/distance to worry about - you either have adequate full-quieting signal or you don't.

In the 'Vegas market there are substantial differences not only between each OTA station's network vs local feeds, but between the various stations themselves (we're talkin' OTA here, I still refuse to pay a cable company for TV). As you all say, very annoying. I too say just get a PVR or DVR and zip-squeal through the commercials. Or install a gated expander in your audio chain.

Posted by Sam Graham (Member # 2889) on 07-15-2008, 11:18 PM:

quote: Paul Mayer
Could also be that the stations are using level-normalizing only on the feed to the OTA transmitter, and not on the feed to the cable company.

Exactly. It's common now that cable and satellite providers are getting direct feeds from the stations instead of picking them up over the air, and in the process bypassing the station's audio processing at the transmitter.

So compression that would be going on at the transmission site for your local OTA's isn't necessarily being passed through to your cable company.

Posted by Josh Jones (Member # 447) on 07-16-2008, 06:50 PM:

quote: Sam Graham
Exactly. It's common now that cable and satellite providers are getting direct feeds from the stations instead of picking them up over the air, and in the process bypassing the station's audio processing at the transmitter.

+1 on this.

When I worked for a fox station up here, the fiber feeds to the cable companies were pre-optimod feeds straight out of the router. Often times cable providers dond add any processing so if the news board-op isnt watching what they're doing (always the case) you wind up clipping the front end of the fiber modulators and also the in/out circuitry in the router. we did have control of our audio levels on tape program playback, which was set with bars and tone, but commercials were set when they are encoded into the HDD playback video server. Snoozing operators here to.Network programming also bypassed all of our controls so whatever level they sent wound up on air. I had to fix a spot that went to air with one channel out of phase. In studio monitoring was mono luckily, plus the console metering has 180 degree lights that light up with screwed audio.

Sorry for the rant...

JJ

Posted by Louis Bornwasser (Member # 3063) on 07-16-2008, 07:02 PM:

For years....I had an old CBS Labs Stereo Audimax on the TV feed into my stereo. No level changes there!!! (It wouldn't dare!!)Louis