Film-Tech Forum ARCHIVE: DD 5.1 bitrate on DSS Broadcasts

This is topic DD 5.1 bitrate on DSS Broadcasts in forum Film-Yak at Film-Tech Forum ARCHIVE.

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Posted by Bobby Henderson (Member # 840) on 02-23-2003, 11:12 PM:

Does anyone know the bitrates used for Dolby Digital on DSS broadcasts?

I have a Dish Network Dish500 system, and have the receiver set with DD output enabled for pay per view movies and DD 5.1 reception on many HBO broadcasts. Watching anything from "The Sopranos" to movies like "Ali" (which is playing as I write this) in DD 5.1 is nice. However, I notice varying levels of audio quality in DD 5.1 between HDTV broadcasts, standard definition broadcasts and pay per view broadcasts. I suspect varying bitrate levels are being used.

I first noticed this up in Colorado watching HBO HD on my father's expensive setup. The DD 5.1 audio on HBO HD seemed right in line with the audio quality one would hear on DVD. Flip over a couple channels to a standard definition station showing something in DD 5.1 and the quality seemed to drop.

I've seen the same difference between watching something on DVD and then seeing the same movie on standard-def HBO with a DD 5.1 broadcast. The sound is still decent, but kind of weak. The channel separation doesn't seem quite as good and the audio doesn't have the same "oomph" to it. It makes me wonder if the DD 5.1 bitrate is dropped down from a normal 448kb/s or 384kb/s level down to rates like 320kb/s, 256kb/s or even a paltry 192kb/s.

Does anyone know for sure?

Posted by Justin McLeod (Member # 1329) on 02-23-2003, 11:27 PM:

This is off topic for a reply, but when is HDTV going to start broadcasting with DTS?

Posted by Bobby Henderson (Member # 840) on 02-24-2003, 01:47 AM:

To respond to the OT question, I wouldn't hold my breath for over-the-air HD broadcasts with DTS. The 6MHz spectrum is only going to hold so much data.

However, DTS in digital cable and broadband HD delivery would be a possibility. DTS has their own solution available. But right now I think DTS is fighting on other fronts, such as being included in the D-VHS "D-Theater" format and HD-DVD. Ultimately, DTS is always fighting against the "Dolby Digital is just fine" attitude.

HDTV has larger, more looming issues such as Hollywood studios and their lawyers threatening to derail the entire HD format with their 5C DTCP copy protection initiative (which could make over 2 million digital TVs sold to this date functionally obsolete and only able to receive an NTSC 480p signal).

To get back on the topic of this post regarding Dolby Digital 5.1 on DSS broadcasts, a good analogy for the quality difference I am hearing would be low bitrate MP3 music files versus a high bitrate MP3. I can't put my finger on it, but the sound quality seems a little "blurry" (if that could be used as a good description). It doesn't quite have the same pop as what I hear on DVD.

Posted by Mark Lensenmayer (Member # 134) on 02-24-2003, 07:42 AM:

Another oddity with Dolby Digital 5.1...I'm picking it up on HBO, SHOWTIME and STARZ via digital cable. I have noticed they shut off the 5-channel bitstream during the credits. It drops back to 2-channel at that point. Don't see any special reason why, unless its another anti-piracy ploy.

Posted by Bobby Henderson (Member # 840) on 02-24-2003, 10:50 AM:

That's weird. The DD 5.1 bitstream keeps going on my HBO shows right until the credits finish and the HBO next movie promo card comes up.

Posted by Joe Redifer (Member # 3) on 02-24-2003, 11:55 AM:

Since 128kbps is way plenty good enough for CD quality MP3s (and CD quality CANNOT EVER be improved upon) I think 128kbps should be plenty fine for 5.1 Dolby Digital. Oh hell yeah! [Smile]

Actually I encode all of my DVDs in 5.1 and 448kbps. Sorry for the slightly off topic post. I'll moderate it later.