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» Film-Tech Forum ARCHIVE   » Community   » Film-Yak   » DD 5.1 bitrate on DSS Broadcasts

   
Author Topic: DD 5.1 bitrate on DSS Broadcasts
Bobby Henderson
"Ask me about Trajan."

Posts: 10973
From: Lawton, OK, USA
Registered: Apr 2001


 - posted 02-23-2003 11:12 PM      Profile for Bobby Henderson   Email Bobby Henderson   Send New Private Message       Edit/Delete Post 
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?

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Justin McLeod
Film Handler

Posts: 93
From: Oklahoma City, OK, USA
Registered: Jun 2002


 - posted 02-23-2003 11:27 PM      Profile for Justin McLeod   Email Justin McLeod   Send New Private Message       Edit/Delete Post 
This is off topic for a reply, but when is HDTV going to start broadcasting with DTS?

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Bobby Henderson
"Ask me about Trajan."

Posts: 10973
From: Lawton, OK, USA
Registered: Apr 2001


 - posted 02-24-2003 01:47 AM      Profile for Bobby Henderson   Email Bobby Henderson   Send New Private Message       Edit/Delete Post 
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.

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Mark Lensenmayer
Phenomenal Film Handler

Posts: 1605
From: Upper Arlington, OH
Registered: Sep 1999


 - posted 02-24-2003 07:42 AM      Profile for Mark Lensenmayer   Email Mark Lensenmayer   Send New Private Message       Edit/Delete Post 
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.

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Bobby Henderson
"Ask me about Trajan."

Posts: 10973
From: Lawton, OK, USA
Registered: Apr 2001


 - posted 02-24-2003 10:50 AM      Profile for Bobby Henderson   Email Bobby Henderson   Send New Private Message       Edit/Delete Post 
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.

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Joe Redifer
You need a beating today

Posts: 12859
From: Denver, Colorado
Registered: May 99


 - posted 02-24-2003 11:55 AM      Profile for Joe Redifer   Author's Homepage   Email Joe Redifer   Send New Private Message       Edit/Delete Post 
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.

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