Geekzone: technology news, blogs, forums
Guest
Welcome Guest.
You haven't logged in yet. If you don't have an account you can register now.




91 posts

Master Geek
+1 received by user: 3


Topic # 21340 23-Apr-2008 14:48
Send private message

[This was a Geekzone blog entry that didn't get much response, so I'm re-posting here. Might also have some relevance to this HD/.ac3 thread: http://www.geekzone.co.nz/forums.asp?ForumId=83&topicid=21288 ]

For years now on analogue and cable free-to-air TV I've been hearing a dodgy audio artifact on broadcast US TV shows - the likes of Six Feet Under or The Sopranos. It's most noticeable on music featuring sustained solo notes on violins or flutes and is best described as a regular (1 or 2 Hz-ish) momentary jump, bump or gap in the audio. To my old-skool ears it sounds as if someone stopped a 1/4" takeup spool and then let go, bouncing the tape as it comes to rest.

I think I've figured out what it is, from watching Battlestar Galactica Season 3 on PAL DVD. There's an option to choose a 5.1 or stereo soundtrack on these discs. The stereo is sped-up from the original 24fps to 25fps, but pitch-corrected back down. The 5.1 is sped up *and* pitched up from 24 to 25 - just like speeding up an analogue tape.

The artifact I described is exactly what I hear on the stereo DVD soundtrack, and is unbearably bad, especially on the BSG theme tune - that plaintive solo wind instrument and female voice.

Obviously it's a rough-and-ready realtime effect of pitch-correction and speed-adjustment of the soundtrack. It drives me nuts BECAUSE IT'S SOOOOOO BAD AND NO-ONE COMPLAINS.

Well, until now, obviously.

Does anyone know what I mean and/or can shed light?

Cheers,
Tom


Create new topic
41 posts

Geek


  Reply # 126207 24-Apr-2008 19:47
Send private message

You're probably right. PAL encodes of 24fps material run at an artificially faster framerate which raises the pitch of the audio and increases the tempo of the music, among other things. You can apply pitch correction to fix one aspect of it, but that won't fix the speedup.

In your case, it sounds like they applied pitch correction to the DVD DD2.0 track but not the DD5.1 track. Who knows why they might do that. I do know that 2.0 and 5.1 tracks are usually prepared and mixed separately so perhaps they came from different sources for the BSG DVD authors to use.

I remember reading a while back that pitch correction was applied to some of the LOTR DVDs (there's been so many releases of that I can't remember which exactly) much to the widespread disgust of those with a keen ear who could hear the artifacts in the music (particularly the long vocals). You would think that with the budget that movie would have had for DVD release that they would have carefully supervised the pitch correction during the authoring. Despite that the artifacts are still there.

I don't know how it's done in the TV broadcast world -- ie. whether it's done in realtime during transmission, prepared in advance, or not done at all.

Seems to me that there's no easy answer since uncorrected audio has a noticably higher pitch, but ptich 'corrected' audio has artifacts that can be quite severe if done with bad software or by someone who doesn't really know what they're doing. If I were to choose I'd probably go with uncorrected pitch since unless I've heard/seen the broadcast or movie in its original timing I'm probably not likely to even notice. If all we hear and see in NZ is PAL TV and buy only PAL DVDs, most of us probably never hear or see the shows at their 'correct' speed and have no frame of reference to see the difference.

From a purist point of view though, it's good to know most 24p blu-ray discs shouldn't have this problem and with the lossless audio tracks included on many releases, what you're getting is not far off the original master mixes used by the studios -- no speedup, no pitch correction, and no loss of fidelity because of compression.

Create new topic



Twitter »

Follow us to receive Twitter updates when new discussions are posted in our forums:



Follow us to receive Twitter updates when news items and blogs are posted in our frontpage:



Follow us to receive Twitter updates when tech item prices are listed in our price comparison site:





News »

Intel introduces new 8th Generation processors
Posted 21-Aug-2017 19:02


Trend Micro launches Home Network Security
Posted 21-Aug-2017 18:38


Avondale College students at top of Microsoft Office Specialist World Championship
Posted 21-Aug-2017 14:11


Garmin introduces inReach SE+ and inReach Explorer+
Posted 21-Aug-2017 14:05


Public Wi-Fi plus cloud file sharing
Posted 18-Aug-2017 11:20


D-Link NZ launches professional Wireless AC Wave 2 Access Point for businesses
Posted 17-Aug-2017 19:25


Garmin introduces the Rino 700 five-watt two-way handheld radio
Posted 17-Aug-2017 19:04


Garmin announces the Foretrex 601 and Foretrex 701 Ballistic Edition for outdoor and tactical use
Posted 17-Aug-2017 19:02


Brightstar announces new distribution partnership with Samsung Knox platform in Australia
Posted 17-Aug-2017 17:07


Free gig-enabled WiFi network extends across Dunedin
Posted 17-Aug-2017 17:04


Samsung expands with connect Gear S3 Frontier
Posted 17-Aug-2017 15:55


Fact-checking Southern Cross Next cable is fastest to USA
Posted 17-Aug-2017 13:57


Thurrott says Microsoft Surface is dead last for reliability
Posted 16-Aug-2017 15:19


LibreOffice 5.4 works better with Microsoft Office files
Posted 16-Aug-2017 13:32


Certus launches Cognition
Posted 14-Aug-2017 09:31



Geekzone Live »

Try automatic live updates from Geekzone directly in your browser, without refreshing the page, with Geekzone Live now.



Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly to your computer or smartphone by using a feed reader.

Alternatively, you can receive a daily email with Geekzone updates.