/Commericial DVD Audio Compression

[mjl54]

Hi.

I'm posing a question that, I hope, someone can answer.

Some kind of digital compression is normal for commercially authored DVDs, I'm assuming. I have found that DVDs from feature films, the audio is clipped, especially the low tones. I wonder how much compression is taking place, because I've watched the SAME movies on a broadcast band, and the quality is 100%, but the DVD version is not as good. If the studios as authoring this way to save money, then I don't like it. Some DVDs are out of sync. Now, what I want to know is, does anybody got ideas on that? (I've worked in both film and video, here and there, but I'm not expert on digital compression.)

Mike,

[Cornucopia]

That's a mighty BROAD stroke you're painting there!

Don't know about your experiences (maybe you could give some actual concrete examples?...), but my experience has been quite the reverse.

Both Video & Audio have always been better on DVD than on OTA/Sat/Cable. No clipping, not out-of-sync. Most Hollywood titles are nearly "uncompressed".

***By "Audio Compression, I take from your context that you're referring to audio Dynamic Range compression, not digital bitrate compression...

How are you viewing these? Through an HTPC? Maybe it's playback chain has been compromised.

You're a "self-proclaimed" NON-expert at compression. Well, I don't know if I'd call myself "EXPERT" with all CAPS, but I'm pretty close to it, having done that (Film, Audio, Video, Multimedia) for a living for years.


Assuming you're not just trolling/flame-baiting, I'm curious about these titles you're finding fault with.

Scott

[mjl54]

Hi.
Thanks for your reply. I was watching Game of Thrones at my son's place. At certain frequencies we noticed a buzz such as you get with over-modulation (I think - as I said I'm not an expert, and most of your reply was incomprehensible to me - which just shows how little I know). So maybe the problem is the TV itself, the sound system perhaps, and I don't know the origin of the DVD we were watching (pirated? I don't know).

As for compression, what I think I meant was how audio is compressed (such as when you convert a WAV file to MP3, for instance - at least, I think that's what happens. So there would I guess be some drop in quality, I imagine). So if I'm wrong about this, that's good news. It must be something else. I noticed a similar thing on my own TV (which is old, not a widescreen), when watching a movie I'd previously seen on a movie channel, and the dialog was a little unclear here and there. Could it be that the speakers themselves are inadequate in that they don't have the range of the audio being transmitted?

I may talking a lot of nonsense, so please excuse my lack of knowledge, but I'd appreciate an explanation, if you have one.

Thanks. I used to work in film, so my experience with video is certainly limited to what I learned later from some digital video editing I did a while back.

Mike.

[Noahtuck]

I was watching Game of Thrones at my son's place.

Then you are not watching officially released dvd's as the first season has NOT been released on dvd yet
So that kind of shoots down that....

[mjl54]

Hi Noahtuck. But that doesn't explain the officially released DVD I was watching at home. It was a DVD release of the movie "Defiance." So, barring the obvious, what else could it be?

Thanks for help.

Mike.

[aedipuss]

what are you listening to the audio through? the tv speakers? full THX audio setup?

[jagabo]

I have found that DVDs from feature films, the audio is clipped, especially the low tones.

My guess is you have the bass cranked way up because your speakers are inadequate. That is what's causing the clipping (ie, your amp is clipping).

the dialog was a little unclear here and there.

That may be an incorrect 5.1 downmix to stereo. Or improper speaker setup.

Could it be that the speakers themselves are inadequate

Yes.

Audio on DVDs is usually of very high quality. 224 kbps 2.0 or 448 kbps 5.1 Some DVDs even have uncompressed stereo LPCM.

[edDV]

...
As for compression, what I think I meant was how audio is compressed (such as when you convert a WAV file to MP3, for instance - at least, I think that's what happens. So there would I guess be some drop in quality, I imagine). So if I'm wrong about this, that's good news. It must be something else. I noticed a similar thing on my own TV (which is old, not a widescreen), when watching a movie I'd previously seen on a movie channel, and the dialog was a little unclear here and there. Could it be that the speakers themselves are inadequate in that they don't have the range of the audio being transmitted?
...

Most likely your amp/speaker quality or settings. DVD AC3 is usually very high quality but has high dynamic range. When you set volume for low volume voice, the explosions will cause clipping on cheap amps/speakers. Most amps have volume compression control, some just a "night mode" reduced dynamic range setting.

Take your DVD down to a quality home theater showroom and have them play it on a mid to high end system.