DVD-Video....are the sound tracks in MP3?

EDS_ · « **on:** 11 Sep 2003, 06:19 pm »

I know this shows how out of the loop I really am.

But I can't seem to find a good explaination for DVD-V's audio content format.

If it's regualr MP3 how come it sound so good and MP3 (even perfect ones) do not?

Is it a hyper-MP3? Or is it something else?

bob82274 · « **Reply #1 on:** 11 Sep 2003, 09:44 pm »

Bubba will correct me if I am wrong here but otherwise I believe it works like this...

DVD-V: It has a Dolby Digital track (AC-3) and sometimes a DTS track for audio. These are codecs that are quite different from MP3 in that they are lossless codecs. This is important because this means that none of the frequency is dropped like in an MP3. They have a compression ratio of 12:1 and 4:1 respectivly. They also allow for more than stereo unlike MP3s.

DVD-A: Still uses PCM just with a higher bitrate and frequency than a CD.

bubba966 · « **Reply #2 on:** 11 Sep 2003, 10:05 pm »

Bob,

You pretty much got it.

Though an AC-3 bitstream can be either 10:1 or 12:1 compression. Superbit DVD's and a few other discs use the 10:1 AC-3 compression scheme.

It should also be noted that AC-3 & DTS bitstreams rely on totally different compression schemes. The AC-3 compression is said to be a much better type of compression than what DTS uses. Which explains why they don't sound tremendously different as you'd assume that a DTS track would sound insanely better than a DD track. But usually the differences are small. And sometimes the DD track sounds better, sometimes the DTS track sounds better.

It's also of note that they're not both mixed the same. DTS likes to run the LFE & Surrounds hotter than Dolby does.

michael w · « **Reply #3 on:** 11 Sep 2003, 11:46 pm »

It should also be noted that DD/DTS *are not* lossless codecs.
Both throw away information to enable the bitstream to fit onto a DVD.

The only lossless audio available on DVD is PCM or MLP on DVD-A.

It's DTS that is claimed to be the better codec due to less aggressive compression and a much higher data transfer rate, typically 768kbps vs. 448kbps for DD.
There is also the rarer full bitrate DTS which blazes along at 1536kbps.

But like most things audio that polarise opinion, it's not the specific technology that matters but it's exceution.

More on DVD audio basics here;

http://www.dvddemystified.com/dvdfaq.html#1.23

cheerio

azryan · « **Reply #4 on:** 12 Sep 2003, 01:47 am »

Michael's right.
Both DD and DTS are called 'lossy'.

MP3 can be all sorts of bit rates and number of channels -though on the net you'll typically see only 2-chan, and usually 96, 128, or 192kb per sec.

DD and DTS are passing 6 channels too remember in those higher bit rates.

Also, someone wrote -"DVD-A: Still uses PCM just with a higher bitrate and frequency than a CD."

MP3, DD, and DTS all get converted to PCM before geting converted to analog. Everything's PCM... except Sony/Phillips DSD, which decided to screw up everthing so they could control music.

EDS_ · « **Reply #5 on:** 12 Sep 2003, 09:48 pm »

Thanks guys.

As ususal I had it all wrong. Somehow I thought the AC-3 and/or DTS were not compression schemes but marketing tools......I thought that whatever AC-3 and DTS were they were compressed into an MP3 file.

Any ideas where I can learn about the copyright protections offered on SACD and DVD-A?

Thanks again.