Audio on DVD AC3 versus PCM etc...

[Psychoprick]

Hi,

I've been looking all over for a good explanation of what AC3 and PCM audio actually are.
By that I mean what is the quality difference.

I know AC3 is very small, but is the quality comparable with PCM?

Maybe someone here can direct me to a good guide.

I'm wondering what kind of audio format I should use.
I have some video where the audio is allready bad so size would be most important.
I have some video where the audio is most important and I want to have the best quality not considering size.

Thanx in advance

[OmegaSupreme]

PCM (pulse code modulation) is uncompressed audio. AC3 is compressed audio. Both have variable levels of quality, but in general (all things being equal) PCM is better. How much better is a matter of opinion. All hollywood movies, with their multi-million dollar sound budgets, use AC3, so it is probably good enough for your production.

[Psychoprick]

Hmmm ok thanx,
this is sufficiant for the momment however I could use more info about it for the future....most links and tutorials I find just talk slightly about DVD-audio and focus on Video.


A folowing question is:
What's the easiest way to get my audio from FCP into AC3?
I know of some decoders but are there any encoders?
Is there a way that FCP can use such an encoder directly?

[OmegaSupreme]

The latest version of FCP comes with compressor 2 which can convert audio to AC3.

[Frobozz]

If the video on a single-layer video DVD is longer than 1 hour, using PCM audio means that your video must be encoded at a lower bit rate than it would if you used AC3 audio. Under 1 hour it doesn't make any difference because the highest spec video bit rate and PCM audio will both fit the disc. Typically people are more concerned with the video quality than the audio quality, so using AC3 audio makes better picture quality possible with over 1-hour videos.

PCM is 2-channel stereo whereas commercial encoders can create 5.1 surround AC-3 audio tracks.

I have some commercial concert video DVDs that have both PCM and AC-3 audio tracks. The PCM tracks sound better. In fact, I think music sounds better in 2-channel stereo than 5.1 anyway.

It depends on what matters most to you. I usually choose AC3 but have also chosen PCM when it is a music program.