dvd audio tracks

[fedge]

Now i need a little clarification. Is the audio track on a dvd actually the AC3 track that dvd2avi will rip off the vob files.. OR is it something else. The only reason i ask is because i am thinking there is a marketing lie inherant in the dvd. They are claiming that the audio is better than anything else(witch i believe if it is JUST dvd audio disk.) BUT, a 5.1ac3 audio track for a 2 hour movie is only about 300+mb or so... THIS IS LESS THAN A NORMAL CD!!!... SO, in actuallity the sound would be COMPRESSED audio which is always lesser quality than say a CD or superaudioCD or DVDaudio disk.(compressed similar to a multitrack MP3)

Is this REALLY true or am i mistaken.

[KpeX]

Yes, AC3 is a lossy format. That's no secret. Quality is subjective. Personally I'd rather have a well mastered 5.1 AC3 surround track than a 2 channel wav that's 'theoretically' higher quality. And I've never heard anyone claim DVD AC3 audio is 'better than anything else'. And you're correct, AC3 can be analogous to a multichannel MP3, the bitrate per channel is similar, the difference lies in encoding engine and features like DRC.

Personally I am a little annoyed by CD/DVD analogies. Ripping CDs and DVDs are totally different, ripping a DVD is a transcoding processe, video and audio are both stored in lossy formats. Current technology doesn't have enough storage to make uncompressed video and audio for a full length film practical.

[fedge]

well i use the analogies that the marketing wizards seems to suggest to the public. While not saying that a dvd has better or the same as cd quality, it is apparent that they are claiming that it is in someway. Just the way that they advertise it, "hear a pin drop"... this all just goes to show you that the best thing to do is research something.. and i have. Now i know what the REAL truth is, i tend never to trust advertisements, and approach everything with a grain of skepticism in my teeth. I do agree with you that AC3 tracks at the same bitrate as a similar sized MP3 sound suppior. I have noticed this myself. But ALSO, for the average person, most people could not tell the difference between an AC3 track and a CD (becuase they lack the equipment to do so OR the ability to hear the difference), so really the point is moot. Its just another piece of knowledge i can put in my head....

[Tonio Roffo]

Audio quality is very subjective.

It IS possible to claim AC3 2 channel at a decent bitrate is superiour to linear PCM (which is, when you look at the process, also just a lossy representation of the analog source...!) because it's 48khz and should have more resolution closer to the 20khz signals.

What would be better, a psychoacoustic compressed (lets say 4:1) signal @ 48 khz 20 bit, or linear 16 bit 44khz, if we start from, let's say, a digital 96khz 24bit source..?

It's very hard to tell, don't you think? If it's MP3's compressed from a 16 bit 44khz source, then yes, you lost information. But (I don't know if mp3 supports it...) if you could encode, let's say, a 256 or 384kbit MP3 @ 24 bit from a high quality master.... what would sound best?

Compression is not nescessary more lossy than lower quality PCM