Is stereo AC3 exactly the same as MP2

[RabidDog]

Is stereo AC3 exactly the same as MP2? I have just "converted" a 192k ac3 Dolby digital file to mp2( at 192k) and to my surprise its exactly the same size .. down to the last byte. Does this mean that ac3 is really just an extension to the mp2 standard to accommodate surround sound?. Really meaning that conversion of stereo ac3 to mp2 at the same bitrate should be merely a matter of rewriting the header record... and the file extension of course... I will try to get a byte comparison tool to see exactly what the difference are. Or is this just too simple to be true??

[politiken]

Hi

No! - MP2 is just a compressed format whereas AC3 is a compressed format, with SurroundSound and created for use in large theaters (giving you the possibility to hear whispering and bombs exploding at the same time without getting your ears damaged)

Mp2 / Mp1 (.mp2, .mp1) - is the predecessor to Mp3, by today's standard mp2/mp1 compression no longer cuts the mustard (compression wise).

You can read more info here:

http://mornmist.2y.net/~blibbler/tutorial/basic/convertmpeg2.html
https://www.videohelp.com/forum/archive/t176533.html

[turk690]

*.ac3 is not *.mp2. Both are official DVD audio formats. A realistic way of noting filesize differences would be to take a stereo *.wav file, then encode it first to a *.mp2, then same *.wav file to an *.ac3, using the same bitrate. Since these bitrates are fixed both resulting files will have the same, if not very close, filesizes. At high enough bitrates (about 256kb/s), both sound much the same to me. But the chances of getting played back correctly with a random DVD player is higher for *.ac3 than it is for *.mp2. There is one other convenience for *.ac3. Some will have their DVD player's digital outputs connected to their amplifiers that have built-in Dolby digital, DTS, and PCM decoders. Such an amplifier will immediately detect the Dolby digital bitstream, and decode and play it back properly. But a DVD with an *.mp2 track will just produce silence, unless that DVD player is set to "output *.mp2 (or MPEG, etc.) to *.pcm", at which, again the amplifier's decoder, picking up the PCM stream, will play it back so. There is only one receiver I am aware of that will decode and play back an *.mp2 or *.mp3 bitstream natively (without it having to be converted to *.pcm first), and that is by Harman-Kardon (forgot the model). Politiken's links are helpful.

[RabidDog]

yes, they are completely different internally... oh well besweet is useful after all.. even if it has the worst interface in christendom (and other equally vaild religions).