AC3 2.0 on DVD, really mono?

[oscarm]

Old movies released on DVD tend to be recorded in mono but of course it's in ac3 format 2.0 on the DVD.
When i want to encode the audio from AC3 to MP3 i want to make sure that I'm using the right preset.

I know i had some kind of software before that analyzed the audio file and told you if it was mono or stereo.
I have googled quite a bit, but I can't find any relevant information.

Could someone here please enlighten me?

[jagabo]

Why don't you just listen to it? Mono is obvious -- especially with headphones.

[oscarm]

Why don't you just listen to it? Mono is obvious -- especially with headphones.

I don't have any headphones, and it is quite hard to know when it's only dialouge.

[johns0]

Only way to tell is to load up the ac3 in an audio editor and see if the 2 channels are the same all the way through.If its recorded as mono then it will only come through one channel.

[AlanHK]

I don't have any headphones, and it is quite hard to know when it's only dialouge.

Try a modern movie or TV show in stereo, see if you can tell.
If dialogue is recorded stereo, you hear one person distinctly placed on the left, and the other on the right.
If not, it's almost certainly mono.

And you don't even have Walkman style mini earphones? Cost about $1 for cheap ones, useful when working on a PC sound editor.

[edDV]

Stereo was generally introduced to film in the 50's and Dolby was added in the 80's. Some DVD releases of early films added faked stereo. Also, they probably equalized the old "Academy Curve" to something else.
http://www.hometheaterhifi.com/volume_9_2/feature-article-curves-6-2002.html

[oscarm]

Thanks for the answers, what audio editor can you recommend?

[jman98]

Maybe audacity would work well for you an audio editor. It's free.

edDV is right, but do note that his response really applies to American films. And just because some films used stereo in the 1950s, that does not mean that all films did. Cheaper films continued to use mono for years and outside of the US mono sound was the norm in many places. Russia continued using mono sound through the 70s at an absolute minimum and didn't move to stereo until the 80s or maybe even the 90s (I know that in the 90s there was some stereo usage, but I am unsure of the exact start dates for this). Hong Kong films were in mono until the 90s.