[Help] identifying encoded but unflagged matrixed surround mixes (2.0/4.0) - (5.1/6.1)

[kiyoakiwah]

i see that there's a lot of DVDs/BDs that have matrixed 2.0/5.1 tracks but they aren't flagged so they just show up as standard 2.0/5.1... which shouldn't be the case and it's annoying
is there any way to identify them if they're not labelled on the product? if you have knowledge about the matrix encode you can just force it on the decoder.

this seems to extend to D-VHS AC3 tracks too... probably not the MP2/MP1 stereo tracks though.
i've even seen mentions of LDs that only show stereo, but are actually 2.0 surround sound.
PCM, DTS/DTS-HD MA, AAC-LC and maybe even E-AC3 seem to do this as well. god knows what!

doesn't seem to be a problem for 5 track Cinema DTS as it's indicated in the serial number (65XXX)

[zoidberg]

I guess the simplest way to find out is to force the decoding, it will be pretty obvious if a 2.0 mix is a true Lt-Rt mix as you will either get distinct content in the L-C-R-S channels or you won't (likewise a Surround EX/ES title with it's surround back channel). Usually a film will have either a Dolby Stereo or Ultra Stereo credit during the end credit roll as well.

You will find that with a lot of recent releases, the 2.0 is actually a mix-down of the 5.1 mix. Occasionally it will be the original Lt-Rt but mostly they are mixdowns for soundbars and such.

[kiyoakiwah]

You will find that with a lot of recent releases, the 2.0 is actually a mix-down of the 5.1 mix. Occasionally it will be the original Lt-Rt but mostly they are mixdowns for soundbars and such.

really not a fan of that practice... is there a simple way to detect surround -> stereo downmixes? i would rather listen to the intended surround mix then, but i prefer stereo/mono as those are the originals for most of the films i watch and i've grown accustomed (they are really nice on a good pair of headphones) i even see mentions of stereo or surround -> mono downmixes, i assume those are far more difficult to detect?

sometimes sound engineers mess up and when creating a dolby sorround mix they end up with dual mono. i think i've encoutered this on a streaming release of a 2002s japanese film. the dvd was 2.0 surround, it's somewhat funny to see. quadro was really popular over there - i assume partially because of laserdiscs

also thank you on the explanation, i guess it is pretty obvious when you're listening for it. there's also usually enough information to detect it without playback!