Hi first post here :)

I made the sound, music for a short film (a stereo 48k mix). The film had no dialogue. I noticed though in the screenings (2 film fetsivals) that the stereo image was almost gone. So i am wondering if this is a problem with the format it was delivered (thus stereo) or if there was some encoding-decoding to something different from the festival that messed with the soundtrack.




Hi Greg

Stereo sound like we know from music was never used in cinema. There are lots of article if you search in books or google, I can explain you the main facts: In the past, the first audio format was mono with one speaker in the middle of the screen. This format is still the most important channel if you imagine the situation of a cinema. Wherever you sit in a cinema, you will hear the things from screen 'out' of the screen. So 'stereo' as we know from music is not recommendable in cinemas: it's always focused on hard left or hard right. Imagine if you sit left, you only hear the things from left very present and it's not coming out of the screen. This is weird and irritating, so this format makes no sense in the cinema. Later, if the format extended into multichanels, the centerchanel still is the most important channel from all. The next format was Dolby Stereo with 4 channels: Center, Left, Right And Surround and was used a long time until the digital format brought more and more channels. But the situation always stay's the same: the sound should come out where the action is, and this is from the screen and should be as realistic as possible. I tell this as a 'surround guy' (see https://www.soundeffects.ch/) Surround is great but should never take the action from the screen, except you really want it. Otherwise it's bad. So if you make a soundtrack for the big screen, it's better to mix it Mono or do it in Dolby Stereo than 'Music-Stereo'.

best Guido

  • One thing I recommend being careful of is that 'Dolby Stereo' is slightly misleading. What you mention here is actually an LtRt (Left Total Right Total) phase matrix of 4 channels, while it's general method of encoding, Dolby has it's own proprietary version in box which handles this on a dub stage and this results in what's known as a Dolby SR print, which can be properly unfolded using ProLogic II technology. The Dolby AC3 file format is capable of at least 6 channels of audio, meaning this a 5.1 and a 2.0 or both 'Dolby encoded', one just has more channels than the other. – Stavrosound Sep 24 '12 at 20:42
  • The LtRt process for digital AC3 file formats happens first, and then the file is encoded as an AC#, where the metadata is flagged to look for the 'surround' meta tag - this flag tells the Dolby playback device that it's dealing with an ltRt which needs to be decoded. What you mention as 'Music-Stereo' is an LoRo (Left Only Right Only). So I guess what I'm clarifying is the the Dolby format is the Dolby format is the Dolby format regardless of how you slice it, it's actually whether you mix for an LoRo or an LtRt (prior to hitting the AC3 encoder) which actually makes the difference here. – Stavrosound Sep 24 '12 at 20:45
  • Hi Stravrosound, of course I mean LtRt. And for correct mixing and encoding it's highly recommended to go into a studio. But if the budget does not allow it's probably better to mix in 5.1 without using the rear channels than using stereo. Mono is quite boring but still better than stereo 2.0 format. – Guido Helbling Sep 25 '12 at 11:43

Hi greg!

Most festival/venues i've been to, tend to mess up (stereo) soundtracks. Not sure if this is the case ofcourse. Did you hear phasing issues or was it just monophonic? Where did you mix your short? Most of the time is has to do with the setup (i've seen very old speakers and cheap mixers in the projection room) or the dolby matrix 'compatibility' of your soundtrack. Did you do a soundcheck? I've been doing this everytime and saved the soundtrack multiple times from an unholy monophonic meltdown.

Also try and search a bit more in SSD, this has been discussed before, so there's a lot of information already here.



In my experience in presentation and film festivals, essentially we prologic any stereo content. Stereo in a cinema is bad because the stereo phantom centre will move depending on where you're sitting, so the tradeoff is made so centre information like dialogue is always actually coming from the centre.

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