Some info on 5.1 movie theatre sound mixes

This is a good resource for info on 5.1 mixes: http://duc.avid.com/showthread.php?t=87830

Among his links is this “Model DP564 Multichannel Audio Decoder User’s Manual” from Dolby:
Model DP564 Multichannel Audio Decoder User’s Manual

For film work, test noise at reference level should produce an SPL of 85 dBC for each of the main front channels (Left, Center, Right) and 82 dBC for each Surround channel . The lower Surround level is specific to film-style mixing rooms. For television work, test noise at reference level is typically set to produce an SPL ranging from 79 to 82 dBC for each of the main five channels. The lower reference level for television reflects the lower average listening levels preferred by the consumer (typically 70 to 75 dBC)

Often a stereo sound mix for TV uses limiters and compressors and has less dynamics than a theatre mix. This is because it is mixed at a 79 dBC per channel instead of 85 dBC per channel.
A movie theatre mix is also mixed with 20 db of headroom.
A TV mix converted to a 5.1 movie theatre mix will have less dynamics. The best option is to go back to the stems/sources that was used to make the TV mix and mix it again at 85 dBC per channel.
I recommend having all movie theatre mixes done at a professional film mixer that uses the 85 dBC per channel standard.

If you are converting a stereo TV mix to 5.1 mix for DCP use I recommend using Pro tools and a upmixing plugin. You can match the dialogue normalization level, but not the the dynamics of a proper 85 dbC movie theatre mix.

5 Replies to “Some info on 5.1 movie theatre sound mixes”

  1. Hi KE,

    After a long rendering process I managed to build my first DCP for a festival viewing.
    Playing back the DCP on EasyDCP Player+ 1.3.1, I noticed the audio is lagging a bit.
    In the system info box under audio it says: expected latency = 0.125 sec.

    Is this something to worry about for the festival, or is it a short comming of EasyDCP player and will it be sync when played with a Doremi DCP – 2000? If not, does those servers have the ability to adjust sync problems? I KNOW for sure the audio files and video files were sync when added to easyDCP creator.

    Thanks in advance!

    Brenn

  2. Hi,
    If your sound is in sync on the orginal source and you have the same amount of frames on your picture and sound assets or have synced them with offset/duration, your DCP will also be in sync. The doremi and sound cinema system is adjusted for latency to be in sync. It may be that you should have 0 latency. My easydcp player has 0 latency. Maybe a upgrade to version 1.6 or using a different default sound card in your OS will fix it.

  3. Thanks for the info.
    I think the fact EasyDCP player “sees” a latency, it proves to be in the system, and not in the DCP.

  4. From the Fraunhofer Easydcp player manual:
    5.10
    Audio Output Device
    Both easyDCP Player and easyDCP Player+ support multi-channel output. By default the audio output device that supports most channels will be selected. Open the system info dialog (F10) for a list of all detected audio output devices and their IDs. You can manually override which device should be used by editing the settings.ini file in the easyDCP Player application data folder (see 4.6).
    [audio]
    audio_dev_idx=1
    “1” is an example and may have to be replaced by another audio output device number.
    If only a stereo output device is detected but a loaded DCP has surround sound, it will be downmixed to stereo.
    Some devices report a default latency, which is typically not higher than 125 milliseconds. By default, easyDCP Player will compensate for this audio delay. This default delay can be tweaked by editing the settings.ini file and entering a different value between 0 and 1, e g. “0.080” for 80 milliseconds.
    [audio]
    audio_latency_secs=0.080

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