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In Reply to: RE: DVD audio down mix, original stereo? posted by metalhead on June 22, 2007 at 06:55:35
The stereo down-mixes are fold-downs of the 5.1 signal that are artificialy created by your DVD-A player. The original 50 or so Silverline DVD-A's truly suck - even in 5.1. They got much better with later batches (most of the Abravenel Classical Discs, Dar Williams, etc..)
Sorry to se your first impression of Hi-Rez was Silverline... Try other labels. Search the archives here - there are many other companies that put out quality product. (..and plenty of posts ripping Silverline)
Follow Ups:
No, Downmixes are most definitely NOT created by the players.
Downmixes are created at the MLP Encoding phase, and verified there.
There are no players that automatically downmix 5.1 to stereo in DVD-A - if you play a 5.1 only title in a stereo player, if there is no downmix you will get L & R only. NOT a downmix.
FWIW, it is actually very bad practise to create a 5.1 only title - Sonic throws a warning telling you the title cannot be presented in stereo.
To check if a title is genuine stereo or a downmix, simply press the AUDIO button on the remote. PGC Block authoring is very common for 5.1/stereo compatibility, and is done by creating group 1 as 5.1, then adding a second stereo stream to the same group. Playback can be set to access Group 1 on disc load, and playback will access the stream that best suits your player configuration. A 5.1 player will access the 5.1 stream, and if there is no dedicated access to the stereo PGC the AUDIO button, as in DVD-Video, can always switch the stream.
HowdyI took a test disk with channel identification tracks and played it on my Denon 3930. Guess what? When HDMI was selected to be the pure output, the left front and left rear channels both came out of the analog output to the front left speaker (and not the rear), and similarly for the right channels. This seems pretty unambiguous and in direct contradiction to your statement that "Downmixes are most definitely NOT created by the players."
-Ted
Ted.
To quote directly from the Sonic Manual (AKA MEI DVD-Audio Creator)
SMART CONTENT AND DOWNMIXING
DVD-Audio allows — but does not require — both stereo and multichannel
mixes of the same music to be delivered on one disc. To ensure that a DVDAudio disc will always play back, even when the only available mix is
multichannel but the playback system is two-channel, players must support
the SMART Content system.
SMART allows producers to determine in advance a set of downmix
parameters ("coefficients") defining the relative level, panning and phase
that will be applied to each channel of a multichannel mix if it is combined into stereo. A SMART "downmix" will only be played if a discrete 2-channel mix of a given program has not been included on the disc.
SMART downmix coefficients may be prepared in OneClick DVD (if the
target audio format is MLP) or in DVD-Audio Creator’s Import Audio
application (see Chapter 4, section 4.2.6).
Summed up - if there are no co-efficients encoded into the PPCM or MLP stream, the player will only output Left & Right.
If you are hearing Ls/L and Rs/R at the same time, then the stream includes a downmix coefficient created at authoring.
A straight 5.1 stream cannot be automatically downmixed by the player.
The co-efficients are added in one of 2 places:
1 - By the MLP Lossless encoder, or
2 - By the Sonic IMPORT AUDIO applet that forms a part of the MEI Authoring suite when using RAW/PCM or AIF files instead of MLP.
The players cannot do this, as there are too many variables, and the likelihood of clipping or distortion - especially with modern uber-compressed material - precludes the use of any automatic systems, as correct distortion free playback cannot be guaranteed unless the downmix is verified.
Howdy
Now I see what you were saying, I misunderstood. I thought you were saying that no player would downmix a 5.1 disc (which didn't have a stereo section) for stereo only output. I now see that you were saying that the recipe for any such downmixing is set on the disk, and not presumed by any given player.
-Ted
Ted.
If anyone needs to apologise it is me - I am seriously poor at expressing what is in my head a lot of the time - fingers cannot type fast enough to keep up with the flow!!!
(Hey - I am a sound engineer from the Live industry after all!)
But you are essentially correct - the stereo playback is set on the disc, not in the players.
So, do I need to invest in the stereo CD's as well as the DVD audio to get the true original stereo mix? Yes or No would be sufficient, thanks
sadly, the answer is yes
Not always.
The player cannot create a downmix in itself, and if there is no downmix coefficient set by either the MLP encodist or the original disc producer then the DVD player on it's own will only output just the Left & Right channels.
The only exception is a stereo only player, and again - with very few exceptions (IE unless you have a setup screen for allocating what goes where) you will only get Left & Right channels.
Sonic's DVD-A Creator will warn you at compile if the 5.1 stream cannot be presented in Stereo, but will allow you to author the disc because a common workaround is PGC Blocks.
This is a way of embedding & encoding the stereo stream into the same DVD-A group as the 5.1 stream, and the player will always (by default) play the stream you have it set up for. SO if you have a multichannel player, you'll always get the 5.1 but if you have a stereo player, you'll get the dedicated stereo.
Most discs authored this way also have a way to select the stereo stream from a menu. You can also swap over PGC streams by pressing the AUDIO button on the remote - it will start playback from the beginning of the track again.
If this does not work, you're getting either a SMART or MLP downmix.
If there is no downmix set by the authors, you will just get L & R, and the other channels will be disregarded.
Hello, thanks for your reply, I do have other titles also that aren't silverline but I thought these sounded OK, but I don't have a $1000 SACD player LOL, so Just to confirm what you are saying, I won't get the original stereo mix from downmixing these titles?
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