Dolby A: Difference between revisions

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===Optical track Identification===
===Optical track Identification===
Dolby A is difficult to distinguish from [[Dolby SR]] by sight. Like with [[aspect ratios]] it is best to use multiple sources of information in order to help inform your decision. Such sources include the production year of the print, any identifying labels or text on the leader, or in the credits, country of origin, and production information like whether the film was a Hollywood production or low-budget independent film. Do not blinding trust labels added to the print by other projectionists or even from the distributor!
Dolby A is difficult to distinguish from [[Dolby SR]] by sight. Like with [[aspect ratios]] it is best to use multiple sources of information in order to help inform your decision. Such sources include the production year of the print, any identifying labels or text on the leader, or in the credits, country of origin, and production information like whether the film was a Hollywood production or low-budget independent film. Do not blindly trust labels added to the print by other projectionists or even from the distributor!  


====Production Date====
====Production Date====
*It's safe to say that any film made before 1975 will be a mono print. However there are many films released in mono _after_ 1975, especially foreign titles or films made with smaller budgets.
*It's safe to say that any film made before 1975 will be a [[mono]] print. However there are many films released in mono ''after'' 1975, especially foreign titles or films made with smaller budgets.
**Exceptions: There are some cases where mono films were re-released later on with remastered Dolby tracks, but these usually are fairly well labeled and easy to identify.  
**Exceptions: There are some cases where mono films were re-released later on with remastered Dolby tracks, but these usually are fairly well labeled and easy to identify.
* Many studio films made between 1975 and 1985 will have Dolby A tracks.
* Some (but not all) films made after 1986 will have Dolby SR tracks, though A-type was still in use well into the 90s. 


====Visual Inspection====
====Visual Inspection====
* First, make sure it's not a [[mono]] print with two [[variable area]] tracks. This is very common. Look at the two tracks closely, with mono prints they will be identical. With Dolby A or SR prints the tracks will be the same in some spots and differ in others. Check areas that have music in them, the credits at the end of the film are often a good spot.   
* First, make sure it's not a [[mono]] print with two [[variable area]] tracks. This is very common. Look at the two tracks closely, with mono prints they will be identical. With Dolby A or SR prints the tracks will be the same in some spots and different in others. You may need to check multiple spots along the soundtrack before you encounter one where they are different. Check areas that have music in them, the credits at the end of the film are often a good spot to do so.   
* Many studio films made between 1975 and 1985 will have Dolby A tracks. If the tracks look different at any point, you can rule out mono.
* Some (but not all) films with Dolby A tracks will display the word "Dolby" - or "Dolby Stereo" rather than "Dolby SR" - with the Dolby logo in the end credits. But be careful, just because you see one of these in the credits of the film does not guarantee that it is A Type or SR. Some films were released as both mono and stereo prints, or a film may have been re-mastered and released as SR but was originally mono. Seeing the logo in the credits is just another clue to be used with alongside other sources of information.
* Some (but not all) films made after 1986 will have Dolby SR tracks, though A-type was still in use well into the 90s.
* Some (but not all) films with Dolby SR tracks will display the words "Dolby SR" or "Dolby SR Spectral Recording" with the Dolby logo in the end credits. 
* Some (but not all) films with Dolby A tracks will display the word "Dolby" - or "Dolby Stereo" rather than "Dolby SR" - with the Dolby logo in the end credits. But be careful, just because you see one of these in the credits of the film does not guarantee that it is A Type or SR. Some films were released as both mono and stereo prints, or a film may have been re-mastered and released as SR but was originally mono. Seeing the logo in the credits is just another clue to be used with alongside other sources of information.  
* Some (but not all) films with Dolby A tracks will display the words "Stereo" on the edges of the film [[leader]].
* Some (but not all) films with Dolby A tracks will display the words "Stereo" on the edges of the film [[leader]].
* Some (but not all) films with Dolby SR tracks will display the words "Dolby SR" on the edges of the film [[leader]].


===Auditory Identification===
====Auditory Identification====
If you are still unsure, the best way to identify whether you need to play something as Dolby A or Dolby SR is to run a reel and listen. Stand in the room where the film is being played, close enough that you can hear well. It's harder to do this using a booth monitor. Have someone else switch between A and SR if you cannot do it yourself while in the auditorium. Follow the below tips and it should become fairly obvious what is correct.  
If you cannot be 100% certain by using the information above, the best way to identify whether you need to play something as Dolby A or Dolby SR is just to run a reel and listen. Stand in the room where the film is being played, close enough that you can hear well. It's harder to do this using a booth monitor. Have someone else switch between A and SR if you cannot do it yourself while in the auditorium. Follow the below tips and it should become fairly obvious what is correct.  
* A played as SR: the expander does not match the compressor. It will sound bright, tinny, and sibilant.
* A played as SR: the expander does not match the compressor. It will sound bright, tinny, and sibilant.
* SR played as A: Dolby indended SR to be backwards compatible ("reasonably well"). Though the expander and compressor don't match, so it will not sound very good. It's a little harder to identify than A played as SR. It will sounds dull and flat, because you're not getting the full dynamic range of the recorded track. This likely will be more obvious in scenes with music or a lot of sound, rather than dialogue only.  
* SR played as A: Dolby indended SR to be backwards compatible ("reasonably well"). Though the expander and compressor don't match, so it will not sound very good. It's a little harder to identify than A played as SR. It will sounds dull and flat, because you're not getting the full dynamic range of the recorded track. This likely will be more obvious in scenes with music or a lot of sound, rather than dialogue only.