The other day I put on the excellent Warner Bros Blu-ray title, An American in Paris, and noticed something odd: the music was coming out of the front left and right speakers. I already know that this disc has seven audio tracks, every single one of which is encoded in Dolby Digital 1/0.0 @ 192kbps. That is, the sound was supposed to come out of the centre channel.
So I started fiddling with the settings on my receiver, the fine Yamaha RX-V3900. Whether I had it set to ‘Surround Decode’, ‘Straight’ or even ‘Pure Direct’, it delivered the sound in two channel stereo format. There was no way to get the sound to come out of the centre channel speaker.
Note: the signal information displays on the receiver clearly indicated that it knew that the incoming audio format was 1/0.0. It made no difference whether the digital bitstream was delivered via HDMI or optical digital audio.
Mono sound delivered as 2/0.0, by contrast, can be made to come out of the centre speaker — which is how one would have heard it at the cinema back in 1951 — simply by engaging one of the Dolby Pro Logic modes.
I raised this with the fine folk at Yamaha Music Australia, who in turn raised it with head office in Japan. They responded (I’ve tidied the grammar a little for readability):
Regarding with your inquiry about Dolby Digital 1.0.When playing back Dolby Digital 1.0 (Centre channel only, no LFE channel) on the RX-V3900, audio is output from L/R speakers. This is specification, and also applies to the Vx65 series receivers.
>Is there any way to listen to audio output from centre channel only with Dolby 1.0?
One of reasons is that Japanese satellite TV uses Dolby Digital 1.0, Dolby Digital 2.0 or 5.1ch periodically in programs with commercial breaks. In such cases sound always move L/R to Center. It is unnatural sound output. Otherwise, recording Dolby Digital 1.0 (Centre channel only) software is rare.
In short: this was a deliberate design decision to deal with a problem with Japanese TV.
Since I raised this, I have checked the performance of a Rotel home theatre processor on this front, and it correctly delivers Dolby 1/0.0 to the centre channel, and only to the centre channel.
I told Yamaha I’d mention this here because it is an issue that should be addressed. After all, its receivers have a ‘Pure Direct’ mode which switches off the front display on the receiver and (optionally in some models) the video circuitry, on the dubious theory that these may in some way interfere with the sound. A far bigger impact on the sound comes from turning one speaker’s sound into two. I could go into details, but the most obvious one is where a group of people are listening. With 2.0, an off-centre listener will have the sound dragged towards the speaker closer to him or here, and introduce comb-pattern frequency response anomalies due to the different path-lengths causing frequency-dependent constructive and destructive interference.
I would also argue that Dolby Digital 1.0 is not rare, although it is not extremely common. However the quality of the titles on which it appears is very important. The two lists that follow show all the titles in my collection which have their primary audio in Dolby Digital 1/0.0 format. There are 36 discs listed. Of those, 19 — more than half — appear in the Internet Movie Database Top 250 Movies list.
- An American in Paris – 1951
- Bonnie and Clyde – 1967
- Casablanca – 1942
- Cool Hand Luke – 1967
- Dog Day Afternoon – 1975
- The Omega Man – 1971
- Rio Bravo – 1959
- The Searchers – 1956
- The Adventures of Robin Hood – 1938
- All the President’s Men – 1976
- Arsenic and Old Lace – 1944
- Being There – 1979
- The Big Sleep – 1946
- The Blob – 1958
- Citizen Kane (Two-Disc Special Edition) – 1941
- A Clockwork Orange – 1971
- Destination Moon – 1950
- Freaks – 1932
- Friday the 13th – 1980
- Goodbye Mr Chips – 1939
- It’s A Wonderful Life – 1946
- Key Largo – 1948
- King Kong – 1933
- The Maltese Falcon – 1941
- The Night of the Hunter – 1955
- The Philadelphia Story – 1940
- Psycho – 1960
- The Public Enemy – 1931
- Singin’ in the Rain – 1952
- Soylent Green – 1973
- A Streetcar Named Desire – 1951
- Them! – 1954
- To Kill A Mockingbird – 1962
- The Treasure of the Sierra Madre – 1948
- White Heat – 1949
- Who’s Afraid of Virginia Woolf? – 1966
Clearly, I shall henceforth have to include this audio format in my suite of tests for home theatre receivers.
UPDATE (Thursday, 13 August 2009, 11:39 pm): Another 1.0 BD: The Getaway – 1972.