Rogers/HDTMN Issues - Sound Level, DD5.1, OAR

[57]

I've called and e-mailed many times regarding these issues - both Rogers and TMN (Astral). I have finally received a response from Astral - from someone who appears to know what he's talking about. Here is his response to my e-mail regarding the issues in the "subject line"

I want to thank you for your feedback with respect to the audio level problems you have been experiencing on the Rogers HD service with our movies.* I have just monitored a couple of movies myself and have seen the very low audio level you have described.* These movies are being pre-digitized and played back from a video file server.* I believe there is an audio gain mis-adjustment in this digitizing process and I am working to verify the details.* I expect to be able to resolve this problem quickly and hope you will bear with us as we iron out the bugs in the HD service.

From your email it seems that you have a very good appreciation of the technical issues involved.* You are correct that this problem is not caused by the "audio range" setting, but it can be made worse with the wrong setting.* You should know that the "audio range" setting does in fact change the audio level.* In addition to changing the dynamic range profile it also normalizes the audio volume through a Dolby parameter called "dial norm", which is the nominal level of the dialog.* On the stereo output of the set top box, you will lose about 11db in the "normal" setting and about 22db in the "wide" setting, only on the digital channels (this parameter does not affect analog channels).* The audio gain shift in audio range "narrow" was set to nominally match audio levels on analog TV channels (so that you don't get huge volume shifts as you change channels).

I will also be working with our programming department on your other issues concerning DD 5.1 and OAR, for HD movies.* I am the in-house champion for both and the person who brought HD and DD5.1 to our Networks.* We are very proud of the fact that we are one of only two Canadian broadcasters who offer DD5.1 in Eastern Canada, and the only Canadian broadcaster who provides regularly scheduled HD movies.* Introducing these technologies has not come without its problems, and again I appreciate your patience as we work out the bugs.

I will update you further when I have an answer to the audio level problem.

VP Technology
Astral Television Networks Inc.

Here is my response to his e-mail:

Mr. XXXX, thank you for your response. I have the following return comments.

1. I tried changing the audio range on my SA3100HD STB several times and there were no changes to audio levels (using the digital out of the SA3100HD.)

2. When I changed the setting on my receiver to "analogue" from digital I did notice that there was a change. I took out my trusty sound level meter and would estimate the changes at about 3dB for each shift from Narrow to Normal to Wide, not 11dB as you mentioned. 22 dB is a HUGE amount and my dB meter would have no problem detecting such a massive shift, it was closer to 5-6 dB for the full shift from Wide to Narrow.

3. This however, does not solve the problem, as I mentioned earlier, I want to use the digital out, not the analogue out to be able to take advantage of the clearer dolby digital signal and to properly decode DD5.1. I don't want to listen to a digital station in analogue audio. Perhaps this is a problem related to the SA3100HD only (or perhaps only my 3100HD), but a 3dB change is not going to take care of the massive 30db differences I've seen anyway...

The movie that is the "worst" for this audio problem is "The Others". This movie is approximately 30dB (yes that much) lower than the others, in the dialogue. As I mentioned in my original e-mail, it almost seems as though your "digitizer" has missed the entire centre channel material and that the only audio picked up is what is contained in the LF & RF channels.

4. I have one more quick question. How do the movies get to Rogers? Do you send a "signal" or is there actually a "tape" sent to their Head End? You mentioned a video file server, so I would assume that you are sending a signal. Please confirm.

I look forward to hearing back from you regarding all of these issues, since the first issue cannot be solved by changing the audio range as I already mentioned.

Thank you again, 57

I'll keep you "posted".

I'd really appreciate it if anyone could verify the items I discussed in my points 1 and 2 regarding the range only affecting analogue audio and not digital, also perhaps the amount of dB effect. Thanks in advance.

[otown47]

Impressive email 57....

I tried "The Others" last night for a few minutes and found (as with some of the other movies) that the analog sound was low and the digital sound was so low it couldn't be amplified correctly no matter how loud the volume was turned up.

What I don't understand is that this is not a "Channel" sound problem as this ABC HD, but a "Movie" problem.....the Sopranos always has the sound level correct. Therefore his assessment of the problem todate isn't necessarily so.

Its interesting that Astral seems to have taken the lead on this problem...not Rogers...

[57]

Originally Posted by otown47

Impressive email 57....

Its interesting that Astral seems to have taken the lead on this problem...not Rogers...

Astral is taking the lead because the problem comes from their digitizing of the movie on their "video file server", as mentioned in the e-mail. Rogers simply "passes" the signal (or tape), so they are blameless in this (exept for not tracking down the issue earlier, since this has been a problem for many months).

[JohnnyG]

Great stuff!

took out my trusty sound level meter and would estimate the changes at about 3dB for each shift from Narrow to Normal to Wide, not 11dB as you mentioned. 22 dB is a HUGE amount and my dB meter would have no problem detecting such a massive shift, it was closer to 5-6 dB for the full shift from Wide to Narrow.

If I'm not mistaken, 3dB in volume is equivalent to 10dB in power, so you are possibly both correct.

[57]

Originally Posted by JohnnyG

If I'm not mistaken, 3dB in volume is equivalent to 10dB in power, so you are possibly both correct.

If I recall correctly, 3dB corresponds to double the power and 10dB is an order of magnitude more power.

ie 90 dB at 1 Watt (typical speaker) would produce 93dB at 2 Watts and 100 dB at 10 Watts and 110 dB at 100 Watts.

[57]

Here is Astral's response to the points I brought up yesterday. (I got the response first thing this morning after sending it last night). I guess once you're in touch with the "right people" things happen. The "red" are Astral's answers to my questions.

1. I tried changing the audio range on my SA3100HD STB several times and there were no changes to audio levels (using the digital out of the SA3100HD.)

The audio range setting only affects the analog stereo output of the set top.* It is used by the Dolby decoder in the set top to set the audio gain.* With the digital output a compressed Dolby digital signal is sent to your receiver and your receiver does the decode according the factory default (or modified if your receiver lets you get in a play with the Dolby decoding parameters).* You are correct though, with the digital out, the audio range setting will not affect the audio level on your receiver/amp system (again it only affects the analog out of the set top).

2. When I changed the setting on my Yamaha RX-V1 receiver to "analogue" from digital I did notice that there was a change. I took out my trusty sound level meter and would estimate the changes at about 3dB for each shift from Narrow to Normal to Wide, not 11dB as you mentioned. 22 dB is a HUGE amount and my dB meter would have no problem detecting such a massive shift, it was closer to 5-6 dB for the full shift from Wide to Narrow.

I have not done detailed measurements myself.* These numbers come from a Dolby/Scientific Atlanta bulletin.* However, in listening to the changes, in wide mode the audio becomes almost inaudible on most programming, which indicates a pretty large shift.

3. This however, does not solve the problem, as I mentioned earlier, I want to use the digital out, not the analogue out to be able to take advantage of the clearer dolby digital signal and to properly decode DD5.1. I don't want to listen to a digital station in analogue audio. Perhaps this is a problem related to the SA3100HD only (or perhaps only my 3100HD), but a 3dB change is not going to take care of the massive 30db differences I've seen anyway...

The movie that is the "worst" for this audio problem is "The Others". This movie is approximately 30dB (yes that much) lower than the others, in the dialogue. As I mentioned in my original e-mail, it almost seems as though your "digitizer" has missed theentire centre channel material and that the only audio picked up is what is contained in the LF & RF channels.

Just to re-iterate what I was saying yesterday...you are not doing anything wrong (though I strongly recommend you use audio range narrow for any analog output use). The problem is at our end in the digitization process.* We don't have enough audio gain in the system and I will get that fixed.* One of the movies I looked at is "The Others" and I agree that the level is at least 25db lower that it should be.

4. I have one more quick question. How do the movies get to Rogers? Do you send a "signal" or is there actually a "tape" sent to their Head End? You mentioned a video file server, so I would assume that you are sending a signal. Please confirm.

The movies are on a digital video tape format (called D5 if you are aware of professional tape formats).* The video tape is played into an MPEGencoding system for storage on the video file server (this is the digitization process).* I fully expect this problem will be fixed simply by boosting thegain at the output of the video tape deck.* I have the operations people who do this work checking that today.* I will let you know when I think we have it fixed and may ask you to let me know if things have improved.* Again I really appreciate your expert feedback.

[bolmsted]

I'm lost.... so does this mean that there will be DD5.1 sound on the HD TMN and PPV channels soon? Also, who is the other company broadcasting DD5.1?

[57]

Originally Posted by bolmsted

1 I'm lost.... so does this mean that there will be DD5.1 sound on the HD TMN and PPV channels soon?
2. Also, who is the other company broadcasting DD5.1?

1. I hope, at least they know we want it... I'll let you know how he responds to that issue, as indicated in the last big paragraph from him in the first post.

2. HDABC, HDPBS, BEV (HD).

[bolmsted]

I forgot to add OAR presentation of films, instead of butchering and chopping???

[57]

???? OAR is one of the issues on the table...

[otown47]

57, I think the Video File Server is at Rogers....

[57]

Aaaah, you could be right (human says the same). It's just that the "we" in the last sentence below taken from his response makes it sound like Astral, not Rogers....

Originally Posted by Astral

The video tape is played into an MPEGencoding system for storage on the video file server (this is the digitization process).* I fully expect this problem will be fixed simply by boosting thegain at the output of the video tape deck.* I have the operations people who do this work checking that today.* I will let you know when I think we have it fixed and may ask you to let me know if things have improved.

[lpr]

A quick note...

The audio on the DVD of the The Others was also *very* low. Maybe this problem is specific to this movie's audio mix.

Later.

[otown47]

Its strange that the HD PPV movies don't seem to have any sound problems....they come from Astral as well. I wonder if its the same process....sneaker net from Astral to Rogers then loading the material onto the Rogers server. In fact, I wonder if all the Astral products make there way over to Rogers by hand????

[JohnnyG]

According to Sound & Vision's Glossary, a dB is:

"A logarithmic unit expressing the ratio of two powers, currents, voltages, or sound-pressure levels (SPLs). An increase of 10 dB represents a tenfold increase in power, and an increase of 20 dB represents a tenfold increase in voltage. Doubling the power in watts delivered to a speaker raises it's output SPL by about 3dB."

And for sensitivity:
A speaker that is 3 dB more sensitive than another requires only half the amplifier power to deliver the same playback volume.

I'm still confused