AVIA & DVE actual dBFS Levels

[MACCA350]

I thought this may be of interest.

I now have both DVE(HD DVD/DVD combo) and AVIA. So I was able to load them both into Sound Forge and check the dBFS levels. I did some more reading on Sound Forge and found a more precise way to check the dBFS levels using the Normalization feature where I can select a section to process and Sound Forge will tell me the 'Average RMS Level' in dBFS.

I used an Audio Extractor program to digitally transfer the DD 5.1 channel audio to 6 separate wave files at 24bit/48kHz and discarded the unneeded channels(this ensures no mixing has taken place).
The only thing I don't know is if the Dolby Dialog Normalization has any effect on this process, if it does then these figures may be after the offset is applied(but I can't confirm that)
FYI, my 3805 shows:
AVIA Dialog Norm OFFSET -4dB
DVE Dialog Norm OFFSET 0dB

I then loaded them into Sound Forge and used the Normalization function to read the RMS dBFS level of the selection(as seen in the timestamps)


AVIA
Left channel.....-23.6 dBFS (1-2sec) 1 second long
.......................-23.2 dBFS (1-59sec) 58 seconds long

Left ch HF........-23.6 dBFS (1-2sec) 1 second long
............LF........-25.5 dBFS (4-5sec) 1 second long

DVE
Left channel.....-36.4 dBFS (1-2sec) 1 second long
.......................-36.0 dBFS (1-9sec) 8 seconds long

LFE channel.....-32.8 dBFS (1-2sec) 1 second long
.......................-30.3 dBFS (8-9sec) 1 second long
.......................-30.9 dBFS (1-9sec) 8 seconds long

Just for reference,
Avia says the Main Channel tests should read 85db(C) on a SPL meter(the redirected sub tests are meant to read at equal levels and can be checked with level anywhere above 70dB),
DVE menu states that the 5.1 Multichannel levels are -30dBFS

cheers
Mods, please let me know if you would like anything changed in this post

 

[MDS]

I guess we could say close enough since AVIA should be -20 dB and DVE should be -30 dB.

You have different selection lengths for each channel. After extraction, how long was the sound for each channel? You'd have to calculate the RMS level over equal length selections otherwise the result will be misleading. If you select only a few seconds of a long song and run statistics the average level for that selection could be higher or lower than the averge for the whole song.

 

[MACCA350]

I guess we could say close enough since AVIA should be -20 dB and DVE should be -30 dB.

You have different selection lengths for each channel. After extraction, how long was the sound for each channel? You'd have to calculate the RMS level over equal length selections otherwise the result will be misleading. If you select only a few seconds of a long song and run statistics the average level for that selection could be higher or lower than the average for the whole song.

Yes, thats why I used a 1 second sample for all the tests but I also added a longer sample for a couple of them, where I could, to show variations. I'll add the sample length.

cheers

 

[MACCA350]

A couple of things I found interesting.

If The extractor is applying the Dolby Dialog Norm offset during the decoding process this would mean that the AVIA tones should read -24dBFS in the above tests. Again I don't know if this is happening in the decoding process, but it would explain the 3-5dB drop in the signal.

One slight concern on DVE is the 3-6dB difference between the Left and LFE levels. This would mean that you'd have to calibrate the:
Left channel to 69dB(c)
LFE channel to 82-85dB(c)

Oh yeah that DVE LFE test actually increases in level from the start to the end(as you can see in the tests it's about a 2.5dB difference)

cheers

 

[MDS]

Well I guess you are fully hooked on Sound Forge and exploring the true details of the audo we love. Welcome to the club.

I don't know the answer to the DialNorm question but I thought it was only applied during processing so it wouldn't come into play if you just rip the track from a disc. As I understand it, DialNorm indicates how far from the 'standard' (THX) level of -31 dBFS is the actual average level of the audio so the processor can boost or attenuate it as necessary to bring it in line with the -31 dB standard.

Good stuff MACCA350. Like I need more 'projects' to investigate for no reason at all other than I am curious, like you.

 

[MACCA350]

Well I guess you are fully hooked on Sound Forge and exploring the true details of the audo we love. Welcome to the club.

I don't know the answer to the DialNorm question but I thought it was only applied during processing so it wouldn't come into play if you just rip the track from a disc. As I understand it, DialNorm indicates how far from the 'standard' (THX) level of -31 dBFS is the actual average level of the audio so the processor can boost or attenuate it as necessary to bring it in line with the -31 dB standard.

Good stuff MACCA350. Like I need more 'projects' to investigate for no reason at all other than I am curious, like you.

Yeah....it could be called a curse

Considering the 'extractor' will need to decode the raw DD stream to be able to convert it to a .wav file its quite possible that the DialNorm is applied in the decoding process.

BTW I found out a while ago that the DialNorm feature in the DD decoder will only attenuate and the amount can be between 0dB and -31dB as seen in these whitepapers. I have heard of some receivers(tending to be THX certified ones) that display a DialNorm value in the positive. A fellow checked a few titles on his THX receiver and I found that the difference seems to be 4dB and its as if their receiver is setting 0dB at the actual -4dB point.

In other words:
For DVE, my receiver showed 0dB his showed +4dB
For the THX trailer on the Incredible's, my receiver showed -5dB his showed -1dB

At least thats the only explanation I can think of

cheers

 

[mtrycrafts]

I thought this may be of interest.

I now have both DVE(HD DVD/DVD combo) and AVIA. So I was able to load them both into Sound Forge and check the dBFS levels. I did some more reading on Sound Forge and found a more precise way to check the dBFS levels using the Normalization feature where I can select a section to process and Sound Forge will tell me the 'Average RMS Level' in dBFS.

I used an Audio Extractor program to digitally transfer the DD 5.1 channel audio to 6 separate wave files at 24bit/48kHz and discarded the unneeded channels(this ensures no mixing has taken place).
The only thing I don't know is if the Dolby Dialog Normalization has any effect on this process, if it does then these figures may be after the offset is applied(but I can't confirm that)
FYI, my 3805 shows:
AVIA Dialog Norm OFFSET -4dB
DVE Dialog Norm OFFSET 0dB

I then loaded them into Sound Forge and used the Normalization function to read the RMS dBFS level of the selection(as seen in the timestamps)


AVIA
Left channel.....-23.6 dBFS (1-2sec) 1 second long
.......................-23.2 dBFS (1-59sec) 58 seconds long

Left ch HF........-23.6 dBFS (1-2sec) 1 second long
............LF........-25.5 dBFS (4-5sec) 1 second long

DVE
Left channel.....-36.4 dBFS (1-2sec) 1 second long
.......................-36.0 dBFS (1-9sec) 8 seconds long

LFE channel.....-32.8 dBFS (1-2sec) 1 second long
.......................-30.3 dBFS (8-9sec) 1 second long
.......................-30.9 dBFS (1-9sec) 8 seconds long

Just for reference,
Avia says the Main Channel tests should read 85db(C) on a SPL meter(the redirected sub tests are meant to read at equal levels and can be checked with level anywhere above 70dB),
DVE menu states that the 5.1 Multichannel levels are -30dBFS

cheers
Mods, please let me know if you would like anything changed in this post

Not sure this will help you out on Dialogue Normalization:

http://www.hometheaterhifi.com/volume_7_2/feature-article-dialog-normalization-6-2000.html

Interesting testing and results.