V8 and AC3

LJA wrote on 9/15/2007, 11:29 AM
Has anyone explored the AC3 codecs in V8? There appear to be two: the old one, now labeled Dolby Digital AC-3 Pro, and a new one, Dolby Digital AC-3 Studio. I find that the latter gives me significantly greater dynamic range (loudness) than I was ever able to achieve under the Pro version no matter what custom adjustments I made. The "studio" version renders a bit slower and has a larger RAM footprint than the "pro" version. But the results, even with the default preset, give me much greater control over volume. Other aspects of the sound (frequency, clarity) appear to be about the same or a bit better than before. The "studio" codec may be a bit "brighter". (I am using 5.1 surround.)

Comments

Wolfgang S. wrote on 9/15/2007, 12:27 PM
Yes, there are two Encoder - the Studio Encoder comes with Vegas 8 alone, while the Pro Encoder is delivered by the DVDA (even older Versions).

To adjust the Pro Encoder, some people have suggested to change the dialog normalization to -31 dB, and to change the line mode profile and RF mode profile (in preprocessing) both to none.

However, you cannot customize the AC3 Studio encoder, and this encoder can also not be used if you wish to burn a Blu Ray disc from the timeline.

Desktop: PC AMD 3960X, 24x3,8 Mhz * RTX 3080 Ti (12 GB)* Blackmagic Extreme 4K 12G * QNAP Max8 10 Gb Lan * Resolve Studio 18 * Edius X* Blackmagic Pocket 6K/6K Pro, EVA1, FS7

Laptop: ProArt Studiobook 16 OLED * internal HDR preview * i9 12900H with i-GPU Iris XE * 32 GB Ram) * Geforce RTX 3070 TI 8GB * internal HDR preview on the laptop monitor * Blackmagic Ultrastudio 4K mini

HDR monitor: ProArt Monitor PA32 UCG-K 1600 nits, Atomos Sumo

Others: Edius NX (Canopus NX)-card in an old XP-System. Edius 4.6 and other systems

TheHappyFriar wrote on 9/15/2007, 2:21 PM
Yes, there are two Encoder - the Studio Encoder comes with Vegas 8 alone, while the Pro Encoder is delivered by the DVDA (even older Versions).

That doesn't make much sense... before vegas 7 included DVDA you needed to purchase DVDA or the AC3 encoder to get any AC3 rendering. Why would Sony include a free, limited (can't use custom options with the studio plugin) when you are required to have the better one because you have to buy vegas 8 with dvda 4.5?

not saying you're wrong it's just strange that's how it works out.
LJA wrote on 9/15/2007, 2:28 PM
It is true that the "pro" version is customizable and the "studio" version is not. But making all the adjustments suggested in this forum to the "pro" version has never allowed my to get full dynamic range AC3 recordings. It always appeared that some AGC was being applied. With the "studio" version, using the default or the "5.1 no AGC" templates, I have attained the volume ranges (for special audio effects) that I wanted. The "studio" version works fine with HD DVD (the Toshiba HDA2 player). I haven't tried it with DVDA and other players.
TheHappyFriar wrote on 9/15/2007, 4:38 PM
I only have stereo & default templates, no 5.1 templates for them.
riredale wrote on 9/15/2007, 8:23 PM
I've never noticed any dynamic range issues with the AC3 encoder from V7 to V3. Not saying it couldn't happen, but in encode/decode cycle\ tests I've done where one compares the original with the reconstructed clip on the same timeline (with one 180 degrees out of phase) they have cancelled each other out pretty well.
DJPadre wrote on 9/15/2007, 11:38 PM
"That doesn't make much sense... before vegas 7 included DVDA you needed to purchase DVDA or the AC3 encoder to get any AC3 rendering. Why would Sony include a free, limited (can't use custom options with the studio plugin) when you are required to have the better one because you have to buy vegas 8 with dvda 4.5?

not saying you're wrong it's just strange that's how it works out."

Prolly coz teh Studio version is for AVCHD embedded AC3 output for BD, while the Pro is an independant file
peteros wrote on 9/16/2007, 2:49 AM
My experience is that setting dialog. norm. to -31 dB as well as "none" to the line, RF and RF overmodulation profiles (in preprocessing) can be quite crucial.
DJPadre wrote on 9/16/2007, 4:38 AM
it is.. which is why i made a post about it and decided not to use AVCHD from Vegas for HD output.. among other things..
(search layouts as this was another issue.. )

Until a professional encoder allows me to manipulate my output to MY liking will i use it. As it stands, i now have everything calibrated for DD 5.1 output@448kbps with a -31 ratio.
Without these settings all my gear is out of calibration during edit..
LJA wrote on 9/16/2007, 5:07 AM
Are your project properties set to 5.1 audio?
DJPadre wrote on 9/16/2007, 6:41 AM
who r u asking?
LJA wrote on 9/16/2007, 8:42 AM
"I only have stereo & default templates, no 5.1 templates for them."

"Are your project properties set to 5.1 audio?"

I was asking ""TheHappyFriar".
Wolfgang S. wrote on 9/16/2007, 9:56 AM
> That doesn't make much sense...

Maybe it lookes like that - but maybe you will see, that Vegas 8 OEM versions may take place - just a guess from my side. Maybe is that again bundled with Camcorders - as we had that for Vegas 7. And there no DVDA was included.

Desktop: PC AMD 3960X, 24x3,8 Mhz * RTX 3080 Ti (12 GB)* Blackmagic Extreme 4K 12G * QNAP Max8 10 Gb Lan * Resolve Studio 18 * Edius X* Blackmagic Pocket 6K/6K Pro, EVA1, FS7

Laptop: ProArt Studiobook 16 OLED * internal HDR preview * i9 12900H with i-GPU Iris XE * 32 GB Ram) * Geforce RTX 3070 TI 8GB * internal HDR preview on the laptop monitor * Blackmagic Ultrastudio 4K mini

HDR monitor: ProArt Monitor PA32 UCG-K 1600 nits, Atomos Sumo

Others: Edius NX (Canopus NX)-card in an old XP-System. Edius 4.6 and other systems

TheHappyFriar wrote on 9/16/2007, 10:43 AM
Are your project properties set to 5.1 audio?

I wasn't. I don't remember ever needed vegas 6 to be in 5.1 to have the ac3 5.1 option showing but I guess I did. I've been using the batch render for so long I must of forgotten!

Thank!
LJA wrote on 9/16/2007, 11:24 AM
After reading all that has been contributed here, I am still puzzled. Here are some quantitative results: Documentation of the peaks, and an image of the peaks as displayed in Vegas 8.

The Vegas tracks in the "AC3Peaks.png" are

1-4 Vegas 7
5-8 Vegas 8 Pro (same template as used in Vegas 7)
9-12 Vegas 8 Studio ("5.1 Surround DVD" template)

As you can see, there is substantial difference between the three sets. For the purposes of the impact I was after, the last one "sounds" best. But perhaps I am wrong to attribute this to "dynamic range". Any insight any of you can provide will be helpful.

Thanks,

Larry
jbolley wrote on 1/21/2008, 10:53 AM
As someone stated the studio template has auto gain (like most consumer camcorders.) Pro gives you the option of turning off AGC but (if memory serves) AGC is still on by default. A poor choice in my opinion.

Jesse
DJPadre wrote on 1/21/2008, 1:38 PM
That doesn't make much sense... before vegas 7 included DVDA you needed to purchase DVDA or the AC3 encoder to get any AC3 rendering. Why would Sony include a free, limited (can't use custom options with the studio plugin) when you are required to have the better one because you have to buy vegas 8 with dvda 4.5?

This is becuase sony now include AVCHD rendering with embeded DD 5.1 stream. This means the AC3 is rendered and muxed within vegas as it writes the ISO
I have no idea qhy they went this way, as IMO its a waste of R&D
IF they were going this way, i woudl expect it to offer DD True HD, in turn, the muxed AC3 would utilise the bitrates set within the video to set the audio encode.
THis mayhappen in teh future though, but i honestly doubt it... in any case, this is how the trueHD encoders work (by reading the video bitrate and matching the audio to it)

"It always appeared that some AGC was being applied. "
This is dynamic range compression. Do not ever forget that a 448kbps DD stream runs the full 20khz bandwidth.
This compression adn pro logic Metatdata is purely there to allow a wider range of sound to be mixed within your final output, and retain an clear mix, irrespectvof gain levels.
Just as important as this, it allows a proper MIX DOWN into a stereo stream.
In turn the output is encoded with metadata to which the DVD player reads and sets output gain based on said data. With this your 5.1 mix can tell the dvd player to "drop -3 db across each channel if im running in stereo mode"


As for the Pro version having an auto gain configuration, this is incorrect.
the pro version is strictly compliant with teh standards pout forward by Dolby labs Inc. believe, me, i analysed this when i submitted my work for licensing.
In any case, do not forget that most distribution studios do in fact run these profiles so as to not have any issues with compatibility during playback. If you want your piece to sound good in any and pretty much all sound systems, youd use teh defaults and jsut tweak your dialogue normalisation.
For may studio's they have a seperate diauge crecording which is preprocesed before entering the mix, the soundtrack is then built around that, so you do not notice the differnce in freq response and freq phasing.
In any case, what we do is usually an on cam dialogue recording with a simple background track.
to make a dolby mix work for your piece, one must understnad the fundamentals of EQ and compression (not DR or physical file size, but actual audio compression processing) be it for dialogue, LFE, or backing track.

In the end, i find the Studio AC3 encoder to fail dysmally in teh sense of the fact that its suppsed to enhance our listening pleasure considering its predominately used to encode the audio which is playing back as we watch a HD stream...
As it stands, I feel V8 shoud have the option of importing a prerendered ac3 stream (as one track is fine) then when u select avchd output, it will mux that original ac3 stream with your video, as opposed to trying to process video and ac3 studio audio at the same time.

The compromise is just too great IMO and alot of control for the engineer is lost .

Yes its workable and usable, but without proper specifications of or for the output stream, one cannot have this encode licensed and approved for distribution, let alone used in a way to attain or retain any licensing through Dolby Labs
DJPadre wrote on 1/21/2008, 1:42 PM
pls excuse the typos..

its 830am here and ive been up for 44 hours