Convert dolby digital 2-6ch to WAV 2ch. Can it be done easier?

[PabstBlueRibbon]

Hello,

When I want to convert the audio from a DVD I use the free software DVD2AVI. Like the name suggests it converts VOP-files into AVIs. For video convertion I don't find it relevant, because VirtualDub (including the necessary plugin) can do the job as well and with VirtualDub you can de-interlace, cut out the black borders and improve the image quality.

The reason I use DVD2AVI is because of it's audio convertion. I don't know exactly what dolby digital means. But for example when I watch a documentairy with Sir David Attenborough as narrator ambient- and background sounds and soundtracks will degrease in volume when he starts to speak. If you can explain me how Dolby Digital sound is constructed and what it does compared to a regular LPCM signal I will be very interested.

In DVD2AVI you have 4 options about this:



Dynamic Range Control being set to "Off" is the best for music DVDs, however regularly that will cause clipping because the volume gains too loud. You can prevent clipping by switching the Normalisation-option on. After selected the right settings but before running the operation you have to run a Pre-Scale Decision. (By Dolby Digital and DTS you always have to do that.) In most cases the Pre-Scale Decision will last for quite a short time, though it will give a better audio quality. You can convert the samplerate from 48000 to 44100. By setting the convertion-option to UltraHigh the sound quality is the best and the audio track remains synchronized with the videotrack.

For movies the Dynamic Range Control being set to "Off" causes soundtracks and ambient sounds being too dominant. In the included TXT-file it is said the best option for movies is the DRC being set to "Normal". However personally I always try if the option "Light" is sufficient.

In case of Dolby Surround select the option Dolby Surround Downmix.

Despite the option in the menu File > Process WAV I cannot manage to extract a WAV-file only. To obtain a file of the audio you have to convert the video as well. For that I use the crop-option to make the image size as small as possible and for convertion I select a fast lossless codec. DVD2AVI splits the videotrack and audiotrack in two separate files. After the operation I remove the videotrack.

~~~~~~~~~~~~~~~~~~

I will get a good quality audio-track, however using DVD2AVI only for this makes it quite complicated, because I also need to do the video-editing as well.

What are the options to do this more easily and remain control about the dynamic range?

[pandy]

If i understand correctly your intention is to downmix multichannel audio to stereo - AC-3 (DD) standard provide series downmixing scenarios (downmixing matrices - i.e. coefficients used for channel mixing) which are employed to fulfill this task.
If you are interested in AC-3 (DD) audio standard then probably best is to read standard itself (TS 102 366 or ATSC A52A) https://wiki.multimedia.cx/index.php/A52 .
Some mentioned aspects (dialogue normalization etc) are controlled by additional (to audio) data called metadata (also described by specification) - those metadata guide AC-3 (DD) decoder how to decode and process audio data.

[hello_hello]

The reason I use DVD2AVI is because of it's audio convertion. I don't know exactly what dolby digital means. But for example when I watch a documentairy with Sir David Attenborough as narrator ambient- and background sounds and soundtracks will degrease in volume when he starts to speak. If you can explain me how Dolby Digital sound is constructed and what it does compared to a regular LPCM signal I will be very interested.

The original Dolby ProLogic was stereo audio with surround information encoded in such a way it could be decoded as surround by a ProLogic.
The successor was Dolby Digital (Dolby simply being a company name) where the individual channels are.... individual. In the same way a stereo wave file contains two channels, 5.1ch audio would have six. If you were to convert 5.1ch directly to wave you'd have a six channel wave file.
When extracted on it's own, Dolby Digital has an AC3 extension. It's a lossy compression format, much like MP3.

Background sounds increasing and decreasing in volume between speech is classic "volume pumping". When audio is fairly compressed (the dynamic range is reduced) the difference between the loud bits and the quit bits is reduced, and when the audio changes from loud to quiet to loud to quiet fairly quickly, you can sometimes hear the volume of background sounds going up and down. The more you compress the more noticeable it can be, but if you're playing using your TV and it has a "night mode" option for sound, make sure it's disabled for testing. It might be the cause, or you're getting a double-dose of compression.... when the audio is converted, and again on playback.

For Dolby Digital, there's sometimes dynamic range info included in the audio itself. The information tells a player to adjust the volume up or down to make it less dynamic (it can be enabled in a Dolby receiver and there's settings to control how much the audio is compressed, no doubt much like light, normal and heavy etc). If you convert the audio with it enabled, it's encoded that way. I'd never enable dynamic range compression when encoding myself. I encode it all it's "way too dynamic" glory and squish it on playback (I use my PC, but most TVs have a night mode).

I've never used DVD2AVI, but the help file says:

[Output Method]

[Demux] rips out the specific track (AC3, MPA, DTS)
[Demux All Tracks] rips out all raw streams (AC3, MPA, DTS) inside the program stream.
[Decode] decodes the specific AC3 stream or demux the specific LPCM track to the WAV file.

The demux options should give you the original audio, untouched and unmolested by compression. The decode option might apply your dynamic range settings and/or downmix to stereo. You'd have to test it

[nbarzgar]

What are the options to do this more easily and remain control about the dynamic range?

Hello @PabstBlueRibbon, you may want to refer to the guide section of this site. There are a number of very well-done and easy to follow guides around.
Or have a look at the software section (again...?).

To me the most important questions are:
How much time do you like to invest?
What exactly do you want to achieve?

Because numerous free or commercial apps will do exactly what you ask: convert, keep fine quality video and output almost any kind of audio you like.
Recommended, free:
Handbrake/VidCoder (VidCoder is based on Handbrake encoding engine, but in my experience more stable on Windows; both: more options for individual settings, have to know your stuff - or take time to test it )
StaxRip (highly recommended)
XViD4PSP
XMediaRecode

Or the more detailed and almost completely 'manually' controlled way you started on, short summary only:

• Use DGIndex instead of DVD2AVI, would be an option - to demux audio and video from a DVD.
• Then use BeSweet with BeLight GUI for audio conversion. BeSweet (use BeLight) includes options for dynamic range compression, although few. [Or load your audio into Audacity for controlled compression, actually did another short summary on that here.]
• Use VirtualDub for video editing and conversion as you seem to be doing already.
• Finally, mux audio and video with VirtualDub or mkvtooolnix or Yamb+mp4box to the container of your choice.

If you need guides for the tools mentioned, refer to their entries here in the software section, where in the top right-hand corner it says 'Guides'.
Or use the 'Guides' menu at the top of each page here.

Good luck and all the best.