Method GroupBox : in this Groupbox you can choose between two methods for processing audio.
If you choose MP3 the audio will be processed and encoded in MP3. The programs used to make this operation are Azid (AC3 to WAV) and then Lame (WAV to MP3), or MPA2WAV (when DVD audio is encoded in MPA format) and then again Lame. Using that method you can amplify channels, it's sometimes necessary.
If you check Original, the sound of the DVD will only demultiplexed (ie separate from VOB Files). You can multiplex AC3 using Nandub, but it's hard to multiplex MPA audio. So check out the type of audio used in the DVD you want to encode (in Test Features : English AC3) . If it's MPA or WAV, you should opt for a MP3 method. If you want to keep AC3 remember that it costs a lot of space (do not do a 1 CD movie with AC3)
You can also check Auto Bitrate. This feature depends on the number of pass :
1 pass movies : check the video size after encoding and calculate the good audio kbps to match te desired size defined in the Megs Edit Box. See Auto Bitrate adjust for more details.
MP3 method GroupBox :
Here you can select the kbps used by Lame. Remember that Azid convert Ac3 to Wav, and Lame Wav to Mp3. So this value will not be used if you use Original method or one pass movie with Auto Bitrate and MP3 method (the kbps will be calculate to match size) . It can also be used in case of size problems. See Auto Bitrate Specs.
You can check Variable bitrate, this provides a better encoding of Mp3, but the final size becomes uncertain. Just know that i apply values that prevent from excedeed size. But it cannot be perfect.
You can keep AC3 files or wav files, it allows you to compress audio you're own way.
Test Features GroupBox :
This is for testing gain amplification. Select the channel you want to test in the ComboBox and push test. The beginning of a chapter should be played. You can change the chapter with the + and - push buttons. Don't forget that the method is checked, so you can compare Ac3dec and Lame decoding.
Auto Bitrate Adjust GroupBox :
These are the parameters for auto Bitrate Adjust for one pass movies (the encoding bitrate of audio
The Auto Bitrate Adjust for one pass movies check the movie size after encoding and adjust audio bitrate to match the desired size defined in the megs edit box. To use auto-bitrate you must check the check box "Use Auto Bitrate" in the method Group Box. For two passes movies, it's the video bitrate that will be changed, the audio will be encode using Mp3 parameters.
Max and Min values are the minimum and maximum bitrate allowed. For exemple if after encoding video there's only enought space to encode audio 16 kbps, and if your minimum audio bitrate is set to 64 kbps, then Aspirator will apply the selected method in case of Exceeded size. Same for too much space.
Excedeed size method tells Aspirator what to do when after video encoding there's not enought or too much space to keep in the bounds defined in the Max and Min Kbps Combo Box. you got different choices, use Max or Min Kbps, use Lame Kbps defined in the Lame GroupBox, Crash System ... only a little crash, skip encoding or for too much size minus 7%. This last feature is useful if you want for exemple a 700 MegaByte movie and there's enougth space to make a good audio encoding in 650 Megabyte, this is checked by the minus 7%.
Demuxer :
This is an audio demultiplexer and encoder. What is this ? If you want to rip audio on a DVD use this feature. If process is checked, the audio will be encode using the method (Azid or Ac3dec) you chose. The Auto Bitrate is of course not used. You can demux all the selected streams (in the audio streams dialog box of Aspirator) or use the chapter to split into various little files the audio of the DVD.