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Audio Encoding
Although you can save encoding your audio files for last, I prefer to save video encoding for the last step before muxing to MKV (or MP4). In reality it's not really important whether the video or audio is encoded first, and in most people prefer to simply queue all the encoding jobs and run them as a batch.
Source Audio and Profile
You'll need to start by selecting the audio file that was created (demuxed) when your D2V project was created back in Part 1. If you're encoding multiple audio files you'll need to select them one at a time and create an encoding job for each.
Audio Profiles
Like most settings in MeGUI, audio encoding options can be stored in profiles. MeGUI includes profiles for encoding with a variety of tools to encode to AAC, MP2, MP3, AC-3 (Dolby Digital), and even OGG Vorbis. If you select a Profile the associated Codec will be automatically selected for you. If you prever you can select the Codec with no preset (profile) to set options manually in the included settings dialog. Although any of the available audio formats can be used in the MKV container, we'll concentrate on the three that are used most often with AVC video - AAC, MP3, and AC-3.AAC
For AAC encoding select ND AAC for the Codec. This will require that you have the Nero Digital AAC encoder installe,d. Although it's not installed automatically like other audio codecs (for licensing reasons) it's considered by some to be the best AAC encoder available, and is worth the minimal effort to download and install it yourself. You can find instructions in our guide on installing MeGUI.MP3
For MP3 encoding you should select LAME MP3 for the Codec. LAME is an exceptional MP3 encoder that's been commonly used for encoding audio for MPEG-4 ASP (DivX, XviD, 3IVX, etc,...) for many years. While MP3 is still an improvement over Dolby Digital in terms of bitrate, AAC's support for the 3/2 surround used on most DVDs, as well as its improved efficiency (smaller files for comparable quality) make it a better choice in most cases.AC-3
Although keeping the original AC-3 audio from a DVD doesn't require any encoding, selecting FFMPEG for the Codec will allow you to downmix 5 or 5.1 channel surround to stereo, or to a lower bitrate. Other formats like MP2 or DTS can also be converted to AC-3.Nero Digital (ND AAC) Encoder Configuration
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1. Channel Configuration
If you're starting with more than 2 channels, as with most primary audio tracks for DVDs, you'll need to decide whether to keep the original channels or downmix to stereo. Downmixing reduces the bitrate required for high quality encoding, but obviously loses the discrete surround information. If you select downmix multichannel to Dolby Pro Logic or downmix multichannel to Dolby Pro Logic II the stereo mix will use one of Dolby's older matrix formats to encode surround information with only 2 discrete channels.
Upmixing
It's also possible to upmix from 2 channels to 5 to create a surround mix from a stereo signal. This generally isn't a good idea since it increases bitrate and is something any device or software capable of playing surround audio should be able to do for you.
2. Setting Bitrate
It's recommended to encode to a specific average or constant bitrate, rather than relying on Nero Digital's Quality based encoding. For stereo encoding typical bitrates vary from 64kbps (kilobits per second) to 96kbps. Multichannel encoding is typically done between 192kbps and 256kbps. Adaptive Bitrate encoding is generally preferred over Constant Bitrate as it typically produces higher quality at the same output size.
LAME MP3 Encoder Configuration
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1. Channel Configuration
Since LAME output files are limted to 2 channels, multichannel surround sound files must be downmixed. As with the AAC encoder you can encode Dolby matrix surround information in your stereo downmix with the downmix multichannel to Dolby Pro Logic or downmix multichannel to Dolby Pro Logic II option or upmix to 5 channels from a stereo source (not recommended).
2. Setting Bitrate
LAME's VBR setting is actually quality based, rather than targetting a specific bitrate. To set the bitrate you'll want to use ABR with a bitrate of 96kbps to 128kbps being typical for stereo.
FFMPEG AC-3 Encoder Configuration
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1. Channel Configuration
Although AC-3 audio is less efficient in terms of file size compared to quality compared to AAC, it has one major advantage in terms of multichannel surround. Since home theater receivers don't currently include AAC surround decoders, you won't be able to maintain surround information across an older S/PDIF (digital audio) connection. If you need to send surround sound across this type of connection you should stick with AC-3. The AC-3 encoder settings include the same options as AAC with respect to the number of channels.
2. Bitrate
AC-3 uses a few standard bitrates, which are listed in kbps. For 2 channels the standard bitrates are 192kbps and 224kbps. For 5 channels either 384kbps or 448kbps are generally used.
Adding Your Job to the Queue
Once you have the encoding options set the way you want them click the OK button to return to the main MeGUI window. The Enqueue button will create the encoding job and add it to the queue. Repeat this process for all audio tracks you want to keep.
Continued On Page 4Next Page 4 - Video Encoding | |
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