AC3 - Codec settings | Tips and Techniques
AC3 is best known for its ability to efficiently compress multi-channel audio (surround sound). It supports up to 6 channels for 5.1 surround sound.
Mode
Specifies whether the audio track is converted or copied.
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Codec
Specifies which audio codec is used for encoding.
Language
Sets the language that the player displays when playing.
Delay(ms)
Sets the delay of the audio stream.
Positive values start the stream later.
Negative values start the stream earlier.
Sample rate
Specifies the sample rate.
The higher the sample rate, the richer the sound. The values are between 32000 and 48000 Hz.
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Bitrate
Sets the bitrate. A higher bit rate improves the sound quality but also increases the size of the file. Values are between 32 and 1152 kbps.
Dialogue Normalization
Indicates how far the average dialogue level of the program is below digital 100% full scale (0 dBFS). This parameter determines a level shift during audio reproduction that sets the average volume of the dialogue to a preset level. The goal is to match volume level between program sources. A value of -31dB will result in no volume level change, relative to the source volume, during audio reproduction. Valid values are whole numbers in the range -31 to -1, with -31 being the default.
Room Type
Describes the equalization used during the final mixing session at the studio or on the dubbing stage. A large room is a dubbing stage with the industry standard X-curve equalization; a small room has flat equalization. This field will not be written to the bitstream if both the "Mixing Level" option and the "Room Type" option have the default values.
Mixing Level
Specifies peak sound pressure level (SPL) in the production environment when the mix was mastered. Valid values are 80 to 111.
Dolby Surround Mode
Specifies whether the stereo signal uses Dolby Surround (Pro Logic). This field will only be written to the bitstream if the audio stream is stereo. Using this option does NOT mean the encoder will actually apply Dolby Surround processing.
A/D Converter Type
Indicates whether the audio has passed through HDCD A/D conversion.
- Standard
- HDCD
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Copyright Bit
Specifies whether a copyright exists for this audio.
Original Bit Stream
Specifies whether this audio is from the original source and not a copy.
Center Mix Level
The amount of gain the decoder should apply to the center channel when downmixing to stereo. This field will only be written to the bitstream if a center channel is present. The value is specified as a scale factor. There are 3 valid values:
Lt/Rt Center Mix Level
The amount of gain the decoder should apply to the center channel when downmixing to stereo in Lt/Rt mode.
Lo/Ro Center Mix Level
The amount of gain the decoder should apply to the center channel when downmixing to stereo in Lo/Ro mode.
Lo/Ro Surround Mix Level
The amount of gain the decoder should apply to the surround channel(s) when downmixing to stereo in Lo/Ro mode.
