Audio Settings Widget
The audio settings widget offers the user options to configure the channel layout ( mono, stereo, 5.1, …) the sampling rate and the bitrate of the output audio.
Enabling it
You enable the audio settings widget setting the ‘cd_table’ settings in your audio settings group.
How it works
The ‘cd_table’ parameter is a JSON encoded table that specifies all the possibilities available in the target of channel layouts, sampling rates and bitrates. gMT uses this information and the information of the input file to present the user with the available channel layout, bitrate and sampling frequency options that you define on the ‘cd_table’. For example if the input file has 5.1 audio but your cd_table only contains sections for mono and stereo layout gMT will fixate the audio output to stereo, as this is the best setting available in your cd_table given the input. It will also use the default bitrate you specify in the table for the settings, and will show a slider to the user with all the possible bitrates that are defined in the table.
Some common audio codecs inherit the default cd_table but this can be overridden in your profile.
Example
Below is an example of the default for the ‘vorbis’ codec. Note how this is an associative table in JSON format. You define the channel layout first, inside the channel layout you select the supported sampling rates, and inside every sampling rate a list of bitrates that the codec can work on for that combination of channel layout and sampling rate. The ‘default’ bitrate is the one that will be used for transcoding by default.
{ "channels":{ "mono":{ "sr_list":{ "8000":{ "br_list":[ 32000, 64000 ], "default":32000 }, "11025":{ "br_list":[ 32000, 64000 ], "default":32000 }, "16000":{ "br_list":[ 32000, 64000 ], "default":32000 }, "22050":{ "br_list":[ 32000, 64000 ], "default":64000 }, "32000":{ "br_list":[ 64000, 80000, 96000 ], "default":96000 }, "44100":{ "br_list":[ 64000, 80000, 96000, 128000, 160000, 192000, 224000, 256000, 288000, 320000 ], "default":96000 }, "48000":{ "br_list":[ 64000, 80000, 96000, 128000, 160000, 192000, 224000, 256000, 288000, 320000 ], "default":96000 } } }, "stereo":{ "sr_list":{ "8000":{ "br_list":[ 32000, 64000 ], "default":64000 }, "11025":{ "br_list":[ 32000, 64000 ], "default":64000 }, "16000":{ "br_list":[ 32000, 64000 ], "default":64000 }, "22050":{ "br_list":[ 32000, 64000 ], "default":64000 }, "32000":{ "br_list":[ 64000, 80000, 96000, 128000 ], "default":96000 }, "44100":{ "br_list":[ 64000, 80000, 96000, 128000, 160000, 192000, 224000, 256000, 288000, 320000 ], "default":128000 }, "48000":{ "br_list":[ 64000, 80000, 96000, 128000, 160000, 192000, 224000, 256000, 288000, 320000 ], "default":128000 } } } } }
