AudioSetup

Setting up audio in MythTV 0.25 and beyond

Audio setup is pretty straightforward in MythTV.

Device names are those that can be found with the aplay command, specifically aplay -L. Not that anybody should ever need to use those. Most people will find that the default device will work just fine.

The 'rescan' button will make mythfrontend re-scan audio devices & check their capabilities.

The 'Speaker configuration' field is where the maximum number of speakers the audio system will support is set. Set this to the maximum number of speakers in your audio setup.

If more than stereo sound is supported, upconverting stereo to 5.1 will be possible & the quality of upmixing can be set.

The 'test' button will load a page which allows the audio system to be tested, to ensure channel outputs are working and are correctly imaged (i.e. front left is front left etc)

A 5.1 setup is shown below:

Special configurations

Example: Analogue stereo output, but use SPDIF for AC3/DTS passthrough.

Sometimes it's necessary for various reasons, to specify a separate digital output device so that any digital surround output is sent to a device other than the main audio device. Some motherboard audio chipsets do not show digital passthrough capability & their digital output has to be added separately.

To do this, the 'Separate digital output device' checkbox has to be ticked and the correct name of the device added to the 'Digital output device' field.

If aplay -L lists the iec958 (SPDIF) device as 'iec958:CARD=Intel,DEV=0' one would use ALSA:iec958:{ AES0 0x02 }. The {AES0 0x02} part tells mythfrontend to set the port flag to raw data (i.e. pass through digital surround sound streams as-is).

Once set, return to the main page & use the 'rescan' button. The 'Dolby Digital' & 'DTS' boxes should be visible. Ensure they are checked. Assuming the target sound system has more than two speakers set the speaker configuration accordingly.