It is also possible to configure Fldigi with File I/O only, which is useful for testing the application without an interface to the sound card. On Windows Fldigi uses the Portaudio sound driver only. Each of the appropriate libraries must be present on the computer to use that particular sound i/o. On Linux Fldigi can interface to the sound card using either the OSS, the Portaudio, or the PulseAudio. Select the SndCrd tab on the configuration dialog. Use the PortAudio and select the device from the list(s). If your audio device does not support full duplex (some blue tooth devices are in this category), then uncheck the "Device supports full duplex" control. The device will be opened for both read and write. Most audio devices will support full duplex operation. Note that it has not been updated to support user-configurable sample rates. The OSS backend should be used only as a last resort. As with PulseAudio, you can select different capture and playback audio devices. PortAudio is also the best way to access JACK, through which you can use other programs as audio sources/sinks – particularly useful with SDR software. Otherwise, use PortAudio and select a device from the list(s). Use PulseAudio if your Linux distro ships it, and you already have the pulseaudio daemon running (this is the case with Fedora 8/9 and Ubuntu 8.04, probably also with openSUSE 11.0). In the future it might be possible to replace all of these with a single backend, without any loss of functionality, performance, sound system or platform support. It remembers which hardware is used for each application it serves, and it remembers the mixer levels associated with that application It provides mixer controls for input and output audio streams It makes it easier to run multiple fldigi instances (all accessing the same sound card). It can stream audio over the network, and It can take care of the resampling and volume control for us, Fldigi supports it mainly because many Linux distributions are now integrating it with their desktops, but also because it has a few interesting features: PulseAudio is more than an audio hardware access layer refer to its website for a summary of what it does. The PortAudio backend was written subsequently to support OSS on Linux and FreeBSD, ALSA and JACK on Linux, CoreAudio on OS X, and also the various sound APIs on Windows – all through the same PortAudio library. Its only advantage, as an audio backend, is that it's simple and doesn't require any external libraries. It works with the Linux sound system of the same name, which has now been replaced by ALSA but is still supported via an emulation layer. OSS was the first audio backend in fldigi. PortAudio, PulseAudio and OSS are different ways in which fldigi can access your sound card through the various sound systems.
0 Comments
Leave a Reply. |