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730ff79841
Original commit message from CVS: fixing alsa step 2: complete rewrite of data transfer. The whole stuff is clean enough to go from there now. License change to LGPL, since no copied code is left now. Missing: - alsasrc - resetting format - corner cases - testsuite
62 lines
2.2 KiB
Text
62 lines
2.2 KiB
Text
0.0 History
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-----------
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This plugin was originally written by Thomas Nyberg <thomas@codefactory.se> for
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ALSA 0.5.x. It was updated and changed quite a bit in September 2001 by Andy
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Wingo for use with ALSA 0.9.x. It was rewritten in great part again by Benjamin
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Otte in January/February 2003.
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1.0 Introduction
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----------------
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This plugin was designed for use with ALSA 0.9.x, using other versions most
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assuredly will not work.
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The plugin will probe which cards and pcm-devices that are availible, and then
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it tries to determine their capabilities. This will allow the use of multiple
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cards with multiple pcm-devices - at the same time! Since I only have one card
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on my system, as of yet, I haven't had the chance to try this out.
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2.0 How to use it
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-----------------
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Since we can have multiple soundcards, each having the same name - and also
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multiple pcm-devices on each card, a problem with naming occurs. When
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the alsa-plugins are initialized, a factory is created for each card and
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pcm-device on the system.
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On my desktop, I have the following:
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wingo@cebreiro:~/src/gstreamer$ gstreamer-inspect alsa
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INFO ( 339:-1) Initializing GStreamer Core Library
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INFO ( 339:-1) CPU features: (808009bf) MMX 3DNOW
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Plugin Details:
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Name: alsa
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Long Name: Alsa plugin library
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Filename: /usr/lib/gst/libalsa.so
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ES1370/1_sink: ES1370 DAC2/ADC
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ES1370/2_sink: ES1370 DAC1
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ES1370/1_src: ES1370 DAC2/ADC
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alsasink: default alsa sink
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alsasrc: default alsa src
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My particular card has 4 channel out and 2 channel in. As you can see, each of
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these devices are stereo. The alsasink and alsasrc elements correspond to the
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default alsa devices.
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3.0 Where to look for other ALSA drivers
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----------------------------------------
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ALSA 0.9 isn't very well documented, so we had to rely on a number of different
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sources for guidance. Sources of inspiration include JACK's alsa driver
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(available in jack's cvs tree, http://jack.sourceforge.net/), the alsa2 driver
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of mplayer (http://www.mplayerhq.hu) and the pcm.c example from the ALSA library
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itself.
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(http://www.alsa-project.org/alsa-doc/alsa-lib/_2test_2pcm_8c-example.html)
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4.0 License
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-----------
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This plugin is licensed under the Lesser General Public License (LGPL). See the
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file COPYING in the top source directory.
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