57 lines
2.0 KiB
Plaintext
57 lines
2.0 KiB
Plaintext
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Old versus new PCM API (values returned using indirect pointers)
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================================================================
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From the binary compatibility view, there is no change. For compilation,
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1.0 ALSA applications do not need any change. The older applications must
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use this include sequence:
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#define ALSA_PCM_OLD_HW_PARAMS_API
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#define ALSA_PCM_OLD_SW_PARAMS_API
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#include <alsa/asoundlib.h>
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If you use already the new API, you may remove old defines selecting
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this API, because they are no longer used:
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#define ALSA_PCM_NEW_HW_PARAMS_API
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#define ALSA_PCM_NEW_SW_PARAMS_API
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Verbose Error Messages
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======================
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Since version 1.0.8, assert() for some non-fatal errors are removed
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and error messages are no longer shown to stderr as default. Instead,
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the error messages appear only when the environment variable
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LIBASOUND_DEBUG is set (to a non-empty value).
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When LIBASOUND_DEBUG=1 is set, the errors in hw_params configuration
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will be dumped to stderr. Note that this will show even the non-fatal
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errors of plug layer (trial-and-error of parameters).
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This feature is disabled when --with-debug=no is passed to configure,
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i.e. no strict checking is done in alsa-lib.
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In addition, when --enable-debug-assert configure option is given and
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when LIBASOUND_DEBUG_ASSERT=1 is set, the default error message
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handler can call assert() to catch with a debugger. This feature was
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formerly activated via LIBASOUND_DEBUG=2.
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Blocking Open Mode
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==================
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The default behavior of blocking at snd_pcm_open is changed to
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non-blocking since version 1.0.11. That is, snd_pcm_open() returns
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-EAGAIN immediately when the device is in use and cannot be opened,
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while the function was blocked in the former version. This influences
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only on the opening behavior. The behavior of the further access,
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read/write, poll or commit, are not changed. They follow the extra
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flag argument of snd_pcm_open() as well as the former version.
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For taking back the compatible behavior of open blocking mode, set
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defaults.pcm.nonblock 0
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in /etc/asound.conf or ~/.asoundrc file.
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