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| In addition to providing a "normal" cx88-style configuration/capture interface, the audio driver also integrates with FreeBSD's "pcm" audio driver framework, which allows it to be used as an [[http://www.opensound.com/oss.html|OSS]]-compliant audio input device. | In addition to providing a "normal" cx88-style configuration/capture interface, the audio driver also integrates with FreeBSD's "pcm" audio driver framework, which allows it to be used as an [[http://www.opensound.com/oss.html|OSS]]-compliant audio input device. For each cx88 audio device, a /dev/dsp* node will be available for use by any OSS-compatible application. In this case, the CX88_AUDIO_FORMAT ioctl is still necessary to configure the source and broadcast format, and the I2C configuration ioctls will be necessary to configure any frontend devices, but the buffer configuration and capture ioctls should be omitted, as these functions will be handled through the OSS interface. |
Audio
The CX2388x audio stream (Function 1) provides 48KHz, 16-bit stereo PCM audio from an analog TV or FM radio frontend, or from an external audio decoder via an I2S-compliant digital interface. The ioctl(2) interface for the cx88audio driver is defined in /usr/local/include/cx88/cx88_audio_ioctl.h, and is similiar to the interfaces for the MPEG TS and Raw Video drivers. The CX88_AUDIO_FORMAT ioctl is used to specify the broadcast format and/or input source of the audio data, but it does not need to be issued before the audio buffers are configured. If the CX88_AUDIO_FORMAT ioctl is not issued, the driver will default to using an FM radio format with an analog broadcast source.
OSS Interface
In addition to providing a "normal" cx88-style configuration/capture interface, the audio driver also integrates with FreeBSD's "pcm" audio driver framework, which allows it to be used as an OSS-compliant audio input device. For each cx88 audio device, a /dev/dsp* node will be available for use by any OSS-compatible application. In this case, the CX88_AUDIO_FORMAT ioctl is still necessary to configure the source and broadcast format, and the I2C configuration ioctls will be necessary to configure any frontend devices, but the buffer configuration and capture ioctls should be omitted, as these functions will be handled through the OSS interface.