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/* -*- c-basic-offset: 8 -*- */
#ifndef __AMDTP_H
#define __AMDTP_H
#include <asm/types.h>
#include "ieee1394-ioctl.h"
/* The userspace interface for the Audio & Music Data Transmission
* Protocol driver is really simple. First, open /dev/amdtp, use the
* ioctl to configure format, rate, dimension and either plug or
* channel, then start writing samples.
*
* The formats supported by the driver are listed below.
* AMDTP_FORMAT_RAW corresponds to the AM824 raw format, which can
* carry any number of channels, so use this if you're streaming
* multichannel audio. The AMDTP_FORMAT_IEC958_PCM corresponds to the
* AM824 IEC958 encapsulation without the IEC958 data bit set, using
* AMDTP_FORMAT_IEC958_AC3 will transmit the samples with the data bit
* set, suitable for transmitting compressed AC-3 audio.
*
* The rate field specifies the transmission rate; supported values
* are 32000, 44100, 48000, 88200, 96000, 176400 and 192000.
*
* The dimension field specifies the dimension of the signal, that is,
* the number of audio channels. Only AMDTP_FORMAT_RAW supports
* settings greater than 2.
*
* The mode field specifies which transmission mode to use. The AMDTP
* specifies two different transmission modes: blocking and
* non-blocking. The blocking transmission mode always send a fixed
* number of samples, typically 8, 16 or 32. To exactly match the
* transmission rate, the driver alternates between sending empty and
* non-empty packets. In non-blocking mode, the driver transmits as
* small packets as possible. For example, for a transmission rate of
* 44100Hz, the driver should send 5 41/80 samples in every cycle, but
* this is not possible so instead the driver alternates between
* sending 5 and 6 samples.
*
* The last thing to specify is either the isochronous channel to use
* or the output plug to connect to. If you know what channel the
* destination device will listen on, you can specify the channel
* directly and use the AMDTP_IOC_CHANNEL ioctl. However, if the
* destination device chooses the channel and uses the IEC61883-1 plug
* mechanism, you can specify an output plug to connect to. The
* driver will pick up the channel number from the plug once the
* destination device locks the output plug control register. In this
* case set the plug field and use the AMDTP_IOC_PLUG ioctl.
*
* Having configured the interface, the driver now accepts writes of
* regular 16 bit signed little endian samples, with the channels
* interleaved. For example, 4 channels would look like:
*
* | sample 0 | sample 1 ...
* | ch. 0 | ch. 1 | ch. 2 | ch. 3 | ch. 0 | ...
* | lsb | msb | lsb | msb | lsb | msb | lsb | msb | lsb | msb | ...
*
*/
enum {
AMDTP_FORMAT_RAW,
AMDTP_FORMAT_IEC958_PCM,
AMDTP_FORMAT_IEC958_AC3
};
enum {
AMDTP_MODE_BLOCKING,
AMDTP_MODE_NON_BLOCKING,
};
enum {
AMDTP_INPUT_LE16,
AMDTP_INPUT_BE16,
};
struct amdtp_ioctl {
__u32 format;
__u32 rate;
__u32 dimension;
__u32 mode;
union { __u32 channel; __u32 plug; } u;
};
#endif /* __AMDTP_H */
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