99 lines
2.9 KiB
C++
99 lines
2.9 KiB
C++
/*
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* \brief Audio-out session interface
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* \author Norman Feske
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* \author Sebastian Sumpf
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* \author Christian Helmuth
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* \author Stefan Kalkowski
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* \date 2009-12-02
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*
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* A audio-out session corresponds to one output channel, which can be used to
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* transmit audio frames. Payload is communicated over the packet-stream
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* interface set up between 'Session_client' and 'Session_server'. The term
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* _channel_ means literally one audio channel, e.g. front left or rear center.
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* Therefore, a standard two-channel stereo track needs two audio-out sessions
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* - one for "front left" and one for "front right". The channel format is
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* FLOAT_LE currently.
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*
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* Audio channel identifiers (loosly related to WAV channels) are:
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*
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* * Front left, right, center
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* * LFE (low frequency effets, subwoofer)
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* * Rear left, right, center
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*
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* For example, consumer-oriented 6-channel (5.1) audio uses front
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* left/right/center, rear left/right and LFE.
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*/
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/*
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* Copyright (C) 2009-2012 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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#ifndef _INCLUDE__AUDIO_OUT_SESSION__AUDIO_OUT_SESSION_H_
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#define _INCLUDE__AUDIO_OUT_SESSION__AUDIO_OUT_SESSION_H_
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#include <base/signal.h>
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#include <base/rpc.h>
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#include <dataspace/capability.h>
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#include <audio_out_session/capability.h>
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#include <packet_stream_tx/packet_stream_tx.h>
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#include <session/session.h>
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namespace Audio_out {
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enum {
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QUEUE_SIZE = 16, /* buffer queue size */
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FRAME_SIZE = 4, /* frame size in bytes */
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PERIOD = 1024 /* frames per period */
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};
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struct Session : Genode::Session
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{
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typedef Packet_stream_policy<Packet_descriptor,
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QUEUE_SIZE, QUEUE_SIZE,
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float> Policy;
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typedef Packet_stream_tx::Channel<Policy> Channel;
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static const char *service_name() { return "Audio_out"; }
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virtual ~Session() { }
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/**
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* Request client-side packet-stream interface of channel
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*/
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virtual Channel::Source *stream() { return 0; }
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/**
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* Flush the audio buffer
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*/
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virtual void flush(void) = 0;
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/**
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* Set synchronization session
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*
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* \param audio_out_session synchronization session
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*
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* Session can be kept in sync (or bundled) using this function, for
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* example, the left and right stero channels. A session has exactly
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* one synchronization session.
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*/
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virtual void sync_session(Session_capability audio_out_session) = 0;
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/*******************
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** RPC interface **
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*******************/
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GENODE_RPC(Rpc_flush, void, flush);
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GENODE_RPC(Rpc_sync_session, void, sync_session, Session_capability);
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GENODE_RPC(Rpc_channel_cap, Genode::Capability<Channel>, channel_cap);
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GENODE_RPC_INTERFACE(Rpc_flush, Rpc_sync_session, Rpc_channel_cap);
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};
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}
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#endif /* _INCLUDE__AUDIO_OUT_SESSION__AUDIO_OUT_SESSION_H_ */
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