mpd/src/decoder/Client.hxx

/*
 * Copyright 2003-2017 The Music Player Daemon Project
 * http://www.musicpd.org
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#ifndef MPD_DECODER_CLIENT_HXX
#define MPD_DECODER_CLIENT_HXX

#include "check.h"
#include "DecoderCommand.hxx"
#include "Chrono.hxx"
#include "input/Ptr.hxx"
#include "Compiler.h"

#include <stdint.h>

struct AudioFormat;
struct Tag;
struct ReplayGainInfo;
class MixRampInfo;

/**
 * An interface between the decoder plugin and the MPD core.
 */
class DecoderClient {
public:
	/**
	 * Notify the client that it has finished initialization and
	 * that it has read the song's meta data.
	 *
	 * @param audio_format the audio format which is going to be
	 * sent to SubmitData()
	 * @param seekable true if the song is seekable
	 * @param duration the total duration of this song; negative if
	 * unknown
	 */
	virtual void Ready(AudioFormat audio_format,
			   bool seekable, SignedSongTime duration) = 0;

	/**
	 * Determines the pending decoder command.
	 *
	 * @return the current command, or DecoderCommand::NONE if there is no
	 * command pending
	 */
	gcc_pure
	virtual DecoderCommand GetCommand() noexcept = 0;

	/**
	 * Called by the decoder when it has performed the requested command
	 * (dc->command).  This function resets dc->command and wakes up the
	 * player thread.
	 */
	virtual void CommandFinished() = 0;

	/**
	 * Call this when you have received the DecoderCommand::SEEK command.
	 *
	 * @return the destination position for the seek in milliseconds
	 */
	gcc_pure
	virtual SongTime GetSeekTime() noexcept = 0;

	/**
	 * Call this when you have received the DecoderCommand::SEEK command.
	 *
	 * @return the destination position for the seek in frames
	 */
	gcc_pure
	virtual uint64_t GetSeekFrame() noexcept = 0;

	/**
	 * Call this instead of CommandFinished() when seeking has
	 * failed.
	 */
	virtual void SeekError() = 0;

	/**
	 * Open a new #InputStream and wait until it's ready.
	 *
	 * Throws #StopDecoder if DecoderCommand::STOP was received.
	 *
	 * Throws std::runtime_error on error.
	 */
	virtual InputStreamPtr OpenUri(const char *uri) = 0;

	/**
	 * Blocking read from the input stream.
	 *
	 * @param is the input stream to read from
	 * @param buffer the destination buffer
	 * @param length the maximum number of bytes to read
	 * @return the number of bytes read, or 0 if one of the following
	 * occurs: end of file; error; command (like SEEK or STOP).
	 */
	virtual size_t Read(InputStream &is, void *buffer, size_t length) = 0;

	/**
	 * Sets the time stamp for the next data chunk [seconds].  The MPD
	 * core automatically counts it up, and a decoder plugin only needs to
	 * use this function if it thinks that adding to the time stamp based
	 * on the buffer size won't work.
	 */
	virtual void SubmitTimestamp(double t) = 0;

	/**
	 * This function is called by the decoder plugin when it has
	 * successfully decoded block of input data.
	 *
	 * @param is an input stream which is buffering while we are waiting
	 * for the player
	 * @param data the source buffer
	 * @param length the number of bytes in the buffer
	 * @return the current command, or DecoderCommand::NONE if there is no
	 * command pending
	 */
	virtual DecoderCommand SubmitData(InputStream *is,
					  const void *data, size_t length,
					  uint16_t kbit_rate) = 0;

	DecoderCommand SubmitData(InputStream &is,
				  const void *data, size_t length,
				  uint16_t kbit_rate) {
		return SubmitData(&is, data, length, kbit_rate);
	}

	/**
	 * This function is called by the decoder plugin when it has
	 * successfully decoded a tag.
	 *
	 * @param is an input stream which is buffering while we are waiting
	 * for the player
	 * @param tag the tag to send
	 * @return the current command, or DecoderCommand::NONE if there is no
	 * command pending
	 */
	virtual DecoderCommand SubmitTag(InputStream *is, Tag &&tag) = 0 ;

	DecoderCommand SubmitTag(InputStream &is, Tag &&tag) {
		return SubmitTag(&is, std::move(tag));
	}

	/**
	 * Set replay gain values for the following chunks.
	 *
	 * @param replay_gain_info the replay_gain_info object; may be nullptr
	 * to invalidate the previous replay gain values
	 */
	virtual void SubmitReplayGain(const ReplayGainInfo *replay_gain_info) = 0;

	/**
	 * Store MixRamp tags.
	 */
	virtual void SubmitMixRamp(MixRampInfo &&mix_ramp) = 0;
};

#endif