/*
* Copyright (C) 2003-2015 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_ENCODER_INTERFACE_HXX
#define MPD_ENCODER_INTERFACE_HXX
#include "EncoderPlugin.hxx"
#include <assert.h>
struct Encoder {
const EncoderPlugin &plugin;
#ifndef NDEBUG
bool open, pre_tag, tag, end;
#endif
explicit Encoder(const EncoderPlugin &_plugin)
:plugin(_plugin)
#ifndef NDEBUG
, open(false)
#endif
{}
/**
* Frees an #Encoder object.
*/
void Dispose() {
assert(!open);
plugin.finish(this);
}
/**
* Opens the object. You must call this prior to using it.
* Before you free it, you must call Close(). You may open
* and close (reuse) one encoder any number of times.
*
* After this function returns successfully and before the
* first encoder_write() call, you should invoke
* encoder_read() to obtain the file header.
*
* @param audio_format the encoder's input audio format; the plugin
* may modify the struct to adapt it to its abilities
* @return true on success
*/
bool Open(AudioFormat &audio_format, Error &error) {
assert(!open);
bool success = plugin.open(this, audio_format, error);
#ifndef NDEBUG
open = success;
pre_tag = tag = end = false;
#endif
return success;
}
/**
* Closes the object. This disables the encoder, and readies
* it for reusal by calling Open() again.
*/
void Close() {
assert(open);
if (plugin.close != nullptr)
plugin.close(this);
#ifndef NDEBUG
open = false;
#endif
}
};
/**
* Ends the stream: flushes the encoder object, generate an
* end-of-stream marker (if applicable), make everything which might
* currently be buffered available by encoder_read().
*
* After this function has been called, the encoder may not be usable
* for more data, and only encoder_read() and Encoder::Close() can be
* called.
*
* @param encoder the encoder
* @return true on success
*/
static inline bool
encoder_end(Encoder *encoder, Error &error)
{
assert(encoder->open);
assert(!encoder->end);
#ifndef NDEBUG
encoder->end = true;
#endif
/* this method is optional */
return encoder->plugin.end != nullptr
? encoder->plugin.end(encoder, error)
: true;
}
/**
* Flushes an encoder object, make everything which might currently be
* buffered available by encoder_read().
*
* @param encoder the encoder
* @return true on success
*/
static inline bool
encoder_flush(Encoder *encoder, Error &error)
{
assert(encoder->open);
assert(!encoder->pre_tag);
assert(!encoder->tag);
assert(!encoder->end);
/* this method is optional */
return encoder->plugin.flush != nullptr
? encoder->plugin.flush(encoder, error)
: true;
}
/**
* Prepare for sending a tag to the encoder. This is used by some
* encoders to flush the previous sub-stream, in preparation to begin
* a new one.
*
* @param encoder the encoder
* @return true on success
*/
static inline bool
encoder_pre_tag(Encoder *encoder, Error &error)
{
assert(encoder->open);
assert(!encoder->pre_tag);
assert(!encoder->tag);
assert(!encoder->end);
/* this method is optional */
bool success = encoder->plugin.pre_tag != nullptr
? encoder->plugin.pre_tag(encoder, error)
: true;
#ifndef NDEBUG
encoder->pre_tag = success;
#endif
return success;
}
/**
* Sends a tag to the encoder.
*
* Instructions: call encoder_pre_tag(); then obtain flushed data with
* encoder_read(); finally call encoder_tag().
*
* @param encoder the encoder
* @param tag the tag object
* @return true on success
*/
static inline bool
encoder_tag(Encoder *encoder, const Tag &tag, Error &error)
{
assert(encoder->open);
assert(!encoder->pre_tag);
assert(encoder->tag);
assert(!encoder->end);
#ifndef NDEBUG
encoder->tag = false;
#endif
/* this method is optional */
return encoder->plugin.tag != nullptr
? encoder->plugin.tag(encoder, tag, error)
: true;
}
/**
* Writes raw PCM data to the encoder.
*
* @param encoder the encoder
* @param data the buffer containing PCM samples
* @param length the length of the buffer in bytes
* @return true on success
*/
static inline bool
encoder_write(Encoder *encoder, const void *data, size_t length,
Error &error)
{
assert(encoder->open);
assert(!encoder->pre_tag);
assert(!encoder->tag);
assert(!encoder->end);
return encoder->plugin.write(encoder, data, length, error);
}
/**
* Reads encoded data from the encoder.
*
* Call this repeatedly until no more data is returned.
*
* @param encoder the encoder
* @param dest the destination buffer to copy to
* @param length the maximum length of the destination buffer
* @return the number of bytes written to #dest
*/
static inline size_t
encoder_read(Encoder *encoder, void *dest, size_t length)
{
assert(encoder->open);
assert(!encoder->pre_tag || !encoder->tag);
#ifndef NDEBUG
if (encoder->pre_tag) {
encoder->pre_tag = false;
encoder->tag = true;
}
#endif
return encoder->plugin.read(encoder, dest, length);
}
/**
* Get mime type of encoded content.
*
* @return an constant string, nullptr on failure
*/
static inline const char *
encoder_get_mime_type(Encoder *encoder)
{
/* this method is optional */
return encoder->plugin.get_mime_type != nullptr
? encoder->plugin.get_mime_type(encoder)
: nullptr;
}
#endif
