/*
* Copyright (C) 2003-2011 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_PLUGIN_H
#define MPD_ENCODER_PLUGIN_H
#include <glib.h>
#include <assert.h>
#include <stdbool.h>
#include <stddef.h>
struct encoder_plugin;
struct audio_format;
struct config_param;
struct tag;
struct encoder {
const struct encoder_plugin *plugin;
#ifndef NDEBUG
bool open, pre_tag, tag, end;
#endif
};
struct encoder_plugin {
const char *name;
struct encoder *(*init)(const struct config_param *param,
GError **error);
void (*finish)(struct encoder *encoder);
bool (*open)(struct encoder *encoder,
struct audio_format *audio_format,
GError **error);
void (*close)(struct encoder *encoder);
bool (*end)(struct encoder *encoder, GError **error);
bool (*flush)(struct encoder *encoder, GError **error);
bool (*pre_tag)(struct encoder *encoder, GError **error);
bool (*tag)(struct encoder *encoder, const struct tag *tag,
GError **error);
bool (*write)(struct encoder *encoder,
const void *data, size_t length,
GError **error);
size_t (*read)(struct encoder *encoder, void *dest, size_t length);
const char *(*get_mime_type)(struct encoder *encoder);
};
/**
* Initializes an encoder object. This should be used by encoder
* plugins to initialize their base class.
*/
static inline void
encoder_struct_init(struct encoder *encoder,
const struct encoder_plugin *plugin)
{
encoder->plugin = plugin;
#ifndef NDEBUG
encoder->open = false;
#endif
}
/**
* Creates a new encoder object.
*
* @param plugin the encoder plugin
* @param param optional configuration
* @param error location to store the error occurring, or NULL to ignore errors.
* @return an encoder object on success, NULL on failure
*/
static inline struct encoder *
encoder_init(const struct encoder_plugin *plugin,
const struct config_param *param, GError **error)
{
return plugin->init(param, error);
}
/**
* Frees an encoder object.
*
* @param encoder the encoder
*/
static inline void
encoder_finish(struct encoder *encoder)
{
assert(!encoder->open);
encoder->plugin->finish(encoder);
}
/**
* Opens an encoder object. You must call this prior to using it.
* Before you free it, you must call encoder_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 encoder the encoder
* @param audio_format the encoder's input audio format; the plugin
* may modify the struct to adapt it to its abilities
* @param error location to store the error occurring, or NULL to ignore errors.
* @return true on success
*/
static inline bool
encoder_open(struct encoder *encoder, struct audio_format *audio_format,
GError **error)
{
assert(!encoder->open);
bool success = encoder->plugin->open(encoder, audio_format, error);
#ifndef NDEBUG
encoder->open = success;
encoder->pre_tag = encoder->tag = encoder->end = false;
#endif
return success;
}
/**
* Closes an encoder object. This disables the encoder, and readies
* it for reusal by calling encoder_open() again.
*
* @param encoder the encoder
*/
static inline void
encoder_close(struct encoder *encoder)
{
assert(encoder->open);
if (encoder->plugin->close != NULL)
encoder->plugin->close(encoder);
#ifndef NDEBUG
encoder->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
* @param error location to store the error occuring, or NULL to ignore errors.
* @return true on success
*/
static inline bool
encoder_end(struct encoder *encoder, GError **error)
{
assert(encoder->open);
assert(!encoder->end);
#ifndef NDEBUG
encoder->end = true;
#endif
/* this method is optional */
return encoder->plugin->end != NULL
? 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
* @param error location to store the error occurring, or NULL to ignore errors.
* @return true on success
*/
static inline bool
encoder_flush(struct encoder *encoder, GError **error)
{
assert(encoder->open);
assert(!encoder->pre_tag);
assert(!encoder->tag);
assert(!encoder->end);
/* this method is optional */
return encoder->plugin->flush != NULL
? 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
* @param tag the tag object
* @param error location to store the error occuring, or NULL to ignore errors.
* @return true on success
*/
static inline bool
encoder_pre_tag(struct encoder *encoder, GError **error)
{
assert(encoder->open);
assert(!encoder->pre_tag);
assert(!encoder->tag);
assert(!encoder->end);
/* this method is optional */
bool success = encoder->plugin->pre_tag != NULL
? 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
* @param error location to store the error occurring, or NULL to ignore errors.
* @return true on success
*/
static inline bool
encoder_tag(struct encoder *encoder, const struct tag *tag, GError **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 != NULL
? 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
* @param error location to store the error occurring, or NULL to ignore errors.
* @return true on success
*/
static inline bool
encoder_write(struct encoder *encoder, const void *data, size_t length,
GError **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.
*
* @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(struct 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.
*
* @param plugin the encoder plugin
* @return an constant string, NULL on failure
*/
static inline const char *
encoder_get_mime_type(struct encoder *encoder)
{
/* this method is optional */
return encoder->plugin->get_mime_type != NULL
? encoder->plugin->get_mime_type(encoder)
: NULL;
}
#endif
