encoder_api: convert to C++
This commit is contained in:
Max Kellermann
328
src/EncoderPlugin.hxx
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328
src/EncoderPlugin.hxx
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/*
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* Copyright (C) 2003-2013 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#ifndef MPD_ENCODER_PLUGIN_HXX
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#define MPD_ENCODER_PLUGIN_HXX
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#include "gerror.h"
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#include <assert.h>
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#include <stdbool.h>
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#include <stddef.h>
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struct EncoderPlugin;
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struct audio_format;
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struct config_param;
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struct tag;
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struct Encoder {
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const EncoderPlugin &plugin;
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#ifndef NDEBUG
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bool open, pre_tag, tag, end;
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#endif
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explicit Encoder(const EncoderPlugin &_plugin)
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:plugin(_plugin)
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#ifndef NDEBUG
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, open(false)
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#endif
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{}
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};
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struct EncoderPlugin {
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const char *name;
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Encoder *(*init)(const struct config_param *param,
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GError **error);
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void (*finish)(Encoder *encoder);
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bool (*open)(Encoder *encoder,
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struct audio_format *audio_format,
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GError **error);
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void (*close)(Encoder *encoder);
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bool (*end)(Encoder *encoder, GError **error);
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bool (*flush)(Encoder *encoder, GError **error);
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bool (*pre_tag)(Encoder *encoder, GError **error);
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bool (*tag)(Encoder *encoder, const struct tag *tag,
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GError **error);
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bool (*write)(Encoder *encoder,
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const void *data, size_t length,
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GError **error);
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size_t (*read)(Encoder *encoder, void *dest, size_t length);
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const char *(*get_mime_type)(Encoder *encoder);
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};
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/**
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* Creates a new encoder object.
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*
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* @param plugin the encoder plugin
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* @param param optional configuration
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* @param error location to store the error occurring, or NULL to ignore errors.
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* @return an encoder object on success, NULL on failure
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*/
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static inline Encoder *
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encoder_init(const EncoderPlugin &plugin, const config_param *param,
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GError **error_r)
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{
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return plugin.init(param, error_r);
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}
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/**
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* Frees an encoder object.
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*
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* @param encoder the encoder
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*/
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static inline void
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encoder_finish(Encoder *encoder)
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{
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assert(!encoder->open);
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encoder->plugin.finish(encoder);
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}
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/**
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* Opens an encoder object. You must call this prior to using it.
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* Before you free it, you must call encoder_close(). You may open
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* and close (reuse) one encoder any number of times.
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*
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* After this function returns successfully and before the first
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* encoder_write() call, you should invoke encoder_read() to obtain
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* the file header.
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*
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* @param encoder the encoder
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* @param audio_format the encoder's input audio format; the plugin
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* may modify the struct to adapt it to its abilities
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* @param error location to store the error occurring, or NULL to ignore errors.
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* @return true on success
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*/
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static inline bool
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encoder_open(Encoder *encoder, struct audio_format *audio_format,
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GError **error)
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{
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assert(!encoder->open);
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bool success = encoder->plugin.open(encoder, audio_format, error);
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#ifndef NDEBUG
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encoder->open = success;
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encoder->pre_tag = encoder->tag = encoder->end = false;
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#endif
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return success;
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}
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/**
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* Closes an encoder object. This disables the encoder, and readies
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* it for reusal by calling encoder_open() again.
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*
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* @param encoder the encoder
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*/
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static inline void
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encoder_close(Encoder *encoder)
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{
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assert(encoder->open);
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if (encoder->plugin.close != NULL)
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encoder->plugin.close(encoder);
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#ifndef NDEBUG
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encoder->open = false;
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#endif
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}
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/**
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* Ends the stream: flushes the encoder object, generate an
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* end-of-stream marker (if applicable), make everything which might
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* currently be buffered available by encoder_read().
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*
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* After this function has been called, the encoder may not be usable
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* for more data, and only encoder_read() and encoder_close() can be
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* called.
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*
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* @param encoder the encoder
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* @param error location to store the error occuring, or NULL to ignore errors.
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* @return true on success
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*/
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static inline bool
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encoder_end(Encoder *encoder, GError **error)
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{
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assert(encoder->open);
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assert(!encoder->end);
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#ifndef NDEBUG
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encoder->end = true;
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#endif
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/* this method is optional */
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return encoder->plugin.end != NULL
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? encoder->plugin.end(encoder, error)
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: true;
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}
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/**
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* Flushes an encoder object, make everything which might currently be
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* buffered available by encoder_read().
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*
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* @param encoder the encoder
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* @param error location to store the error occurring, or NULL to ignore errors.
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* @return true on success
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*/
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static inline bool
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encoder_flush(Encoder *encoder, GError **error)
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{
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assert(encoder->open);
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assert(!encoder->pre_tag);
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assert(!encoder->tag);
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assert(!encoder->end);
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/* this method is optional */
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return encoder->plugin.flush != NULL
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? encoder->plugin.flush(encoder, error)
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: true;
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}
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/**
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* Prepare for sending a tag to the encoder. This is used by some
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* encoders to flush the previous sub-stream, in preparation to begin
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* a new one.
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*
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* @param encoder the encoder
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* @param tag the tag object
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* @param error location to store the error occuring, or NULL to ignore errors.
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* @return true on success
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*/
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static inline bool
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encoder_pre_tag(Encoder *encoder, GError **error)
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{
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assert(encoder->open);
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assert(!encoder->pre_tag);
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assert(!encoder->tag);
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assert(!encoder->end);
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/* this method is optional */
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bool success = encoder->plugin.pre_tag != NULL
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? encoder->plugin.pre_tag(encoder, error)
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: true;
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#ifndef NDEBUG
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encoder->pre_tag = success;
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#endif
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return success;
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}
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/**
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* Sends a tag to the encoder.
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*
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* Instructions: call encoder_pre_tag(); then obtain flushed data with
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* encoder_read(); finally call encoder_tag().
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*
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* @param encoder the encoder
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* @param tag the tag object
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* @param error location to store the error occurring, or NULL to ignore errors.
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* @return true on success
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*/
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static inline bool
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encoder_tag(Encoder *encoder, const struct tag *tag, GError **error)
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{
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assert(encoder->open);
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assert(!encoder->pre_tag);
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assert(encoder->tag);
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assert(!encoder->end);
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#ifndef NDEBUG
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encoder->tag = false;
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#endif
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/* this method is optional */
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return encoder->plugin.tag != NULL
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? encoder->plugin.tag(encoder, tag, error)
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: true;
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}
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/**
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* Writes raw PCM data to the encoder.
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*
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* @param encoder the encoder
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* @param data the buffer containing PCM samples
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* @param length the length of the buffer in bytes
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* @param error location to store the error occurring, or NULL to ignore errors.
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* @return true on success
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*/
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static inline bool
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encoder_write(Encoder *encoder, const void *data, size_t length,
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GError **error)
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{
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assert(encoder->open);
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assert(!encoder->pre_tag);
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assert(!encoder->tag);
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assert(!encoder->end);
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return encoder->plugin.write(encoder, data, length, error);
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}
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/**
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* Reads encoded data from the encoder.
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*
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* Call this repeatedly until no more data is returned.
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*
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* @param encoder the encoder
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* @param dest the destination buffer to copy to
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* @param length the maximum length of the destination buffer
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* @return the number of bytes written to #dest
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*/
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static inline size_t
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encoder_read(Encoder *encoder, void *dest, size_t length)
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{
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assert(encoder->open);
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assert(!encoder->pre_tag || !encoder->tag);
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#ifndef NDEBUG
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if (encoder->pre_tag) {
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encoder->pre_tag = false;
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encoder->tag = true;
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}
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#endif
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return encoder->plugin.read(encoder, dest, length);
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}
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/**
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* Get mime type of encoded content.
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*
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* @param plugin the encoder plugin
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* @return an constant string, NULL on failure
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*/
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static inline const char *
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encoder_get_mime_type(Encoder *encoder)
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{
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/* this method is optional */
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return encoder->plugin.get_mime_type != NULL
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? encoder->plugin.get_mime_type(encoder)
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: NULL;
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}
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#endif
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