gstreamer/gst/gstbufferpool.h

/* GStreamer
 * Copyright (C) 2010 Wim Taymans <wim.taymans@gmail.com>
 *
 * gstbufferpool.h: Header for GstBufferPool object
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */


#ifndef __GST_BUFFER_POOL_H__
#define __GST_BUFFER_POOL_H__

#include <gst/gstminiobject.h>
#include <gst/gstpad.h>
#include <gst/gstbuffer.h>

G_BEGIN_DECLS

typedef struct _GstBufferPoolPrivate GstBufferPoolPrivate;
typedef struct _GstBufferPoolClass GstBufferPoolClass;

#define GST_TYPE_BUFFER_POOL                 (gst_buffer_pool_get_type())
#define GST_IS_BUFFER_POOL(obj)              (G_TYPE_CHECK_INSTANCE_TYPE ((obj), GST_TYPE_BUFFER_POOL))
#define GST_IS_BUFFER_POOL_CLASS(klass)      (G_TYPE_CHECK_CLASS_TYPE ((klass), GST_TYPE_BUFFER_POOL))
#define GST_BUFFER_POOL_GET_CLASS(obj)       (G_TYPE_INSTANCE_GET_CLASS ((obj), GST_TYPE_BUFFER_POOL, GstBufferPoolClass))
#define GST_BUFFER_POOL(obj)                 (G_TYPE_CHECK_INSTANCE_CAST ((obj), GST_TYPE_BUFFER_POOL, GstBufferPool))
#define GST_BUFFER_POOL_CLASS(klass)         (G_TYPE_CHECK_CLASS_CAST ((klass), GST_TYPE_BUFFER_POOL, GstBufferPoolClass))
#define GST_BUFFER_POOL_CAST(obj)            ((GstBufferPool *)(obj))

/**
 * GstBufferPoolAcquireFlags:
 * @GST_BUFFER_POOL_ACQUIRE_FLAG_NONE: no flags
 * @GST_BUFFER_POOL_ACQUIRE_FLAG_KEY_UNIT: buffer is keyframe
 * @GST_BUFFER_POOL_ACQUIRE_FLAG_DONTWAIT: when the bufferpool is empty, acquire_buffer
 * will by default block until a buffer is released into the pool again. Setting
 * this flag makes acquire_buffer return #GST_FLOW_EOS instead of blocking.
 * @GST_BUFFER_POOL_ACQUIRE_FLAG_DISCONT: buffer is discont
 * @GST_BUFFER_POOL_ACQUIRE_FLAG_LAST: last flag, subclasses can use private flags
 *    starting from this value.
 *
 * Additional flags to control the allocation of a buffer
 */
typedef enum {
  GST_BUFFER_POOL_ACQUIRE_FLAG_NONE     = 0,
  GST_BUFFER_POOL_ACQUIRE_FLAG_KEY_UNIT = (1 << 0),
  GST_BUFFER_POOL_ACQUIRE_FLAG_DONTWAIT = (1 << 1),
  GST_BUFFER_POOL_ACQUIRE_FLAG_DISCONT  = (1 << 2),
  GST_BUFFER_POOL_ACQUIRE_FLAG_LAST     = (1 << 16),
} GstBufferPoolAcquireFlags;

typedef struct _GstBufferPoolAcquireParams GstBufferPoolAcquireParams;

/**
 * GstBufferPoolAcquireParams:
 * @format: the format of @start and @stop
 * @start: the start position
 * @stop: the stop position
 * @flags: additional flags
 *
 * Parameters passed to the gst_buffer_pool_acquire_buffer() function to control the
 * allocation of the buffer.
 *
 * The default implementation ignores the @start and @stop members but other
 * implementations can use this extra information to decide what buffer to
 * return.
 */
struct _GstBufferPoolAcquireParams {
  GstFormat                 format;
  gint64                    start;
  gint64                    stop;
  GstBufferPoolAcquireFlags flags;

  /*< private >*/
  gpointer _gst_reserved[GST_PADDING];
};

/**
 * GST_BUFFER_POOL_IS_FLUSHING:
 * @pool: a GstBufferPool
 *
 * Check if the bufferpool is flushing. Subclasses might want to check the
 * state of the pool in the acquire function.
 */
#define GST_BUFFER_POOL_IS_FLUSHING(pool)  (g_atomic_int_get (&pool->flushing))

/**
 * GstBufferPool:
 * @object: the parent structure
 * @flushing: whether the pool is currently gathering back outstanding buffers
 *
 * The structure of a #GstBufferPool. Use the associated macros to access the public
 * variables.
 */
struct _GstBufferPool {
  GstObject            object;

  /*< protected >*/
  gint                 flushing;

  /*< private >*/
  GstBufferPoolPrivate *priv;

  gpointer _gst_reserved[GST_PADDING];
};

/**
 * GstBufferPoolClass:
 * @object_class:  Object parent class
 *
 * The #GstBufferPool class.
 */
struct _GstBufferPoolClass {
  GstObjectClass    object_class;

  /*< public >*/

  /**
   * GstBufferPoolClass::get_options:
   * @pool: the #GstBufferPool
   *
   * Get a list of options supported by this pool
   *
   * Returns: (array zero-terminated=1) (transfer none): a %NULL terminated array
   *          of strings.
   */
  const gchar ** (*get_options)    (GstBufferPool *pool);

  /**
   * GstBufferPoolClass::set_config:
   * @pool: the #GstBufferPool
   * @config: the required configuration
   *
   * Apply the bufferpool configuration. The default configuration will parse
   * the default config parameters.
   *
   * Returns: whether the configuration could be set.
   */
  gboolean       (*set_config)     (GstBufferPool *pool, GstStructure *config);

  /**
   * GstBufferPoolClass::start:
   * @pool: the #GstBufferPool
   *
   * Start the bufferpool. The default implementation will preallocate
   * min-buffers buffers and put them in the queue.
   *
   * Returns: whether the pool could be started.
   */
  gboolean       (*start)          (GstBufferPool *pool);

  /**
   * GstBufferPoolClass::stop:
   * @pool: the #GstBufferPool
   *
   * Stop the bufferpool. the default implementation will free the
   * preallocated buffers. This function is called when all the buffers are
   * returned to the pool.
   *
   * Returns: whether the pool could be stopped.
   */
  gboolean       (*stop)           (GstBufferPool *pool);

  /**
   * GstBufferPoolClass::acquire_buffer:
   * @pool: the #GstBufferPool
   * @buffer: (out): a location for a #GstBuffer
   * @params: (transfer none) (allow-none): parameters.
   *
   * Get a new buffer from the pool. The default implementation
   * will take a buffer from the queue and optionally wait for a buffer to
   * be released when there are no buffers available.
   *
   * Returns: a #GstFlowReturn such as %GST_FLOW_FLUSHING when the pool is
   * inactive.
   */
  GstFlowReturn  (*acquire_buffer) (GstBufferPool *pool, GstBuffer **buffer,
                                    GstBufferPoolAcquireParams *params);

  /**
   * GstBufferPoolClass::alloc_buffer:
   * @pool: the #GstBufferPool
   * @buffer: (out): a location for a #GstBuffer
   * @params: (transfer none) (allow-none): parameters.
   *
   * Allocate a buffer. the default implementation allocates
   * buffers from the configured memory allocator and with the configured
   * parameters. All metadata that is present on the allocated buffer will
   * be marked as #GST_META_FLAG_POOLED and #GST_META_FLAG_LOCKED and will
   * not be removed from the buffer in #GstBufferPoolClass::reset_buffer.
   * The buffer should have the #GST_BUFFER_FLAG_TAG_MEMORY cleared.
   *
   * Returns: a #GstFlowReturn to indicate whether the allocation was
   * successful.
   */
  GstFlowReturn  (*alloc_buffer)   (GstBufferPool *pool, GstBuffer **buffer,
                                    GstBufferPoolAcquireParams *params);

  /**
   * GstBufferPoolClass::reset_buffer:
   * @pool: the #GstBufferPool
   * @buffer: the #GstBuffer to reset
   *
   * Reset the buffer to its state when it was freshly allocated.
   * The default implementation will clear the flags, timestamps and
   * will remove the metadata without the #GST_META_FLAG_POOLED flag (even
   * the metadata with #GST_META_FLAG_LOCKED). If the
   * #GST_BUFFER_FLAG_TAG_MEMORY was set, this function can also try to
   * restore the memory and clear the #GST_BUFFER_FLAG_TAG_MEMORY again.
   */
  void           (*reset_buffer)   (GstBufferPool *pool, GstBuffer *buffer);

  /**
   * GstBufferPoolClass::release_buffer:
   * @pool: the #GstBufferPool
   * @buffer: the #GstBuffer to release
   *
   * Release a buffer back in the pool. The default implementation
   * will put the buffer back in the queue and notify any
   * blocking #GstBufferPoolClass::acquire_buffer calls when the
   * #GST_BUFFER_FLAG_TAG_MEMORY is not set on the buffer.
   * If #GST_BUFFER_FLAG_TAG_MEMORY is set, the buffer will be freed with
   * #GstBufferPoolClass::free_buffer.
   */
  void           (*release_buffer) (GstBufferPool *pool, GstBuffer *buffer);

  /**
   * GstBufferPoolClass::free_buffer:
   * @pool: the #GstBufferPool
   * @buffer: the #GstBuffer to free
   *
   * Free a buffer. The default implementation unrefs the buffer.
   */
  void           (*free_buffer)    (GstBufferPool *pool, GstBuffer *buffer);

  /**
   * GstBufferPoolClass::flush_start:
   * @pool: the #GstBufferPool
   *
   * Enter the flushing state.
   *
   * Since: 1.4
   */
  void           (*flush_start)    (GstBufferPool *pool);

  /**
   * GstBufferPoolClass::flush_stop:
   * @pool: the #GstBufferPool
   *
   * Leave the flushing state.
   *
   * Since: 1.4
   */
  void           (*flush_stop)     (GstBufferPool *pool);

  /*< private >*/
  gpointer _gst_reserved[GST_PADDING - 2];
};

GST_API
GType       gst_buffer_pool_get_type (void);

/* allocation */

GST_API
GstBufferPool *  gst_buffer_pool_new  (void);

/* state management */

GST_API
gboolean         gst_buffer_pool_set_active      (GstBufferPool *pool, gboolean active);

GST_API
gboolean         gst_buffer_pool_is_active       (GstBufferPool *pool);

GST_API
gboolean         gst_buffer_pool_set_config      (GstBufferPool *pool, GstStructure *config);

GST_API
GstStructure *   gst_buffer_pool_get_config      (GstBufferPool *pool);

GST_API
const gchar **   gst_buffer_pool_get_options     (GstBufferPool *pool);

GST_API
gboolean         gst_buffer_pool_has_option      (GstBufferPool *pool, const gchar *option);

GST_API
void             gst_buffer_pool_set_flushing    (GstBufferPool *pool, gboolean flushing);

/* helpers for configuring the config structure */

GST_API
void             gst_buffer_pool_config_set_params    (GstStructure *config, GstCaps *caps,
                                                       guint size, guint min_buffers, guint max_buffers);

GST_API
gboolean         gst_buffer_pool_config_get_params    (GstStructure *config, GstCaps **caps,
                                                       guint *size, guint *min_buffers, guint *max_buffers);

GST_API
void             gst_buffer_pool_config_set_allocator (GstStructure *config, GstAllocator *allocator,
                                                       const GstAllocationParams *params);

GST_API
gboolean         gst_buffer_pool_config_get_allocator (GstStructure *config, GstAllocator **allocator,
                                                       GstAllocationParams *params);

/* options */

GST_API
guint            gst_buffer_pool_config_n_options   (GstStructure *config);

GST_API
void             gst_buffer_pool_config_add_option  (GstStructure *config, const gchar *option);

GST_API
const gchar *    gst_buffer_pool_config_get_option  (GstStructure *config, guint index);

GST_API
gboolean         gst_buffer_pool_config_has_option  (GstStructure *config, const gchar *option);

GST_API
gboolean         gst_buffer_pool_config_validate_params (GstStructure *config, GstCaps *caps,
                                                         guint size, guint min_buffers, guint max_buffers);

/* buffer management */

GST_API
GstFlowReturn    gst_buffer_pool_acquire_buffer  (GstBufferPool *pool, GstBuffer **buffer,
                                                  GstBufferPoolAcquireParams *params);

GST_API
void             gst_buffer_pool_release_buffer  (GstBufferPool *pool, GstBuffer *buffer);

G_END_DECLS

#endif /* __GST_BUFFER_POOL_H__ */