/*
*
* Copyright 1990-2007 Sun Microsystems, Inc. All Rights Reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 only, as published by the Free Software Foundation.
*
* 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 version 2 for more details (a copy is
* included at /legal/license.txt).
*
* You should have received a copy of the GNU General Public License
* version 2 along with this work; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
* Clara, CA 95054 or visit www.sun.com if you need additional
* information or have any questions.
*/
package javax.microedition.media.control;
/**
* The <code>FramePositioningControl</code> is the interface to control
* precise positioning to a video frame for <code>Players</code>.
* <p>
* Frame numbers for a bounded movie must be non-negative
* and should generally begin with 0,
* corresponding to media time 0. Each video frame of a movie
* must have a unique frame number that is one bigger than the
* previous frame.
* <p>
* There is a direct mapping between the frame number and the media
* time of a video frame; although not all <code>Players</code> can
* compute that relationship. For <code>Players</code> that can
* compute that relationship, the <code>mapFrameToTime</code> and
* <code>mapTimeToFrame</code> methods can be used.
* <p>
* When a <code>Player</code> is seeked or skipped to a new video frame,
* the media time of the <code>Player</code> will be changed to the
* media time of the corresponding video frame.
* <p>
* As much as possible, the methods in this interface should
* provide frame-level accuracy with a plus-or-minus-one-frame
* margin of error to accommodate for round-off errors.
* However, if the content has inaccurate frame positioning
* information, implementations may not be able to provide
* the necessary frame-level accuracy. For instance, some
* media content may contain wrong time-stamps or have missing
* frames. In any case, the results of each
* operation should represent the best effort. For the
* <code>seek</code> and <code>skip</code> methods, the returned
* value should indicate the actual new location or the number
* of frames skipped.
*
*/
public interface FramePositioningControl extends javax.microedition.media.Control {
/**
* Seek to a given video frame.
* The media time of the <code>Player</code> will be updated
* to reflect the new position set.
* <p>
* This method can be called on a stopped or started
* <code>Player</code>.
* If the <code>Player</code> is
* in the <i>Started</i> state, this method may cause the
* <code>Player</code> to change states. If that happens, the
* appropriate transition events will be posted by
* the <code>Player</code> when its state changes.
* <p>
* If the given frame number is less than the first or larger
* than the last frame number in the media, <code>seek</code>
* will jump to either the first or the last frame respectively.
*
* @param frameNumber the frame to seek to.
* @return the actual frame that the Player has seeked to.
*/
int seek(int frameNumber);
/**
* Skip a given number of frames from the current position.
* The media time of the <code>Player</code> will be updated to
* reflect the new position set.
* <p>
* This method can be called on a stopped or started <code>Player</code>.
* If the <code>Player</code> is in the <i>Started</i> state,
* the current position is changing. Hence,
* the frame actually skipped to will not be exact.
* <p>
* If the <code>Player</code> is
* in the <i>Started</i> state, this method may cause the
* <code>Player</code> to change states. If that happens, the
* appropriate transition events will be posted.
* <p>
* If the given <code>framesToSkip</code> will cause the position to
* extend beyond the first or last frame, <code>skip</code> will
* jump to the first or last frame respectively.
*
* @param framesToSkip the number of frames to skip from the current
* position. If framesToSkip is positive, it will seek forward
* by framesToSkip number of frames. If framesToSkip is negative,
* it will seek backward by framesToSkip number of frames.
* e.g. skip(-1) will seek backward one frame.
* @return the actual number of frames skipped.
*/
int skip(int framesToSkip);
/**
* Converts the given frame number to the corresponding media time.
* The method only performs the calculations. It does not
* position the media to the given frame.
*
* @param frameNumber the input frame number for the conversion.
* @return the converted media time in microseconds for the given frame.
* If the conversion fails, -1 is returned.
*/
long mapFrameToTime(int frameNumber);
/**
* Converts the given media time to the corresponding frame number.
* The method only performs the calculations. It does not
* position the media to the given media time.
* <p>
* The frame returned is the nearest frame that has a media time
* less than or equal to the given media time.
* <p>
* <code>mapTimeToFrame(0)</code> must not fail and must
* return the frame number of the first frame.
*
* @param mediaTime the input media time for the
* conversion in microseconds.
* @return the converted frame number for the given media time.
* If the conversion fails, -1 is returned.
*/
int mapTimeToFrame(long mediaTime);
}
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