1 files changed, 296 insertions, 0 deletions
diff --git a/libavfilter/framesync.h b/libavfilter/framesync.h
new file mode 100644
index 0000000000..2072781054
--- /dev/null
+++ b/libavfilter/framesync.h
@@ -0,0 +1,296 @@
+/*
+ * Copyright (c) 2013 Nicolas George
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVFILTER_FRAMESYNC_H
+#define AVFILTER_FRAMESYNC_H
+
+#include "bufferqueue.h"
+
+/*
+ * TODO
+ * Callback-based API similar to dualinput.
+ * Export convenient options.
+ */
+
+/**
+ * This API is intended as a helper for filters that have several video
+ * input and need to combine them somehow. If the inputs have different or
+ * variable frame rate, getting the input frames to match requires a rather
+ * complex logic and a few user-tunable options.
+ *
+ * In this API, when a set of synchronized input frames is ready to be
+ * procesed is called a frame event. Frame event can be generated in
+ * response to input frames on any or all inputs and the handling of
+ * situations where some stream extend beyond the beginning or the end of
+ * others can be configured.
+ *
+ * The basic working of this API is the following:
+ *
+ * - When a frame is available on any input, add it using
+ *   ff_framesync_add_frame().
+ *
+ * - When a frame event is ready to be processed (i.e. after adding a frame
+ *   or when requested on input):
+ *   - call ff_framesync_next();
+ *   - if fs->frame_ready is true, process the frames;
+ *   - call ff_framesync_drop().
+ */
+
+/**
+ * Stream extrapolation mode
+ *
+ * Describe how the frames of a stream are extrapolated before the first one
+ * and after EOF to keep sync with possibly longer other streams.
+ */
+enum FFFrameSyncExtMode {
+
+    /**
+     * Completely stop all streams with this one.
+     */
+    EXT_STOP,
+
+    /**
+     * Ignore this stream and continue processing the other ones.
+     */
+    EXT_NULL,
+
+    /**
+     * Extend the frame to infinity.
+     */
+    EXT_INFINITY,
+};
+
+/**
+ * Input stream structure
+ */
+typedef struct FFFrameSyncIn {
+
+    /**
+     * Queue of incoming AVFrame, and NULL to mark EOF
+     */
+    struct FFBufQueue queue;
+
+    /**
+     * Extrapolation mode for timestamps before the first frame
+     */
+    enum FFFrameSyncExtMode before;
+
+    /**
+     * Extrapolation mode for timestamps after the last frame
+     */
+    enum FFFrameSyncExtMode after;
+
+    /**
+     * Time base for the incoming frames
+     */
+    AVRational time_base;
+
+    /**
+     * Current frame, may be NULL before the first one or after EOF
+     */
+    AVFrame *frame;
+
+    /**
+     * Next frame, for internal use
+     */
+    AVFrame *frame_next;
+
+    /**
+     * PTS of the current frame
+     */
+    int64_t pts;
+
+    /**
+     * PTS of the next frame, for internal use
+     */
+    int64_t pts_next;
+
+    /**
+     * Boolean flagging the next frame, for internal use
+     */
+    uint8_t have_next;
+
+    /**
+     * State: before first, in stream or after EOF, for internal use
+     */
+    uint8_t state;
+
+    /**
+     * Synchronization level: frames on input at the highest sync level will
+     * generate output frame events.
+     *
+     * For example, if inputs #0 and #1 have sync level 2 and input #2 has
+     * sync level 1, then a frame on either input #0 or #1 will generate a
+     * frame event, but not a frame on input #2 until both inputs #0 and #1
+     * have reached EOF.
+     *
+     * If sync is 0, no frame event will be generated.
+     */
+    unsigned sync;
+
+} FFFrameSyncIn;
+
+/**
+ * Frame sync structure.
+ */
+typedef struct FFFrameSync {
+    const AVClass *class;
+    void *parent;
+
+    /**
+     * Number of input streams
+     */
+    unsigned nb_in;
+
+    /**
+     * Time base for the output events
+     */
+    AVRational time_base;
+
+    /**
+     * Timestamp of the current event
+     */
+    int64_t pts;
+
+    /**
+     * Callback called when a frame event is ready
+     */
+    int (*on_event)(struct FFFrameSync *fs);
+
+    /**
+     * Opaque pointer, not used by the API
+     */
+    void *opaque;
+
+    /**
+     * Index of the input that requires a request
+     */
+    unsigned in_request;
+
+    /**
+     * Synchronization level: only inputs with the same sync level are sync
+     * sources.
+     */
+    unsigned sync_level;
+
+    /**
+     * Flag indicating that a frame event is ready
+     */
+    uint8_t frame_ready;
+
+    /**
+     * Flag indicating that output has reached EOF.
+     */
+    uint8_t eof;
+
+    /**
+     * Array of inputs; all inputs must be in consecutive memory
+     */
+    FFFrameSyncIn in[1]; /* must be the last field */
+
+} FFFrameSync;
+
+/**
+ * Initialize a frame sync structure.
+ *
+ * The entire structure is expected to be already set to 0.
+ *
+ * @param  fs      frame sync structure to initialize
+ * @param  parent  parent object, used for logging
+ * @param  nb_in   number of inputs
+ */
+void ff_framesync_init(FFFrameSync *fs, void *parent, unsigned nb_in);
+
+/**
+ * Configure a frame sync structure.
+ *
+ * Must be called after all options are set but before all use.
+ *
+ * @return  >= 0 for success or a negative error code
+ */
+int ff_framesync_configure(FFFrameSync *fs);
+
+/**
+ * Free all memory currently allocated.
+ */
+void ff_framesync_uninit(FFFrameSync *fs);
+
+/**
+ * Add a frame to an input
+ *
+ * Typically called from the filter_frame() method.
+ *
+ * @param fs     frame sync structure
+ * @param in     index of the input
+ * @param frame  input frame, or NULL for EOF
+ */
+int ff_framesync_add_frame(FFFrameSync *fs, unsigned in, AVFrame *frame);
+
+/**
+ * Prepare the next frame event.
+ *
+ * The status of the operation can be found in fs->frame_ready and fs->eof.
+ */
+void ff_framesync_next(FFFrameSync *fs);
+
+/**
+ * Drop the current frame event.
+ */
+void ff_framesync_drop(FFFrameSync *fs);
+
+/**
+ * Get the current frame in an input.
+ *
+ * @param fs      frame sync structure
+ * @param in      index of the input
+ * @param rframe  used to return the current frame (or NULL)
+ * @param get     if not zero, the calling code needs to get ownership of
+ *                the returned frame; the current frame will either be
+ *                duplicated or removed from the framesync structure
+ */
+int ff_framesync_get_frame(FFFrameSync *fs, unsigned in, AVFrame **rframe,
+                           unsigned get);
+
+/**
+ * Process one or several frame using the on_event callback.
+ *
+ * @return  number of frames processed or negative error code
+ */
+int ff_framesync_process_frame(FFFrameSync *fs, unsigned all);
+
+
+/**
+ * Accept a frame on a filter input.
+ *
+ * This function can be the complete implementation of all filter_frame
+ * methods of a filter using framesync.
+ */
+int ff_framesync_filter_frame(FFFrameSync *fs, AVFilterLink *inlink,
+                              AVFrame *in);
+
+/**
+ * Request a frame on the filter output.
+ *
+ * This function can be the complete implementation of all filter_frame
+ * methods of a filter using framesync if it has only one output.
+ */
+int ff_framesync_request_frame(FFFrameSync *fs, AVFilterLink *outlink);
+
+#endif /* AVFILTER_FRAMESYNC_H */