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Diffstat (limited to 'libavfilter/framesync.h')
-rw-r--r-- | libavfilter/framesync.h | 296 |
1 files changed, 296 insertions, 0 deletions
diff --git a/libavfilter/framesync.h b/libavfilter/framesync.h new file mode 100644 index 0000000..2072781 --- /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 */ |