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lavfi: add an API to synchronize multiple video inputs.

Compared to dualinput, this API can handle more than two inputs and can generate frames synchronized to any or all input streams.

Nicolas George committed 13 years ago

Commit 53319d51 parent 3cfd4df2 files · +625 −0Browse files

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1+/*
2+ * Copyright (c) 2013 Nicolas George
3+ *
4+ * This file is part of FFmpeg.
5+ *
6+ * FFmpeg is free software; you can redistribute it and/or
7+ * modify it under the terms of the GNU Lesser General Public License
8+ * as published by the Free Software Foundation; either
9+ * version 2.1 of the License, or (at your option) any later version.
10+ *
11+ * FFmpeg is distributed in the hope that it will be useful,
12+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
13+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14+ * GNU Lesser General Public License for more details.
15+ *
16+ * You should have received a copy of the GNU Lesser General Public License
17+ * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
18+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19+ */
20+
21+#ifndef AVFILTER_FRAMESYNC_H
22+#define AVFILTER_FRAMESYNC_H
23+
24+#include "bufferqueue.h"
25+
26+/*
27+ * TODO
28+ * Callback-based API similar to dualinput.
29+ * Export convenient options.
30+ */
31+
32+/**
33+ * This API is intended as a helper for filters that have several video
34+ * input and need to combine them somehow. If the inputs have different or
35+ * variable frame rate, getting the input frames to match requires a rather
36+ * complex logic and a few user-tunable options.
37+ *
38+ * In this API, when a set of synchronized input frames is ready to be
39+ * procesed is called a frame event. Frame event can be generated in
40+ * response to input frames on any or all inputs and the handling of
41+ * situations where some stream extend beyond the beginning or the end of
42+ * others can be configured.
43+ *
44+ * The basic working of this API is the following:
45+ *
46+ * - When a frame is available on any input, add it using
47+ * ff_framesync_add_frame().
48+ *
49+ * - When a frame event is ready to be processed (i.e. after adding a frame
50+ * or when requested on input):
51+ * - call ff_framesync_next();
52+ * - if fs->frame_ready is true, process the frames;
53+ * - call ff_framesync_drop().
54+ */
55+
56+/**
57+ * Stream extrapolation mode
58+ *
59+ * Describe how the frames of a stream are extrapolated before the first one
60+ * and after EOF to keep sync with possibly longer other streams.
61+ */
62+enum FFFrameSyncExtMode {
63+
64+ /**
65+ * Completely stop all streams with this one.
66+ */
67+ EXT_STOP,
68+
69+ /**
70+ * Ignore this stream and continue processing the other ones.
71+ */
72+ EXT_NULL,
73+
74+ /**
75+ * Extend the frame to infinity.
76+ */
77+ EXT_INFINITY,
78+};
79+
80+/**
81+ * Input stream structure
82+ */
83+typedef struct FFFrameSyncIn {
84+
85+ /**
86+ * Queue of incoming AVFrame, and NULL to mark EOF
87+ */
88+ struct FFBufQueue queue;
89+
90+ /**
91+ * Extrapolation mode for timestamps before the first frame
92+ */
93+ enum FFFrameSyncExtMode before;
94+
95+ /**
96+ * Extrapolation mode for timestamps after the last frame
97+ */
98+ enum FFFrameSyncExtMode after;
99+
100+ /**
101+ * Time base for the incoming frames
102+ */
103+ AVRational time_base;
104+
105+ /**
106+ * Current frame, may be NULL before the first one or after EOF
107+ */
108+ AVFrame *frame;
109+
110+ /**
111+ * Next frame, for internal use
112+ */
113+ AVFrame *frame_next;
114+
115+ /**
116+ * PTS of the current frame
117+ */
118+ int64_t pts;
119+
120+ /**
121+ * PTS of the next frame, for internal use
122+ */
123+ int64_t pts_next;
124+
125+ /**
126+ * Boolean flagging the next frame, for internal use
127+ */
128+ uint8_t have_next;
129+
130+ /**
131+ * State: before first, in stream or after EOF, for internal use
132+ */
133+ uint8_t state;
134+
135+ /**
136+ * Synchronization level: frames on input at the highest sync level will
137+ * generate output frame events.
138+ *
139+ * For example, if inputs #0 and #1 have sync level 2 and input #2 has
140+ * sync level 1, then a frame on either input #0 or #1 will generate a
141+ * frame event, but not a frame on input #2 until both inputs #0 and #1
142+ * have reached EOF.
143+ *
144+ * If sync is 0, no frame event will be generated.
145+ */
146+ unsigned sync;
147+
148+} FFFrameSyncIn;
149+
150+/**
151+ * Frame sync structure.
152+ */
153+typedef struct FFFrameSync {
154+ const AVClass *class;
155+ void *parent;
156+
157+ /**
158+ * Number of input streams
159+ */
160+ unsigned nb_in;
161+
162+ /**
163+ * Time base for the output events
164+ */
165+ AVRational time_base;
166+
167+ /**
168+ * Timestamp of the current event
169+ */
170+ int64_t pts;
171+
172+ /**
173+ * Callback called when a frame event is ready
174+ */
175+ int (*on_event)(struct FFFrameSync *fs);
176+
177+ /**
178+ * Opaque pointer, not used by the API
179+ */
180+ void *opaque;
181+
182+ /**
183+ * Index of the input that requires a request
184+ */
185+ unsigned in_request;
186+
187+ /**
188+ * Synchronization level: only inputs with the same sync level are sync
189+ * sources.
190+ */
191+ unsigned sync_level;
192+
193+ /**
194+ * Flag indicating that a frame event is ready
195+ */
196+ uint8_t frame_ready;
197+
198+ /**
199+ * Flag indicating that output has reached EOF.
200+ */
201+ uint8_t eof;
202+
203+ /**
204+ * Array of inputs; all inputs must be in consecutive memory
205+ */
206+ FFFrameSyncIn in[1]; /* must be the last field */
207+
208+} FFFrameSync;
209+
210+/**
211+ * Initialize a frame sync structure.
212+ *
213+ * The entire structure is expected to be already set to 0.
214+ *
215+ * @param fs frame sync structure to initialize
216+ * @param parent parent object, used for logging
217+ * @param nb_in number of inputs
218+ */
219+void ff_framesync_init(FFFrameSync *fs, void *parent, unsigned nb_in);
220+
221+/**
222+ * Configure a frame sync structure.
223+ *
224+ * Must be called after all options are set but before all use.
225+ *
226+ * @return >= 0 for success or a negative error code
227+ */
228+int ff_framesync_configure(FFFrameSync *fs);
229+
230+/**
231+ * Free all memory currently allocated.
232+ */
233+void ff_framesync_uninit(FFFrameSync *fs);
234+
235+/**
236+ * Add a frame to an input
237+ *
238+ * Typically called from the filter_frame() method.
239+ *
240+ * @param fs frame sync structure
241+ * @param in index of the input
242+ * @param frame input frame, or NULL for EOF
243+ */
244+int ff_framesync_add_frame(FFFrameSync *fs, unsigned in, AVFrame *frame);
245+
246+/**
247+ * Prepare the next frame event.
248+ *
249+ * The status of the operation can be found in fs->frame_ready and fs->eof.
250+ */
251+void ff_framesync_next(FFFrameSync *fs);
252+
253+/**
254+ * Drop the current frame event.
255+ */
256+void ff_framesync_drop(FFFrameSync *fs);
257+
258+/**
259+ * Get the current frame in an input.
260+ *
261+ * @param fs frame sync structure
262+ * @param in index of the input
263+ * @param rframe used to return the current frame (or NULL)
264+ * @param get if not zero, the calling code needs to get ownership of
265+ * the returned frame; the current frame will either be
266+ * duplicated or removed from the framesync structure
267+ */
268+int ff_framesync_get_frame(FFFrameSync *fs, unsigned in, AVFrame **rframe,
269+ unsigned get);
270+
271+/**
272+ * Process one or several frame using the on_event callback.
273+ *
274+ * @return number of frames processed or negative error code
275+ */
276+int ff_framesync_process_frame(FFFrameSync *fs, unsigned all);
277+
278+
279+/**
280+ * Accept a frame on a filter input.
281+ *
282+ * This function can be the complete implementation of all filter_frame
283+ * methods of a filter using framesync.
284+ */
285+int ff_framesync_filter_frame(FFFrameSync *fs, AVFilterLink *inlink,
286+ AVFrame *in);
287+
288+/**
289+ * Request a frame on the filter output.
290+ *
291+ * This function can be the complete implementation of all filter_frame
292+ * methods of a filter using framesync if it has only one output.
293+ */
294+int ff_framesync_request_frame(FFFrameSync *fs, AVFilterLink *outlink);
295+
296+#endif /* AVFILTER_FRAMESYNC_H */

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