1 /*
2 * Generic buffer queue
3 * Copyright (c) 2012 Nicolas George
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #ifndef AVFILTER_BUFFERQUEUE_H
23 #define AVFILTER_BUFFERQUEUE_H
24
25 /**
26 * FFBufQueue: simple AVFrame queue API
27 *
28 * Note: this API is not thread-safe. Concurrent access to the same queue
29 * must be protected by a mutex or any synchronization mechanism.
30 */
31
32 /**
33 * Maximum size of the queue.
34 *
35 * This value can be overridden by definying it before including this
36 * header.
37 * Powers of 2 are recommended.
38 */
39 #ifndef FF_BUFQUEUE_SIZE
40 #define FF_BUFQUEUE_SIZE 64
41 #endif
42
43 #include "avfilter.h"
44 #include "libavutil/avassert.h"
45
46 /**
47 * Structure holding the queue
48 */
49 struct FFBufQueue {
50 AVFrame *queue[FF_BUFQUEUE_SIZE];
51 unsigned short head;
52 unsigned short available; /**< number of available buffers */
53 };
54
55 #define BUCKET(i) queue->queue[(queue->head + (i)) % FF_BUFQUEUE_SIZE]
56
57 /**
58 * Test if a buffer queue is full.
59 */
ff_bufqueue_is_full(struct FFBufQueue * queue)60 static inline int ff_bufqueue_is_full(struct FFBufQueue *queue)
61 {
62 return queue->available == FF_BUFQUEUE_SIZE;
63 }
64
65 /**
66 * Add a buffer to the queue.
67 *
68 * If the queue is already full, then the current last buffer is dropped
69 * (and unrefed) with a warning before adding the new buffer.
70 */
ff_bufqueue_add(void * log,struct FFBufQueue * queue,AVFrame * buf)71 static inline void ff_bufqueue_add(void *log, struct FFBufQueue *queue,
72 AVFrame *buf)
73 {
74 if (ff_bufqueue_is_full(queue)) {
75 av_log(log, AV_LOG_WARNING, "Buffer queue overflow, dropping.\n");
76 av_frame_free(&BUCKET(--queue->available));
77 }
78 BUCKET(queue->available++) = buf;
79 }
80
81 /**
82 * Get a buffer from the queue without altering it.
83 *
84 * Buffer with index 0 is the first buffer in the queue.
85 * Return NULL if the queue has not enough buffers.
86 */
ff_bufqueue_peek(struct FFBufQueue * queue,unsigned index)87 static inline AVFrame *ff_bufqueue_peek(struct FFBufQueue *queue,
88 unsigned index)
89 {
90 return index < queue->available ? BUCKET(index) : NULL;
91 }
92
93 /**
94 * Get the first buffer from the queue and remove it.
95 *
96 * Do not use on an empty queue.
97 */
ff_bufqueue_get(struct FFBufQueue * queue)98 static inline AVFrame *ff_bufqueue_get(struct FFBufQueue *queue)
99 {
100 AVFrame *ret = queue->queue[queue->head];
101 av_assert0(queue->available);
102 queue->available--;
103 queue->queue[queue->head] = NULL;
104 queue->head = (queue->head + 1) % FF_BUFQUEUE_SIZE;
105 return ret;
106 }
107
108 /**
109 * Unref and remove all buffers from the queue.
110 */
ff_bufqueue_discard_all(struct FFBufQueue * queue)111 static inline void ff_bufqueue_discard_all(struct FFBufQueue *queue)
112 {
113 while (queue->available) {
114 AVFrame *buf = ff_bufqueue_get(queue);
115 av_frame_free(&buf);
116 }
117 }
118
119 #undef BUCKET
120
121 #endif /* AVFILTER_BUFFERQUEUE_H */
122