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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 | */ | |
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 | */ | |
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 | */ | |
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 | */ | |
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 | */ | |
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 */ |