blob: f5e5df2d72b5b67b470c5ce1b2ae5ee1d18e4253
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 */ |
122 |