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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 AVFilterBufferRef 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 32 | |
| 41 | +#endif | |
| 42 | + | |
| 43 | +#include "avfilter.h" | |
| 44 | +#include "libavutil/avassert.h" | |
| 45 | + | |
| 46 | +/** | |
| 47 | + * Structure holding the queue | |
| 48 | + */ | |
| 49 | +struct FFBufQueue { | |
| 50 | + AVFilterBufferRef *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 | + * Add a buffer to the queue. | |
| 59 | + * | |
| 60 | + * If the queue is already full, then the current last buffer is dropped | |
| 61 | + * (and unrefed) with a warning before adding the new buffer. | |
| 62 | + */ | |
| 63 | +static inline void ff_bufqueue_add(void *log, struct FFBufQueue *queue, | |
| 64 | + AVFilterBufferRef *buf) | |
| 65 | +{ | |
| 66 | + if (queue->available == FF_BUFQUEUE_SIZE) { | |
| 67 | + av_log(log, AV_LOG_WARNING, "Buffer queue overflow, dropping.\n"); | |
| 68 | + avfilter_unref_buffer(BUCKET(--queue->available)); | |
| 69 | + } | |
| 70 | + BUCKET(queue->available++) = buf; | |
| 71 | +} | |
| 72 | + | |
| 73 | +/** | |
| 74 | + * Get a buffer from the queue without altering it. | |
| 75 | + * | |
| 76 | + * Buffer with index 0 is the first buffer in the queue. | |
| 77 | + * Return NULL if the queue has not enough buffers. | |
| 78 | + */ | |
| 79 | +static inline AVFilterBufferRef *ff_bufqueue_peek(struct FFBufQueue *queue, | |
| 80 | + unsigned index) | |
| 81 | +{ | |
| 82 | + return index < queue->available ? BUCKET(index) : NULL; | |
| 83 | +} | |
| 84 | + | |
| 85 | +/** | |
| 86 | + * Get the first buffer from the queue and remove it. | |
| 87 | + * | |
| 88 | + * Do not use on an empty queue. | |
| 89 | + */ | |
| 90 | +static inline AVFilterBufferRef *ff_bufqueue_get(struct FFBufQueue *queue) | |
| 91 | +{ | |
| 92 | + AVFilterBufferRef *ret = queue->queue[queue->head]; | |
| 93 | + av_assert0(queue->available); | |
| 94 | + queue->available--; | |
| 95 | + queue->queue[queue->head] = NULL; | |
| 96 | + queue->head = (queue->head + 1) % FF_BUFQUEUE_SIZE; | |
| 97 | + return ret; | |
| 98 | +} | |
| 99 | + | |
| 100 | +/** | |
| 101 | + * Unref and remove all buffers from the queue. | |
| 102 | + */ | |
| 103 | +static inline void ff_bufqueue_discard_all(struct FFBufQueue *queue) | |
| 104 | +{ | |
| 105 | + while (queue->available) | |
| 106 | + avfilter_unref_buffer(ff_bufqueue_get(queue)); | |
| 107 | +} | |
| 108 | + | |
| 109 | +#undef BUCKET | |
| 110 | + | |
| 111 | +#endif /* AVFILTER_BUFFERQUEUE_H */ | |