112 lines
3.1 KiB
C
112 lines
3.1 KiB
C
/*
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* Generic buffer queue
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* Copyright (c) 2012 Nicolas George
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef AVFILTER_BUFFERQUEUE_H
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#define AVFILTER_BUFFERQUEUE_H
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/**
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* FFBufQueue: simple AVFilterBufferRef queue API
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*
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* Note: this API is not thread-safe. Concurrent access to the same queue
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* must be protected by a mutex or any synchronization mechanism.
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*/
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/**
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* Maximum size of the queue.
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*
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* This value can be overridden by definying it before including this
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* header.
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* Powers of 2 are recommended.
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*/
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#ifndef FF_BUFQUEUE_SIZE
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#define FF_BUFQUEUE_SIZE 32
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#endif
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#include "avfilter.h"
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#include "libavutil/avassert.h"
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/**
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* Structure holding the queue
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*/
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struct FFBufQueue {
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AVFilterBufferRef *queue[FF_BUFQUEUE_SIZE];
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unsigned short head;
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unsigned short available; /**< number of available buffers */
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};
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#define BUCKET(i) queue->queue[(queue->head + (i)) % FF_BUFQUEUE_SIZE]
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/**
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* Add a buffer to the queue.
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*
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* If the queue is already full, then the current last buffer is dropped
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* (and unrefed) with a warning before adding the new buffer.
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*/
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static inline void ff_bufqueue_add(void *log, struct FFBufQueue *queue,
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AVFilterBufferRef *buf)
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{
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if (queue->available == FF_BUFQUEUE_SIZE) {
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av_log(log, AV_LOG_WARNING, "Buffer queue overflow, dropping.\n");
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avfilter_unref_buffer(BUCKET(--queue->available));
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}
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BUCKET(queue->available++) = buf;
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}
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/**
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* Get a buffer from the queue without altering it.
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*
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* Buffer with index 0 is the first buffer in the queue.
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* Return NULL if the queue has not enough buffers.
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*/
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static inline AVFilterBufferRef *ff_bufqueue_peek(struct FFBufQueue *queue,
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unsigned index)
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{
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return index < queue->available ? BUCKET(index) : NULL;
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}
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/**
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* Get the first buffer from the queue and remove it.
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*
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* Do not use on an empty queue.
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*/
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static inline AVFilterBufferRef *ff_bufqueue_get(struct FFBufQueue *queue)
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{
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AVFilterBufferRef *ret = queue->queue[queue->head];
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av_assert0(queue->available);
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queue->available--;
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queue->queue[queue->head] = NULL;
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queue->head = (queue->head + 1) % FF_BUFQUEUE_SIZE;
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return ret;
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}
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/**
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* Unref and remove all buffers from the queue.
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*/
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static inline void ff_bufqueue_discard_all(struct FFBufQueue *queue)
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{
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while (queue->available)
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avfilter_unref_buffer(ff_bufqueue_get(queue));
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}
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#undef BUCKET
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#endif /* AVFILTER_BUFFERQUEUE_H */
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