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ffmpeg / libavfilter / vf_fifo.c @ 2912e87a

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/*
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 * Copyright (c) 2007 Bobby Bingham
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 *
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 * This file is part of Libav.
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 *
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 * Libav 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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 * Libav 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 Libav; 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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/**
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 * @file
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 * FIFO buffering video filter
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 */
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#include "avfilter.h"
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typedef struct BufPic {
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    AVFilterBufferRef *picref;
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    struct BufPic     *next;
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} BufPic;
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typedef struct {
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    BufPic  root;
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    BufPic *last;   ///< last buffered picture
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} FifoContext;
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static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
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{
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    FifoContext *fifo = ctx->priv;
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    fifo->last = &fifo->root;
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    av_log(ctx, AV_LOG_INFO, "\n");
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    return 0;
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}
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static av_cold void uninit(AVFilterContext *ctx)
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{
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    FifoContext *fifo = ctx->priv;
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    BufPic *pic, *tmp;
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    for (pic = fifo->root.next; pic; pic = tmp) {
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        tmp = pic->next;
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        avfilter_unref_buffer(pic->picref);
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        av_free(pic);
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    }
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}
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static void start_frame(AVFilterLink *inlink, AVFilterBufferRef *picref)
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{
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    FifoContext *fifo = inlink->dst->priv;
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    fifo->last->next = av_mallocz(sizeof(BufPic));
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    fifo->last = fifo->last->next;
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    fifo->last->picref = picref;
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}
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static void end_frame(AVFilterLink *inlink) { }
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static void draw_slice(AVFilterLink *inlink, int y, int h, int slice_dir) { }
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static int request_frame(AVFilterLink *outlink)
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{
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    FifoContext *fifo = outlink->src->priv;
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    BufPic *tmp;
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    int ret;
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    if (!fifo->root.next) {
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        if ((ret = avfilter_request_frame(outlink->src->inputs[0]) < 0))
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            return ret;
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    }
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    /* by doing this, we give ownership of the reference to the next filter,
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     * so we don't have to worry about dereferencing it ourselves. */
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    avfilter_start_frame(outlink, fifo->root.next->picref);
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    avfilter_draw_slice (outlink, 0, outlink->h, 1);
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    avfilter_end_frame  (outlink);
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    if (fifo->last == fifo->root.next)
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        fifo->last = &fifo->root;
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    tmp = fifo->root.next->next;
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    av_free(fifo->root.next);
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    fifo->root.next = tmp;
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    return 0;
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}
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AVFilter avfilter_vf_fifo = {
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    .name      = "fifo",
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    .description = NULL_IF_CONFIG_SMALL("Buffer input images and send them when they are requested."),
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    .init      = init,
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    .uninit    = uninit,
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    .priv_size = sizeof(FifoContext),
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    .inputs    = (AVFilterPad[]) {{ .name            = "default",
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                                    .type            = AVMEDIA_TYPE_VIDEO,
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                                    .get_video_buffer= avfilter_null_get_video_buffer,
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                                    .start_frame     = start_frame,
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                                    .draw_slice      = draw_slice,
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                                    .end_frame       = end_frame,
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                                    .rej_perms       = AV_PERM_REUSE2, },
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                                  { .name = NULL}},
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    .outputs   = (AVFilterPad[]) {{ .name            = "default",
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                                    .type            = AVMEDIA_TYPE_VIDEO,
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                                    .request_frame   = request_frame, },
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                                  { .name = NULL}},
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};