diff options
Diffstat (limited to 'libavfilter/vf_framestep.c')
-rw-r--r-- | libavfilter/vf_framestep.c | 124 |
1 files changed, 124 insertions, 0 deletions
diff --git a/libavfilter/vf_framestep.c b/libavfilter/vf_framestep.c new file mode 100644 index 0000000000..f848196417 --- /dev/null +++ b/libavfilter/vf_framestep.c @@ -0,0 +1,124 @@ +/* + * Copyright (c) 2012 Stefano Sabatini + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +/** + * @file framestep filter, inspired on libmpcodecs/vf_framestep.c by + * Daniele Fornighieri <guru AT digitalfantasy it>. + */ + +#include "avfilter.h" +#include "internal.h" +#include "video.h" + +typedef struct { + int frame_step, frame_count, frame_selected; +} FrameStepContext; + +static av_cold int init(AVFilterContext *ctx, const char *args) +{ + FrameStepContext *framestep = ctx->priv; + char *tailptr; + long int n = 1; + + if (args) { + n = strtol(args, &tailptr, 10); + if (*tailptr || n <= 0 || n >= INT_MAX) { + av_log(ctx, AV_LOG_ERROR, + "Invalid argument '%s', must be a positive integer <= INT_MAX\n", args); + return AVERROR(EINVAL); + } + } + + framestep->frame_step = n; + return 0; +} + +static int config_output_props(AVFilterLink *outlink) +{ + AVFilterContext *ctx = outlink->src; + FrameStepContext *framestep = ctx->priv; + AVFilterLink *inlink = ctx->inputs[0]; + + outlink->frame_rate = + av_div_q(inlink->frame_rate, (AVRational){framestep->frame_step, 1}); + + av_log(ctx, AV_LOG_VERBOSE, "step:%d frame_rate:%d/%d(%f) -> frame_rate:%d/%d(%f)\n", + framestep->frame_step, + inlink->frame_rate.num, inlink->frame_rate.den, av_q2d(inlink->frame_rate), + outlink->frame_rate.num, outlink->frame_rate.den, av_q2d(outlink->frame_rate)); + return 0; +} + +static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *ref) +{ + FrameStepContext *framestep = inlink->dst->priv; + + if (!(framestep->frame_count++ % framestep->frame_step)) { + framestep->frame_selected = 1; + return ff_filter_frame(inlink->dst->outputs[0], ref); + } else { + framestep->frame_selected = 0; + avfilter_unref_buffer(ref); + return 0; + } +} + +static int request_frame(AVFilterLink *outlink) +{ + FrameStepContext *framestep = outlink->src->priv; + AVFilterLink *inlink = outlink->src->inputs[0]; + int ret; + + framestep->frame_selected = 0; + do { + ret = ff_request_frame(inlink); + } while (!framestep->frame_selected && ret >= 0); + + return ret; +} + +static const AVFilterPad framestep_inputs[] = { + { + .name = "default", + .type = AVMEDIA_TYPE_VIDEO, + .get_video_buffer = ff_null_get_video_buffer, + .filter_frame = filter_frame, + }, + { NULL } +}; + +static const AVFilterPad framestep_outputs[] = { + { + .name = "default", + .type = AVMEDIA_TYPE_VIDEO, + .config_props = config_output_props, + .request_frame = request_frame, + }, + { NULL } +}; + +AVFilter avfilter_vf_framestep = { + .name = "framestep", + .description = NULL_IF_CONFIG_SMALL("Select one frame every N frames."), + .init = init, + .priv_size = sizeof(FrameStepContext), + .inputs = framestep_inputs, + .outputs = framestep_outputs, +}; |