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ffmpeg / libavfilter / asrc_anullsrc.c @ 2912e87a

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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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 * null audio source
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 */
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#include "avfilter.h"
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#include "libavutil/audioconvert.h"
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typedef struct {
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    int64_t channel_layout;
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    int64_t sample_rate;
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} ANullContext;
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static int init(AVFilterContext *ctx, const char *args, void *opaque)
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{
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    ANullContext *priv = ctx->priv;
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    char channel_layout_str[128] = "";
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    priv->sample_rate = 44100;
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    priv->channel_layout = AV_CH_LAYOUT_STEREO;
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    if (args)
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        sscanf(args, "%"PRId64":%s", &priv->sample_rate, channel_layout_str);
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    if (priv->sample_rate < 0) {
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        av_log(ctx, AV_LOG_ERROR, "Invalid negative sample rate: %"PRId64"\n", priv->sample_rate);
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        return AVERROR(EINVAL);
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    }
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    if (*channel_layout_str)
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        if (!(priv->channel_layout = av_get_channel_layout(channel_layout_str))
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            && sscanf(channel_layout_str, "%"PRId64, &priv->channel_layout) != 1) {
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            av_log(ctx, AV_LOG_ERROR, "Invalid value '%s' for channel layout\n",
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                   channel_layout_str);
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            return AVERROR(EINVAL);
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        }
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    return 0;
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}
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static int config_props(AVFilterLink *outlink)
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{
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    ANullContext *priv = outlink->src->priv;
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    char buf[128];
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    int chans_nb;
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    outlink->sample_rate = priv->sample_rate;
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    outlink->channel_layout = priv->channel_layout;
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    chans_nb = av_get_channel_layout_nb_channels(priv->channel_layout);
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    av_get_channel_layout_string(buf, sizeof(buf), chans_nb, priv->channel_layout);
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    av_log(outlink->src, AV_LOG_INFO,
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           "sample_rate:%"PRId64 " channel_layout:%"PRId64 " channel_layout_description:'%s'\n",
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           priv->sample_rate, priv->channel_layout, buf);
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    return 0;
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}
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static int request_frame(AVFilterLink *link)
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{
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    return -1;
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}
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AVFilter avfilter_asrc_anullsrc = {
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    .name        = "anullsrc",
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    .description = NULL_IF_CONFIG_SMALL("Null audio source, never return audio frames."),
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    .init        = init,
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    .priv_size   = sizeof(ANullContext),
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    .inputs      = (AVFilterPad[]) {{ .name = NULL}},
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    .outputs     = (AVFilterPad[]) {{ .name = "default",
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                                      .type = AVMEDIA_TYPE_AUDIO,
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                                      .config_props = config_props,
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                                      .request_frame = request_frame, },
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                                    { .name = NULL}},
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};