PeerStreamer

/*

 * This file is part of Libav.

 *

 * Libav 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.

 *

 * Libav 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 Libav; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * null audio source

 */

#include "avfilter.h"

#include "libavutil/audioconvert.h"

typedef struct {

    int64_t channel_layout;

    int64_t sample_rate;

} ANullContext;

static int init(AVFilterContext *ctx, const char *args, void *opaque)

{

    ANullContext *priv = ctx->priv;

    char channel_layout_str[128] = "";

    priv->sample_rate = 44100;

    priv->channel_layout = AV_CH_LAYOUT_STEREO;

    if (args)

        sscanf(args, "%"PRId64":%s", &priv->sample_rate, channel_layout_str);

    if (priv->sample_rate < 0) {

        av_log(ctx, AV_LOG_ERROR, "Invalid negative sample rate: %"PRId64"\n", priv->sample_rate);

        return AVERROR(EINVAL);

    }

    if (*channel_layout_str)

        if (!(priv->channel_layout = av_get_channel_layout(channel_layout_str))

            && sscanf(channel_layout_str, "%"PRId64, &priv->channel_layout) != 1) {

            av_log(ctx, AV_LOG_ERROR, "Invalid value '%s' for channel layout\n",

                   channel_layout_str);

            return AVERROR(EINVAL);

        }

    return 0;

}

static int config_props(AVFilterLink *outlink)

{

    ANullContext *priv = outlink->src->priv;

    char buf[128];

    int chans_nb;

    outlink->sample_rate = priv->sample_rate;

    outlink->channel_layout = priv->channel_layout;

    chans_nb = av_get_channel_layout_nb_channels(priv->channel_layout);

    av_get_channel_layout_string(buf, sizeof(buf), chans_nb, priv->channel_layout);

    av_log(outlink->src, AV_LOG_INFO,

           "sample_rate:%"PRId64 " channel_layout:%"PRId64 " channel_layout_description:'%s'\n",

           priv->sample_rate, priv->channel_layout, buf);

    return 0;

}

static int request_frame(AVFilterLink *link)

{

    return -1;

}

AVFilter avfilter_asrc_anullsrc = {

    .name        = "anullsrc",

    .description = NULL_IF_CONFIG_SMALL("Null audio source, never return audio frames."),

    .init        = init,

    .priv_size   = sizeof(ANullContext),

    .inputs      = (AVFilterPad[]) {{ .name = NULL}},

    .outputs     = (AVFilterPad[]) {{ .name = "default",

                                      .type = AVMEDIA_TYPE_AUDIO,

                                      .config_props = config_props,

                                      .request_frame = request_frame, },

                                    { .name = NULL}},

};