FFmpeg/libavfilter/audio.c

/*
 * 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
 */

#include "libavutil/channel_layout.h"
#include "libavutil/common.h"

#include "audio.h"
#include "avfilter.h"
#include "internal.h"

AVFrame *ff_null_get_audio_buffer(AVFilterLink *link, int nb_samples)
{
    return ff_get_audio_buffer(link->dst->outputs[0], nb_samples);
}

AVFrame *ff_default_get_audio_buffer(AVFilterLink *link, int nb_samples)
{
    AVFrame *frame = av_frame_alloc();
    int channels = av_get_channel_layout_nb_channels(link->channel_layout);
    int ret;

    if (!frame)
        return NULL;

    frame->nb_samples     = nb_samples;
    frame->format         = link->format;
    frame->channel_layout = link->channel_layout;
    frame->sample_rate    = link->sample_rate;
    ret = av_frame_get_buffer(frame, 0);
    if (ret < 0) {
        av_frame_free(&frame);
        return NULL;
    }

    av_samples_set_silence(frame->extended_data, 0, nb_samples, channels,
                           link->format);


    return frame;
}

AVFrame *ff_get_audio_buffer(AVFilterLink *link, int nb_samples)
{
    AVFrame *ret = NULL;

    if (link->dstpad->get_audio_buffer)
        ret = link->dstpad->get_audio_buffer(link, nb_samples);

    if (!ret)
        ret = ff_default_get_audio_buffer(link, nb_samples);

    return ret;
}