/* * 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 */ #include "internal.h"#include "libavutil/mem.h"#include "libavutil/opt.h"#include "libavformat/avformat.h"#include "libavformat/demux.h" int ff_alloc_input_device_context(AVFormatContext **avctx, const AVInputFormat *iformat, const char *format){    AVFormatContext *s;    int ret = 0;     *avctx = NULL;    if (!iformat && !format)        return AVERROR(EINVAL);    if (!(s = avformat_alloc_context()))        return AVERROR(ENOMEM);     if (!iformat)        iformat = av_find_input_format(format);    if (!iformat || !iformat->priv_class || !AV_IS_INPUT_DEVICE(iformat->priv_class->category)) {        ret = AVERROR(EINVAL);        goto error;    }    s->iformat = iformat;    if (ffifmt(s->iformat)->priv_data_size > 0) {        s->priv_data = av_mallocz(ffifmt(s->iformat)->priv_data_size);        if (!s->priv_data) {            ret = AVERROR(ENOMEM);            goto error;        }        if (s->iformat->priv_class) {            *(const AVClass**)s->priv_data= s->iformat->priv_class;            av_opt_set_defaults(s->priv_data);        }    } else        s->priv_data = NULL;     *avctx = s;    return 0;  error:    avformat_free_context(s);    return ret;}