Function avformat_write_header

libavformat/mux.c:467–501

}

int avformat_write_header(AVFormatContext *s, AVDictionary **options)
{
    FormatContextInternal *const fci = ff_fc_internal(s);
    int already_initialized = fci->initialized;
    int streams_already_initialized = fci->streams_initialized;
    int ret = 0;

    if (!already_initialized)
        if ((ret = avformat_init_output(s, options)) < 0)
            return ret;

    if (ffofmt(s->oformat)->write_header) {
        if (!(s->oformat->flags & AVFMT_NOFILE) && s->pb)
            avio_write_marker(s->pb, AV_NOPTS_VALUE, AVIO_DATA_MARKER_HEADER);
        ret = ffofmt(s->oformat)->write_header(s);
        if (ret >= 0 && s->pb && s->pb->error < 0)
            ret = s->pb->error;
        if (ret < 0)
            goto fail;
        flush_if_needed(s);
    }
    if (!(s->oformat->flags & AVFMT_NOFILE) && s->pb)
        avio_write_marker(s->pb, AV_NOPTS_VALUE, AVIO_DATA_MARKER_UNKNOWN);

    if (!fci->streams_initialized) {
        if ((ret = init_pts(s)) < 0)
            goto fail;
    }

    return streams_already_initialized;

fail:
    deinit_muxer(s);
    return ret;
}

#define AV_PKT_FLAG_UNCODED_FRAME 0x2000